Patent Publication Number: US-7583928-B2

Title: Information providing method

Description:
TECHNICAL FIELD 
   The present invention relates to an information provision method which appropriately provides a client terminal from a specified server via a network with information associated with broadcasting of programs, for example. 
   BACKGROUND ART 
   Conventionally, radio receivers are used for audio stereo reproduction systems such as all-in-one stereo systems and separate stereo components, portable audio systems, car-mounted audio systems, and the like. The radio receiver receives and demodulates broadcast signals broadcast from a radio station and allows users to listen to programs and musical compositions. 
   On the other hand, the radio station publicizes various information about its programs on the Internet homepage. For example, the radio station broadcasts a program, and provides musical composition information as associated information about broadcast musical compositions such as their titles and artist names as well as names and numbers of CDs that record the musical compositions, to the audience in the program. 
   There is proposed an audio reproduction apparatus (e.g., see Patent Document 1: Jpn. Pat. Appln. No. 2003-274302) as a client terminal having the radio reception function and the Internet connection function implemented in one system that simultaneously performs listening of radio programs and acquisition of musical composition information. 
   This audio reproduction apparatus allows a user to listen to a program from the audio reproduction apparatus and acquire musical composition information from associated information provision servers. The musical composition information includes titles, artist names, and the like of musical compositions that are broadcast in the program. 
   With reference to  FIG. 20 , the following describes a musical composition information provision sequence. In this sequence, a client terminal CT receives a musical composition broadcasted from a radio station RS for listening. In response to an acquisition request from the client terminal CT, an associated information provision server KS provides musical composition information such as titles and artist names associated with the musical composition. 
   At step SP 1 , the radio station RS starts broadcasting musical composition A in a program. The radio station RS then proceeds to the next step SP 2  to notify the associated information provision server KS that musical composition A has started to be broadcast. The radio station RS proceeds to the next step SP 3 . 
   At step SP 11 , the associated information provision server KS maintains a database of musical composition information about titles and artist names concerning a plurality of types of musical compositions, names and numbers of CDs that record the corresponding musical compositions, and the like. It is necessary to provide the client terminal CT with musical composition information associated with musical composition A notified from the radio station RS. Specifically, the musical composition information including the title and artist names, the name and the number of the CD that records musical composition A. For this purpose, the associated information provision server KS updates the previous musical composition information to new musical composition information, and then proceeds to the next step SP 12 . 
   At step SP 21 , the client terminal CT receives musical composition A broadcasted by the radio station RS at step SP 1  so that the user can listen to it. At step SP 22 , the client terminal CT performs polling by sending an acquisition request for the musical composition information such as titles and artist names to the associated information provision server KS at an interval of 30 seconds. The client terminal CT then proceeds to the next step SP 23 . 
   The associated information provision server KS maintains the musical composition information to be provided in advance. At step SP 12 , in response to the acquisition request from the client terminal CT, the associated information provision server KS provides the client terminal CT with that musical composition information about musical composition A via the Internet  2 . The associated information provision server KS then proceeds to the next step SP 13 . 
   At step SP 23 , the client terminal CT uses a liquid crystal display or the like to display the musical composition information provided from the associated information provision server KS. Doing this allows the user to recognize the musical composition information such as the title and artist names about the musical composition A broadcasted in the program. The client terminal CT then proceeds to the next step SP 24 . 
   At step SP 3 , the radio station RS stops broadcasting musical composition A. At step SP 4 , the radio station RS terminates the current program that broadcast musical composition A, starts broadcasting the next program, and then proceeds to the next step SP 5 . 
   At step SP 24 , after a time lapse of 30 seconds from the previous acquisition request, the client terminal CT re-issues an acquisition request for musical composition information to the associated information provision server KS. 
   At step SP 13 , the associated information provision server KS provides the client terminal CT with the musical composition information as is about musical composition A broadcasted in the previous program though the radio station RS already started broadcasting the next program. The reason is that, though the program to broadcast musical composition A has terminated, the musical composition information for musical composition A is not updated and remains scheduled to be provided. 
   At step SP 25 , the client terminal CT receives the next program from the radio station RS for listening. Nevertheless, the client terminal CT acquires and displays the musical composition information about musical composition A broadcasted in the previous program, and then proceeds to the next step SP 26 . 
   Thereafter, at step SP 5 , the radio station RS starts broadcasting musical composition B in the next program. At the following step SP 6 , the radio station RS notifies the associated information provision server KS that musical composition B has started to be broadcast. 
   At step SP 14 , the associated information provision server KS reads the musical composition information about musical composition B from the database. The musical composition information about musical composition A is currently scheduled to be provided. The associated information provision server KS updates the musical composition information about musical composition A to that about musical composition B. The associated information provision server KS then proceeds to the next step SP 15 . 
   At step SP 26 , the client terminal CT follows the polling interval to re-issue an acquisition request for the musical composition information to the associated information provision server KS. The client terminal CT then proceeds to the next step SP 27 . 
   At step SP 15 , the associated information provision server KS responds to the acquisition request from the client terminal CT and provides the client terminal CT with the updated musical composition information about musical composition B. At step SP 27 , the client terminal CT acquires and displays the musical composition information about musical composition B. 
   As mentioned above, the radio station RS changes broadcast of the current program to the next as a lapse of time according to the conventional musical composition information provision sequence. In this case, the associated information provision server KS is provided with no notification from the radio station RS until the broadcast of musical composition A changes to that of musical composition B. The associated information provision server KS still keeps the musical composition information about musical composition A as the information to be provided next and does not update it. Consequently, the associated information provision server KS provides the musical composition information about the musical composition A in response to an acquisition request from the client terminal CT though the information is irrelevant to the currently on-air next program. 
   For this reason, the client terminal CT is subject to inconsistency between the next on-air program from the radio station RS and the musical composition information supplied from the associated information provision server KS. This causes inconvenience to users. 
   DISCLOSURE OF THE INVENTION 
   The present invention has been made in consideration of the foregoing. It is therefore an object of the present invention to provide an information provision method capable of ensuring consistency between a program broadcasted from a radio station and associated information supplied from an associated information provision server to realtime link the program with the associated information. 
   To solve the above-mentioned problems, an information provision method according to the present invention comprises the steps of: sequentially storing associated information concerning an on-air program in storage means and accepting an acquisition request for the associated information from a broadcast receiver to receive a broadcast signal for the program; reading the associated information stored in the storage means in accordance with timing of accepting the acquisition request and transmitting the associated information to the broadcast receiver; and when the on-air program changes to a next program, updating the associated information which should be read from the storage means for transmission. 
   The method makes it possible to update the associated information to be transmitted in synchronization with program changeover. Consequently, it is possible to provide the program in synchronization with the associated information without a time difference between both to ensure consistency. 
   An information provision apparatus according to the present invention comprises: a storage means for sequentially storing associated information concerning an on-air program; an acquisition request acceptance means for accepting an acquisition request for the associated information from a broadcast receiver to receive a broadcast signal for the program; an associated information transmission means for reading the associated information stored in the storage means synchronously with timing to accept the acquisition request by the acquisition request acceptance means and transmitting the associated information to the broadcast receiver; and an update means for, when the on-air program changes to a next program, updating the associated information which should be read from the storage means for transmission. 
   The apparatus makes it possible to update the associated information to be transmitted in synchronization with program changeover. Consequently, it is possible to provide the program in synchronization with the associated information without a time difference between both to ensure consistency. 
   An information provision program according to the present invention allows an information processing apparatus to perform the steps of: sequentially storing associated information concerning an on-air program in the storage means; accepting an acquisition request for the associated information from a broadcast receiver to receive a broadcast signal for the program; reading the associated information stored in the storage means synchronously with timing to accept the acquisition request and transmitting the associated information to the broadcast receiver; and when the on-air program changes to a next program, updating the associated information which should be read from the storage means for transmission. 
   The information provision program makes it possible to update the associated information to be transmitted in synchronization with program changeover. Consequently, it is possible to provide the program in synchronization with the associated information without a time difference between both to ensure consistency. 
   The present invention makes it possible to update the associated information to be transmitted in synchronization with program changeover, and therefore provide the program in synchronization with the associated information without a time difference between both to ensure consistency. Consequently, it is possible to realize an information provision method, an information provision apparatus, and an information provision program capable of ensuring consistency between a program broadcasted from a radio station and associated information supplied from an associated information provision server to realtime link the program with the associated information. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic diagram showing the overall configuration of an information provision system according to a first embodiment of the present invention; 
       FIG. 2  is a schematic block diagram showing the configuration of a radio station; 
       FIG. 3  is a schematic block diagram showing the configuration of a URL provision server; 
       FIG. 4  is a schematic block diagram showing the configuration of an associated information provision server; 
       FIG. 5  is a schematic block diagram showing the circuit configuration of a client terminal; 
       FIG. 6  is a schematic diagram illustrating directory management of contents; 
       FIG. 7  is a schematic diagram showing program modules of the client terminal; 
       FIG. 8  is a schematic diagram showing a state information provision sequence not to determine whether or not a URL is available; 
       FIG. 9  is a schematic diagram showing a state information screen; 
       FIG. 10  is a schematic diagram showing a state information provision sequence to determine whether or not a URL is available; 
       FIG. 11  is a schematic diagram showing a musical composition information provision sequence according to the present invention; 
       FIG. 12  is a schematic diagram showing a program information provision sequence according to the present invention; 
       FIG. 13  is a block diagram showing the hardware configuration using functional circuit blocks of the client terminal according to a second embodiment of the present invention; 
       FIG. 14  is a block diagram showing the hardware configuration using functional circuit blocks of a portal server; 
       FIG. 15  is a block diagram showing the hardware configuration using functional circuit blocks of radio broadcast information delivery server; 
       FIG. 16  is a sequence chart showing a user authentication process between the client terminal and the portal server; 
       FIG. 17  is a sequence chart showing a user authentication process between the client terminal and a service provision server; 
       FIG. 18  is a sequence chart showing a radio broadcast information (on-air-list information) delivery service provision process; 
       FIG. 19  is a sequence chart showing a radio broadcast information (now-on-air information) delivery service provision process; and 
       FIG. 20  is a schematic block diagram showing a conventional musical composition information provision sequence. 
   

   BEST MODE FOR CARRYING OUT THE INVENTION 
   Embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
   (1) FIRST EMBODIMENT 
   (1-1) Overall Configuration of the Information Provision System 
   As shown in  FIG. 1 , the reference numeral  1  denotes an information provision system constituting the present invention as a whole. A client terminal CT receives broadcast from a radio station RS. 
   In the information provision system  1 , the radio station RS connects with an associated information provision server KS comprising a computer. A leased line is used for this connection. In place of the radio station RS, the associated information provision server KS provides a homepage of the radio station RS. In response to an acquisition request from the client terminal CT, the associated information provision server KS can provide musical composition information as associated information about musical compositions broadcast from the radio station RS via a network  2  such as the Internet. 
   In the information provision system  1 , a URL provision server  3  comprising a computer is notified of URL (Uniform Resource Locator) information that indicates an access destination of the information provision service provided by the associated information provision server KS using the homepage and the like. 
   If a change is made in the URL indicating the access destination of the information provision service, the URL provision server  3  manages the changed URL according to notification from the associated information provision server KS. The URL provision server  3  can always provide the most recent URL in response to an inquiry from the client terminal CT about the access destination of the information provision service provided by the radio station RS. 
   Since the radio broadcast is limited to receivable areas, the same frequency may be commonly shared among a plurality of areas. For example, the 80.0 MHz frequency is used by FM Tokyo in the Tokyo metropolitan area and by FM Aomori in the Tohoku district. 
   Accordingly, the client terminal CT cannot specify the radio station RS only by specifying the frequency for the URL provision server  3 . The client terminal CT further notifies the URL provision server  3  of specific information called a call sign to specify the radio station RS. In this manner, the client terminal CT can reliably receive the URL from the URL provision server  3 . As mentioned above, the URL indicates the access destination of the information provision service provided by the radio station RS. 
   (1-2) Configuration of the Radio Station RS 
   As shown in  FIG. 2 , the radio station RS includes a control section  70  comprising a CPU (Central Processing Unit). The control section  70  uses a ROM (Read only Memory)  71  and RAM (Random Access Memory)  72  to start basic programs such as an OS (Operating System) and various application programs. Based on these programs, the control section  70  controls the entire system in a unified fashion. The radio station RS performs processes such as program broadcasting to broadcast programs from a broadcast transmission section  73  to the client terminal CT via an antenna  74 . 
   The radio station RS uses a content database  74  to store many contents such as previously recorded programs and musical compositions to be broadcast in the programs. The radio station RS broadcasts the program according to a program schedule and broadcasts musical composition contents in the program as needed. 
   In this case, the radio station RS uses a data communication processing section  76  to notify the associated information provision server KS that musical compositions are broadcast in the program. In addition, the radio station RS notifies the associated information provision server KS which program is currently being broadcast. 
   (1-3) Configuration of the URL Provision Server 
   As shown in  FIG. 3 , the URL provision server  3  includes a control section  80  comprising a CPU. The control section  80  uses ROM  81  and RAM  82  to start basic programs such as an OS and various application programs. Based on these programs, the URL provision server  3  performs overall control, specified operations, and the like. 
   The URL provision server  3  receives a call sign from the client terminal CT, then the server  3  searches a URL storage database  83  for a URL of the homepage provided as an information provision service by the radio station RS corresponding to the call sign. The URL provision server  3  returns the URL to the client terminal CT via a data communication processing section  84 . 
   The URL provision server  3  is also connected to the associated information provision server KS ( FIG. 1 ). The URL provision server  3  receives state information representing service states in the associated information provision server KS via the data communication processing section  84 . The URL provision server  3  provides the client terminal CT with the state information as well as the URL. 
   (1-4) Configuration of the Associated Information Provision Server 
   As shown in  FIG. 4 , the associated information provision server KS includes a control section  90  comprising a CPU. The control section  90  uses a ROM  91  and RAM  92  to start basic programs such as an OS and various application programs. Based on these programs, the associated information provision server KS performs overall control, specified operations, and the like. 
   The associated information provision server KS searches a musical composition information database  93  for musical composition information about musical compositions broadcast in a program by the radio station RS, for example. The associated information provision server KS provides the musical composition information as associated information to the client terminal CT via the data communication processing section  95 . 
   Further, the associated information provision server KS searches a program information database  94  for program information about performers, a DJ name, genres, and the like associated with a program broadcast by the radio station RS. The associated information provision server KS provides the program information as associated information to the client terminal CT via the data communication processing section  95 . 
   (1-5) Circuit Configuration of the Client Terminal CT 
   As shown in  FIG. 5 , a CPU  11  of the client terminal CT reads basic programs such as an OS and various application programs from a ROM  13  connected via a bus  12  and expands the programs in a RAM  20 . Based on these programs, the CPU  11  performs overall control, specified operations, and the like. For example, the CPU  11  performs communication operations via the network  2 , input/output operations in relation to users, reproduction of contents from media, writing of contents downloaded from the radio station RS onto a hard disk drive (HDD)  21 , management of contents, and the like. 
   The operation input section  15  sends input information to an input processing section  14 . The input information corresponds to user operations for various operation devices provided on the surface of the main unit cabinet or a remote controller (not shown). The input processing section  14  applies specified processes to the input information and sends it as an operation command to the CPU  11 . The CPU  11  performs processes corresponding to the operation command. 
   A display  17  represents a display device such as a liquid crystal display and may be directly attached to the surface of the main unit cabinet or may be externally connected. The display  17  displays processing results from the CPU  11  and the other various information. 
   A media drive  19  reproduces, for example, a CD (Compact Disc) or Memory Stick (registered trademark) comprising flash memory and the like. An audio data processing section  24  digital-to-analog converts the reproduction result which is then output from a 2-channel speaker  25 . 
   When the CPU  11  reproduces data, e.g., a musical composition&#39;s audio content via the media drive  19 , the audio content can be stored as an audio data file in a hard disk drive  21 . 
   Further, the CPU  11  uses the media drive  19  to read a plurality of still pictures stored in Memory Stick. These still pictures can be displayed as a slideshow on the display  17  via a display processing section  16 . 
   In addition, the CPU  11  can randomly access and read a plurality of musical compositions stored in the hard disk drive  21  to reproduce the musical compositions in a user-specified order like a jukebox. 
   A tuner section  27  is equivalent to an AM or FM radio tuner, for example. The tuner section  27  demodulates a broadcast signal received at an antenna  26  under the control of the CPU  11 . The result, as a broadcast audio, is passed to the audio data processing section  24  and is output from the speaker  25 . 
   A communication processing section  22  encodes transmission data under the control of the CPU  11 . The communication processing section  22  uses a network interface  23  to transmit data to external network-compliant devices via a network  2 . The communication processing section  22  uses the network interface  23  to receive data from external network-compliant devices and decodes the received data. The communication processing section  22  then transfers the decoded data to the CPU  11 . 
   (1-6) Directory Management of Contents 
   The CPU  11  of the client terminal CT manages contents to be stored in the hard disk drive  21  according to directory structure as shown in  FIG. 6 . There are created any number of “folder” directories within a specified range under a “root” directory. The “folder” directory is created in accordance with a genre of contents, an owner user, and the like. 
   Under the “folder” directory, there are created any number of “album” directories within a specified range. The “album” directory corresponds to one album title, for example. The “album” directory stores one or more “track” files belonging to the “album” directory. That is to say, the “track” file is equivalent to one musical composition, i.e., a content. 
   A database file is stored in the hard disk drive  21  and is used for the directory management of contents. 
   (1-7) Program Module Configuration of the Client Terminal CT 
   As shown in  FIG. 7 , the client terminal CT comprises program modules operating under the OS. Specifically, the client terminal CT interacts with various servers such as a CD seller server  31  to sell CDs, an Internet radio server  32 , a music delivery operation server  33 , an overall service server  34 , and the associated information provision server KS. 
   An HTTP (Hyper Text Transfer Protocol) message program  36  uses HTTP communication to interact with various servers such as the CD seller server  31 , the Internet radio server  32 , the music delivery operation server  33 , the overall service server  34  to provide overall services, and the associated information provision server KS. A communicator program  37  is a program module to exchange data with the HTTP message program  36 . 
   Above the communicator program  37 , there are a content reproduction module  38  and a copyright protection information management module  39 . The content reproduction module  38  interprets codec information of contents and reproduces the contents. The copyright protection information management module  39  handles information about copyright protection. The content reproduction module  38  and the copyright protection information management module  39  correspond to an Internet radio channel selection/reproduction module  43  and a musical composition purchase/reproduction module  44 , respectively. The Internet radio channel selection/reproduction module  43  selects and reproduces Internet radio channels. The musical composition purchase/reproduction module  44  controls purchase of musical compositions and reproduces samples. 
   An XML (extensible Markup Language) browser  50  is positioned above the Internet radio channel selection/reproduction module  43  and the musical composition purchase/reproduction module  44 . The XML browser  50  interprets XML files from various servers and displays them on the display  17 . 
   For example, a user selects a musical composition using the XML browser  50 . The selected musical-composition is purchased through the musical composition purchase/reproduction module  44  and is written to the hard disk drive  21  via a hard disk contents controller  42 . 
   The communicator program  37  connects with an authentication library  47 A of a library  47 . The authentication library  47 A authenticates various servers such as the overall service server  34 . 
   Above the communicator program  37 , there are a database access module  40 , a content data access module  41 , and a hard disk contents controller  42 . 
   The database access module  40  accesses various databases configured in the hard disk drive  21 . The content data access module  41  accesses contents stored in the hard disk drive  21 . The hard disk contents controller  42  manages contents stored in the hard disk drive  21 . 
   Above the hard disk contents controller  42 , there are an associated information display module  45  and a tuner selection/reproduction/recording module  46 . The associated information display module  45  displays titles and artist names of musical compositions broadcast by the radio station RS. The tuner selection/reproduction/recording module  46  selects a radio station RS and records musical composition contents received from the radio station RS on the hard disk drive  21 . 
   When a musical composition is received from the radio station RS selected via an audio user interface  51 , for example, the received musical composition is written to the hard disk drive  21  via the content data access module  41 . 
   The associated information display module  45  receives associated information from the associated information provision server KS via the HTTP message program  36 . The associated information includes titles and artist names of the musical compositions currently broadcast by the radio station RS corresponding to the tuner selection/reproduction/recording module  46 . The associated information is displayed on the display  17  via the audio user interface (UI)  51 . 
   The associated information can be not only displayed on the display  17  via the audio user interface  51 , but also temporarily stored in a clip library  47 B of the library  47 . According to a user instruction, the associated information is finally stored in the hard disk drive  21  via the database access module  40 . 
   The other program modules for the client terminal CT include a CD reproduction module  48  and an HDD reproduction module  49 . The CD reproduction module  48  reproduces CDs. The HDD reproduction module  49  reproduces the hard disk drive  21 . A reproduction result is output via the audio data processing section  24  and the speaker  25 . 
   (1-8) State Information Provision Sequence of the Information Provision Service 
   The radio station RS provides a homepage as one of information provision services. The URL provision server  3  provides the client terminal CT with the homepage&#39;s most recent and accurate URL via the network  2 . At the same time, the client terminal CT is provided with states of the information provision service. A state information provision process is used for this purpose. The following describes the state information provision process. 
   (1-8-1) State Information Provision Sequence Not to Determine Availability of URL 
   At step SP 31  as shown in  FIG. 8 , the associated information provision server KS provides a homepage of the radio station RS via the network  2 . The homepage may be serviced, may stop providing services, or may be subject to maintenance. In such cases, the associated information provision server KS passes these service states as state information to the URL provision server  3 . 
   The associated information provision server KS can also pass the other state information such as information about the associated information provision server KS, a homepage URL of the radio station RS, and additional messages. 
   At step SP 41 , the URL provision server  3  identifies the state information provided from the associated information provision server KS, i.e., the information about the associated information provision server KS, the radio station RS&#39;s homepage URL, the homepage&#39;s service state, and additional messages. The URL provision server  3  stores the state information in the URL storage database  83  ( FIG. 3 ) and then proceeds to the next step SP 42 . 
   At step SP 51 , the client terminal CT issues a URL acquisition request to the URL provision server  3  so as to access the radio station RS&#39;s homepage by sending a call sign to specify the radio station RS and user information (user ID, password, authentication session ID, and the like) to the URL provision server  3 . The client terminal CT then proceeds to the next step SP 52 . 
   At step SP 42 , the URL provision server  3  specifies the radio station RS based on the call sign from the client terminal CT. The URL provision server  3  reads the state information corresponding to the specified radio station RS from the URL storage database  83 . The URL provision server  3  provides the state information to the client terminal CT via the network  2 . At this time, the URL provision server  3  authenticates the user information sent from the client terminal CT. This will be described in more detail with reference to a second embodiment later. 
   At step SP 52 , the client terminal CT acquires the state information from the URL provision server  3  and displays it on the display  17  to notify the user of the information provision service state. Further, the client terminal CT temporarily stores a state information provision URL of the state information in the RAM  20  and the HDD  21  with reference to the call sign. The client terminal CT then proceeds to the next step SP 53 . 
   As shown in  FIG. 9 , for example, the client terminal CT displays a state information screen  100  on the display  17  to notify the user of information provision service states. More specifically, a URL display area  101  shows a URL to indicate the access destination of the radio station RS&#39;s homepage. A state information display area  102  shows availability of the information provision service using a message such as “The information provision service is now available from the homepage”. An additional message display area  103  shows an additional message such as “The service will stop from 2:00 to 5:00 am on month day Ä because of the scheduled maintenance”. 
   At step SP 53 , the client terminal CT determines whether or not the information provision service is performed based on the state information contents. Only if it is determined that the information provision service is performed, the client terminal CT proceeds to the next step SP 54 . When the state information contains a state information provision URL, for example, the client terminal CT determines that the information provision service is performed. 
   If it is determined at step SP 54  that the information provision service is performed, the client terminal CT accesses the temporarily stored state information provision URL, i.e., the homepage of the information provision service. The client terminal CT issues a request to the associated information provision server KS to acquire the associated information about programs and musical compositions broadcast from the radio station RS. 
   At step SP 32 , the associated information provision server KS provides the associated information about programs and musical compositions in response to the acquisition request from the client terminal CT via the network  2 . At this time, the associated information provision server KS performs authentication based on the user information sent from the client terminal CT. This will be described in more detail with reference to the second embodiment later. 
   (1-8-2) State Information Acquisition Sequence to Determine Availability of URL 
   At step SP 61  as shown in  FIG. 10  the associated information provision server KS functions like step SP 31 . The homepage may be serviced, may stop providing services, or may be subject to maintenance. In such cases, the associated information provision server KS passes these service states as the state information to the URL provision server  3 . 
   The associated information provision server KS can also pass the other state information such as information about the associated information provision server KS, a homepage URL of the radio station RS, and additional messages. 
   At step SP 71 , the URL provision server  3  identifies the state information provided from the associated information provision server KS, i.e., information provision service states such as the information about the associated information provision server KS, the radio station RS&#39;s homepage URL, the homepage&#39;s service state, and additional messages. The URL provision server  3  stores the state information in the URL storage database  83  ( FIG. 3 ) and then proceeds to the next step SP 72 . 
   At step SP 81 , the client terminal CT issues a URL acquisition request to the URL provision server  3  so as to access the radio station RS&#39;s homepage by sending a call sign to specify the radio station RS and user information (user ID, password, authentication session ID, and the like) to the URL provision server  3 . The client terminal CT then proceeds to the next step SP 82 . 
   At step SP 72 , the URL provision server  3  specifies the radio station RS based on the call sign from the client terminal CT. The URL provision server  3  reads the state information corresponding to the specified radio station RS from the URL storage database  83 . The URL provision server  3  determines whether or not the state information contains the URL of the homepage provided by the radio station RS. If the result is negative, the URL provision server  3  proceeds to the next step SP 73 . At this time, the URL provision server  3  authenticates the user information sent from the client terminal CT. This will be described in more detail with reference to the second embodiment later. 
   At step SP 73 , it is determined that no URL-is contained in the state information. This indicates that the information provision service is currently unavailable and that no homepage exists. At this time, the URL provision server  3  adds to the state information a message indicating unavailability of the information provision service such as “The homepage presently provides no information provision service”. The URL provision server  3  provides this state information to the client terminal CT. 
   If the result is affirmative at step SP 72 , however, the URL provision server  3  proceeds to the next step SP 74 . The URL provision server  3  provides the client terminal CT with the state information read from the URL storage database  83  via the network  2 , and then proceeds to the next step SP 75 . 
   At step SP 82 , the client terminal CT acquires the state information from the URL provision server  3  and displays it on the display  17  to notify the user of the information provision service state. Further, the client terminal CT temporarily stores a state information provision URL of the state information in the RAM  20  and the HDD  21  with reference to the call sign. The client terminal CT then proceeds to the next step SP 83 . 
   Let us assume that there is provided the state information including the message indicating unavailability of the information provision service at step SP 73 .. The client terminal CT displays the message such as “The homepage presently provides no information provision service” on the display  17 . 
   On the other hand, let us assume that there is provided the state information including the URL at step SP 74 . The client terminal CT can display the state information screen  100  ( FIG. 9 ) on the display  17  to visually notify the user of information provision service states in advance. More specifically, the state information screen  100  displays the URL to indicate the access destination of the radio station RS&#39;s homepage, availability of the information provision service from the homepage, and the additional message such as “The service will stop from 2:00 to 5:00 am on month, day Ä because of the scheduled maintenance”. 
   At step SP 83 , the client terminal CT determines whether or not the information provision service is performed based on the state information contents. Only if it is determined that the information provision service is performed, the client terminal CT proceeds to the next step SP 84 . 
   If it is determined at step SP 84  that the information provision service is performed, the client terminal CT accesses the temporarily stored state information provision URL, i.e., the homepage of the information provision service. The client terminal CT issues a request to the associated information provision server KS to acquire the associated information about programs and musical compositions broadcast from the radio station RS. 
   At step SP 62 , the associated information provision server KS provides the associated information about programs and musical compositions in response to the acquisition request from the client terminal CT via the network  2 . At this time, the associated information provision server KS performs authentication based on the user information sent from the client terminal CT. This will be described in more detail with reference to the second embodiment later. 
   (1-9) Associated Information Provision Sequences 
   (1-9-1) Musical Composition Information Provision Sequence 
   Referring now to  FIG. 11 , the following describes a process in which the associated information provision server KS follows a specified information provision program and uses the homepage to provide the client terminal CT with the associated information comprising musical composition information about musical compositions broadcast by the radio station RS. 
   At step SP 101 , the radio station RS starts broadcasting musical composition A in the current program, and then proceeds to the next step SP 102 . 
   After starting broadcasting musical composition A at step SP 102 , the radio station RS notifies this state to the associated information provision server KS, and then proceeds to the next step SP 103 . 
   At step SP 111 , the associated information provision server KS uses the musical composition information database  93  ( FIG. 4 ) to maintain a database of musical composition information associated with musical compositions. More specifically, the musical composition information includes titles and artist names concerning a plurality of types of musical compositions, names and numbers of CDs that record the corresponding musical compositions, and the like. It is necessary to provide the client terminal CT with musical composition information associated with musical composition A notified from the radio station RS. For this purpose, the associated information provision server KS updates the previous musical composition information to musical composition information associated with musical composition A, and then proceeds to the next step SP 112 . 
   At step SP 121 , the client terminal CT receives musical composition A broadcast by the radio station RS at step SP 101  so that the user can listen to it. At step SP 122 , the client terminal CT performs polling by sending an acquisition request for the musical composition information to the associated information provision server KS at an interval of 30 seconds. The musical composition information includes titles and artist names associated with musical composition A. The client terminal CT then proceeds to the next step SP 123 . 
   The associated information provision server KS prepares the musical composition information to be provided in advance. At step SP 112 , in response to the acquisition request from the client terminal CT, the associated information provision server KS provides the client terminal CT with that prepared musical composition information about musical composition A via the network  2 . The associated information provision server KS then proceeds to the next step SP 113 . 
   At step SP 123 , the client terminal CT uses the display  17  to display the musical composition information about musical composition A provided from the associated information provision server KS. Doing this allows the user to recognize the musical composition information such as titles and artist names about the musical composition A broadcast in the program. The client terminal CT then proceeds to the next step SP 124 . 
   At step SP 103 , the radio station RS stops broadcasting musical composition A. At step SP 104 , the radio station RS terminates the current program that broadcast musical composition A, starts broadcasting the next program, and then proceeds to the next step SP 105 . 
   At step SP 105 , the radio station RS starts the next broadcast and simultaneously sends a clear instruction to the associated information provision server KS. This aims at removing the musical composition information about musical composition A broadcast in the previous program from the other information maintained by the associated information provision server KS for provision. The radio station RS then proceeds to the next step SP 106 . 
   At step SP 113 , the associated information provision server KS removes the musical composition information about musical composition A from the other information maintained for provision. Doing so, the associated information provision server KS clears the musical composition information about musical composition A, and then proceeds to the next step SP 114 . 
   At step SP 124 , an interval of 30 seconds has passed since the most recent acquisition request. The client terminal CT re-issues an acquisition request for musical composition information to the associated information provision server KS. 
   At step SP 114 , the associated information provision server KS terminates the preceding program for broadcasting musical composition A and starts the next program. Almost at the same time, the associated information provision server KS clears the musical composition information about musical composition A broadcast in the preceding program from the other information to be provided. The associated information provision server KS provides the client terminal CT with empty musical composition information (null data) as the associated information, and then proceeds to the next step SP 115 . 
   At step SP 125 , the client terminal CT displays the null musical composition information on the display  17 . That is to say, nothing is displayed thereon. 
   Since nothing is displayed on the display  17 , the client terminal CT indirectly notifies the user that no musical composition is broadcast in the currently broadcast program. 
   At step SP 106 , the radio station RS starts broadcasting musical composition B in the current program. At step SP 107 , the radio station RS notifies the associated information provision server KS that musical composition B has started to be broadcast. 
   At step SP 113 , the associated information provision server KS already clears the musical composition information about musical composition A. Therefore, at step SP 115 , the associated information provision server KS reads the musical composition information about musical composition B from the musical composition information database  93 . The associated information provision server KS updates the read musical composition information as one to be provided, and then proceeds to the next step SP 116 . 
   At step SP 126 , the client terminal CT re-issues an acquisition request for the musical composition information to the associated information provision server KS. At step SP 116 , the associated information provision server KS provides the client terminal CT with the updated musical composition information about musical composition B. At step SP 127 , the client terminal CT acquires the musical composition information about musical composition B and displays it on the display  17 . 
   In this manner, the client terminal CT can acquire the musical composition information about musical composition A or B broadcast in the program from the associated information provision server KS while the radio station RS is broadcasting the program. It is possible to prevent the currently broadcast program and the musical composition information from being displayed with a time difference between them. 
   (1-9-2) Program Information Provision Sequence 
   With reference to  FIG. 12 , the following describes a process in which the associated information provision server KS uses a homepage to provide the client terminal CT with the associated information, i.e., information associated with programs broadcast from the radio station RS. In  FIGS. 11 and 12 , the associated information provision server KS authenticates user information sent from the client terminal CT in the manner similar to those described with reference to  FIGS. 8 and 10 . The specific authentication technique will be described in the second embodiment later. 
   At step SP 201 , the radio station RS starts broadcasting musical composition A in the current program, and then proceeds to the next step SP 202 . 
   After starting broadcasting musical composition A at step SP 202 , the radio station RS notifies this state to the associated information provision server KS, and then proceeds to the next step SP 203 . 
   At step SP 211 , the associated information provision server KS reads the musical composition information associated with musical composition A from the musical composition information database  93  ( FIG. 4 ). The associated information provision server KS is prepared to provide the client terminal CT with the musical composition information associated with musical composition A notified from the radio station RS. The associated information provision server KS updates the previously maintained musical composition information to that associated with musical composition A, and then proceeds to the next step SP 212 . 
   At step SP 221 , the client terminal CT receives musical composition A broadcast by the radio station RS at step SP 201  so that the user can listen to it. At step SP 222 , the client terminal CT performs polling by sending an acquisition request for the musical composition information to the associated information provision server KS at an interval of 30 seconds. The musical composition information includes titles and artist names associated with musical composition A. The client terminal CT then proceeds to the next step SP 223 . 
   The associated information provision server KS prepares the musical composition information to be provided in advance. At step SP 212 , in response to the acquisition request from the client terminal CT, the associated information provision server KS provides the client terminal CT with that prepared musical composition information about musical composition A via the network  2 . The associated information provision server KS then proceeds to the next step SP 213 . 
   At step SP 223 , the client terminal CT uses the display  17  to display the musical composition information about musical composition A provided from the associated information provision server KS. Doing this allows the user to recognize the musical composition information such as titles and artist names about the musical composition A broadcast in the current program. The client terminal CT then proceeds to the next step SP 224 . 
   At step SP 203 , the radio station RS stops broadcasting musical composition A. At step SP 204 , the radio station RS terminates the current program that broadcast musical composition A, starts broadcasting the next program, and then proceeds to the next step SP 205 . 
   At step SP 205 , the radio station RS starts the next broadcast and simultaneously notifies the associated information provision server KS that the next program has started to be broadcast. The radio station RS proceeds to the next step SP 206 . 
   The associated information provision server KS uses the musical composition information database  93  to store a plurality of musical composition information. Likewise, the associated information provision server KS uses the program information database  94  to store program information associated with a plurality of programs such as program names, DJ names, and the like. At step SP 213 , the associated information provision server KS reads the program information associated with the next program such as a program name, a DJ name, and the like from the program information database  94 . The associated information provision server KS then removes the musical composition information about musical composition A from the information to be provided. The associated information provision server KS updates the program information about the next program as information to be provided next, and then proceeds to the next step SP 214 . 
   At step SP 224 , an interval of 30 seconds has passed since the most recent acquisition request. The client terminal CT re-issues an acquisition request for musical composition information to the associated information provision server KS. 
   At step SP 214 , the associated information provision server KS maintains the program information associated with the next program as information to be provided next. In addition, the next program does not broadcast musical composition B yet. The associated information provision server KS provides the client terminal CT the program information about the next program as the associated information, and then proceeds to the next step SP 215 . 
   At step SP 225 , the client terminal CT uses the display  17  to display the program information associated with the next program such as the program name, the DJ name, and the like, and then proceeds to the next step SP 226 . 
   Though the radio station RS already starts broadcasting the next program, the program does not start broadcasting the musical composition yet. The client terminal CT displays the next program&#39;s program information provided from the associated information provision server KS until the program starts broadcasting the musical composition. 
   At step SP 206 , the radio station RS starts broadcasting musical composition B in the current program (next program). At step SP 207 , the radio station RS notifies the associated information provision server KS that musical composition B has started to be broadcast. 
   At step SP 215 , the associated information provision server KS reads the musical composition information about musical composition B from the musical composition information database  93 . The associated information provision server KS newly updates the musical composition information about musical composition B as one to be provided, and then proceeds to the next step SP 216 . 
   At step SP 226 , the client terminal CT re-issues an acquisition request for musical composition information to the associated information provision server KS at a polling interval, and then proceeds to the next step SP 227 . 
   At step SP 216 , the associated information provision server KS provides the client terminal CT with the updated musical composition information about musical composition B. At step SP 227 , the client terminal CT acquires the musical composition information about musical composition B and displays it on the display  17 . 
   The client terminal CT may issue an acquisition request for the musical composition information when the current program changes to the next one which broadcasts no musical composition yet. In such case, the client terminal CT can acquire the program information about the next program instead of the musical composition information and display the acquired program information on the display  17 . This prevents the display  17  from displaying nothing despite acquisition request for the musical composition information and notifies useful program information to the user who listens to the program instead of the musical composition information. 
   (1-10) Operations and Effects 
   According to the above-mentioned configuration, the associated information provision server KS in the information provision system  1  receives an acquisition request from the client terminal CT. At this time, the associated information provision server KS provides the client terminal CT with the musical composition information or the program information that is maintained to be supplied next. 
   In this case, the associated information provision server KS supplies the client terminal CT with the musical composition information associated with musical composition A broadcasted by the-radio station RS in the program. When the current program terminates and changes to the next, the associated information provision server KS receives a clear instruction from the radio station RS to remove the musical composition information from candidates to be provided. The associated information provision server KS provides the client terminal CT with null musical composition information. 
   When the current program terminates and changes to the next, the associated information provision server KS provides the client terminal CT with the program information such as a program name and a DJ name associated with the next program until musical composition B starts to be broadcast in that next program. 
   Upon reception of an acquisition request from the client terminal CT, the associated information provision server KS can provide the client terminal CT with the associated information and allow the client terminal CT to display this information. Specifically, the associated information comprises the musical composition information or program information that chronologically corresponds to the program broadcasted by the radio station RS. It is possible to always provide a user of the client terminal CT with associated information that matches the progress of the program. 
   According to the above-mentioned configuration, the associated information provision server KS in the information provision system  1  can ensure consistency between a program broadcasted from the radio station RS and associated information supplied from the associated information provision server KS. The associated information provision server KS can provide the associated information by realtime linking it with the program. 
   (2) SECOND EMBODIMENT 
   As the second embodiment, the following describes authentication methods between the client terminal  2  and the URL provision server  3  and between the client terminal  2  and the associated information provision server KS according to the first embodiment as mentioned above. 
   The method of providing the associated information according to the second embodiment is the same as that for the first embodiment and the description is omitted. A client terminal  1002  in  FIG. 13  according to the second embodiment corresponds to the client terminal CT in  FIG. 1  according to the above-mentioned first embodiment. A portal server  1003  in  FIG. 14  functions as an authentication server and corresponds to the URL provision server  3  in  FIG. 1 . A radio broadcast information delivery server  1006  in  FIG. 15  corresponds to the associated information provision server KS in  FIG. 1 . 
   (2-1) Functional Circuit Block Configuration of the Client Terminal 
   The following describes the hardware configuration of the client terminal  1002  using functional circuit blocks. As shown in  FIG. 13 , the client terminal  1002  has an operation input section  1020  comprising various operation buttons provided on the surface of the client terminal cabinet or a remote controller (not shown). When a user operates the operation input section  1020 , it detects the user operation and sends an input operation signal corresponding to the operation to an input processing section  1021 . 
   The input processing section  1021  is supplied with the input operation signal from the operation input section  1020 , converts the signal into a specific operation command, and sends it to a control section  1023  via a bus  1022 . 
   The control section  1023  is supplied with operation commands and control signals from circuits connected to the bus  1022 . Based on these operation commands and control signals, the control section  1023  controls operations of these circuits. 
   A display control section  1024  is supplied with video data via the bus  1022  and applies digital-analog conversion to the video data to generate an analog video signal. The display control section  1024  sends the resulting analog video signal to a display section  1025 . 
   The display section  1025  represents a display device such as a liquid crystal display and may be directly attached to the surface of the main unit cabinet or may be externally connected. 
   The display section  1025  is supplied with processing results from the control section  1023  and various video data as an analog video signal via the display control section  1024 . The display section  1025  displays a video based on the analog video signal. 
   An audio control section  1026  applies digital-analog conversion to audio data supplied via the bus  1022  and sends a resulting analog audio signal to a speaker  1027 . The speaker  1027  outputs audio based on the analog audio signal supplied from the audio control section  1026 . 
   An external recording media recording and reproducing section  1028  reads and reproduces content data from external recording media such as CDs and Memory Stick (registered trademark), and records targeted content data on the external recording media. Memory Stick comprises flash memory enclosed in a packaging case. 
   The external recording media recording and reproducing section  1028  reads video data as content data from an external recording medium and supplies the read video data to the display control section  1024  via the bus  1022 . 
   The display control section  1024  is supplied with the video data read as content data from the external recording medium by the external recording media recording and reproducing section  1028 . The display control section  1024  then converts the video data into an analog video signal and sends it to the display section  1025 . 
   The external recording media recording and reproducing section  1028  reads audio data as content data from the external recording medium and supplies the read audio data to the audio control section  1026  via the bus  1022 . 
   When the external recording media recording and reproducing section  1028  reads audio data as content data from the external recording medium, the audio control section  1026  converts the audio data into an analog audio signal and supplies it to the speaker  1027 . 
   When the external recording media recording and reproducing section  1028  reads the content data from the external recording medium, the control section  1023  sends that content data to a storage medium  1029  in the client terminal  1002  via the bus  1022 . The control section  1023  can store the content data in the storage medium  1029 . Storing content data in the storage medium  1029  is also referred to as ripping. 
   When reading video data such as image data as content data from the storage medium  1029 , the control section  1023  supplies the read video data to the display control section  1024  via the bus  1022 . 
   When reading audio data as content data from the storage medium  1029 , the control section  1023  supplies the read audio data to the audio control section  1026  via the bus  1022 . 
   In addition, the control section  1023  can read music data from the storage medium  1029  and transfers it to the external recording media recording and reproducing section  1028  which can then record the music data on the external recording medium. 
   A broadcast signal reception section  1030  receives radio broadcasting waves transmitted from radio stations and supplies them to the tuner section  1031 . 
   As mentioned above, the broadcast signal reception section  1030  receives radio broadcasting waves. Under the control of the control section  1023 , the tuner section  1031  extracts such radio broadcasting signals from the received radio broadcasting waves as to have a broadcasting frequency corresponding to the radio station specified from the operation input section  1020 , for example. The tuner section  1031  then applies specified reception processing to the extracted signals. The tuner section  1031  sends resulting audio data to the audio control section  1026  via the bus  1022 . 
   The audio control section  1026  converts the audio data supplied from the tuner section  1031  into an analog audio signal and sends this signal to the speaker  1027 . The speaker  1027  outputs the audio of the radio program broadcast from the radio station. In this manner, the user can listen to the radio program&#39;s audio. 
   The control section  1023  can record audio of radio programs. To do this, the control section  1023  sends audio data acquired by the tuner section  1031  to the storage medium  1029  for storage. 
   Further, the control section  1023  can connect to a specified network via a communication control section  1032  and a network interface  1033  in order. Consequently, the control section  1023  can access the portal server  1003 , a service provision server (e.g., the radio broadcast information delivery server  1006  to be described later), and the like on the network. In this manner, the client terminal can interchange various information and data with the portal server  1003 , the service provision server, and the like. 
   Compressed and encoded content data is received from the network via the network interface  1033  and the communication control section  1032  in order. Alternatively, compressed and encoded content data is read from the storage medium  1029  and external recording media. An encoder/decoder section  1034  decodes such content data and sends it to the audio control section  1026 . 
   Further, the encoder/decoder section  1034  compresses and encodes neither compressed nor encoded content data read from external recording media or audio data supplied from the tuner section  1031 . The encoder/decoder section  1034  sends the compressed and encoded content data to the storage medium  1029 . 
   Under the control of the control section  1023 , content data is compressed and encoded in the encoder/decoder section  1034  and is stored in the storage medium  1029 . 
   A copyright management section  1035  generates copyright management information corresponding to content data that is downloaded from the network via the network interface  1033  and the communication control section  1032  in order or is read from external recording media by the external recording media recording and reproducing section  1028 . 
   Under the control of the control section  1023 , the copyright management information generated in the copyright management section  1035  is associated with the content data and is registered to the recording medium  1029 . 
   The copyright management section  1035  is used to check out content data associated with the copyright management information from the storage medium  1029  to a specific external recording medium and to check in the content data associated with the copyright management information from the specific external recording medium to the storage medium  1029 . The copyright management section  1035  appropriately updates contents of the copyright management information corresponding to the content data to protect the copyright of the content data. 
   The client terminal receives XML (eXtensible Markup Language) or HTML (Hyper Text Markup Language) files from the network via the network interface  1033  and the communication control section  1032  in order. A page information generation section  1036  interprets page information of these files and generates video data to be displayed on the display section  1025 . The page information generation section  1036  then sends the generated video data to the display control section  1024 . 
   An authentication processing section  1037  performs authentication processes such as sending authentication information to the portal server  1003  and the service provision server on the network connected via the communication control section  1032  and the network interface  1033  in order. 
   An authentication information storage section  1038  stores authentication information needed for the authentication processing section  1037  to access the portal server  1003 , the service provision server, and the like. 
   A radio broadcasting display control section  1039  sends a request signal to the radio broadcast information delivery server  1006  via the communication control section  1032  and the network interface  1033  in order. This request signal is used to request information about the radio broadcast currently received by the user for listening. The radio broadcast information delivery server  1006  is one of service provision servers corresponding to the radio station that carries the radio broadcast being received. 
   As a result, the radio broadcasting display control section  1039  receives the radio broadcast information received from the networked radio broadcast information delivery server  1006  via the network interface  1033  and the communication control section  1032  in order. In addition, the radio broadcasting display control section  1039  sends the received radio broadcast information to the display control section  1024 . This allows the display section  1025  to display the radio broadcast information (equivalent to the associated information in the first embodiment) comprising a name, of the currently received radio program, a title and an artist name of the currently received musical composition, and the like. 
   (2-2) Portal Server Configuration 
   With reference to  FIG. 14 , the following describes the hardware configuration of the portal server  1003  using functional circuit blocks. A control section  1050  in the portal server  1003  controls operations of circuits connected via a bus  1051 . 
   Under the control of the control section  1050 , a communication control section  1052  interchanges various information with the client terminal  1002 , the service provision server, and the like via a network interface  1053 . 
   A customer database section  1054  registers customer information comprising user ID (identification) information and associated password information of a user who has completed a contract with a service provider of the information provision system. 
   A page information storage section  1055  stores page information and the like managed by the information provision system&#39;s service provider. 
   The page information is written in languages such as XML and includes URL (Uniform Resource Locator) information to access the service provision server and the like. 
   An authentication processing section  1056  receives the user ID information and the password information sent from the client terminal  1002  via the network interface  1053  and the communication control section  1052  in order. The authentication processing section  1056  then performs a user authentication process to confirm whether or not the customer database section  1054  stores the received user ID information and password information as the customer information. 
   Upon completion of the user authentication process, the authentication processing section  1056  issues portal authentication result information (authentication session ID information to be described later) indicating the result of the user authentication process. The authentication processing section  1056  temporarily stores the issued portal authentication result information in the authentication information storage section  1057 . 
   Let us assume that the user is authenticated to be a registered user as a result of the user authentication process by the authentication processing section  1056 . In this case, the control section  1050  sends page information about a contractor page stored in the page information storage section  1055  as well as the portal authentication result information to the client terminal  1002  via the communication control section  1052  and the network interface  1053  in order. 
   Next, let us assume that the user is not authenticated to be a registered user as a result of the user authentication process by the authentication processing section  1056 . In this case, the control section  1050  may be configured to send authentication error information as well as unsuccessful authentication notification page information indicating the unsuccessful authentication to the client terminal  1002  via the communication control section  1052  and the network interface  1053  in order. The unsuccessful authentication notification page information is stored in the page information storage section  1055 . 
   As a result of performing authentication processes for the user from the service provision server and the like, the authentication processing section  1056  receives portal authentication result information (authentication ticket to be described later) via the network interface  1053  and the communication control section  1052  in order. The portal authentication result information is acquired and sent from the user&#39;s client terminal  1002 . Then, the authentication processing section  1056  compares the received portal authentication result information with the portal authentication result information that is temporarily stored in the authentication information storage section  1057  corresponding to the user. 
   The authentication processing section  1056  performs a confirmation process as an authentication process for the portal authentication result information received from the service provision server and the like. Specifically, the authentication processing section  1656  confirms whether or not the portal authentication result information is authenticated. The authentication processing section  1056  then returns confirmation result information indicating a confirmation result to the service provision server and the like via the communication control section  1052  and the network interface  1053  in order. 
   A frequency information storage section  1058  stores the following associated with each other: an area code such as a postal guide number capable of specifying an area; frequency information indicating broadcast frequencies for radio broadcasts receivable in the area indicated by the area code; a name of a radio station (hereafter referred to as a radio station name) to broadcast the radio broadcast; and a call sign as identification information unique to each radio station. 
   A URL storage section  1059  stores the following associated with each other: a call sign for radio broadcast corresponding to each radio station; and URL information capable of acquiring radio broadcast information (hereafter referred to specifically as now-on-air information). This information concerns a currently broadcast radio program provided by the radio station corresponding to the call sign and comprises a name of the radio program, a title of the musical composition currently broadcast in the radio program, and the like. 
   (2-3) Functional Circuit Block Configuration of the Radio Broadcast Information Delivery Server 
   With reference to  FIG. 15 , the following describes the hardware configuration of the radio broadcast information delivery server  1006 , i.e., one of service provision servers, using functional circuit blocks. A control section  1110  in the radio broadcast information delivery server  1006  controls operations of circuits connected via a bus  1111 . 
   Under the control of the control section  1110 , a communication control section  1112  interchanges various information with the client terminal  1002 , the portal server  1003 , and the like via a network interface  1113 . 
   A customer database section  1114  registers customer information comprising user ID information and associated password information of a user who has completed a contract with a service provider of the radio broadcast information delivery server  1006 . The authentication processing section  1115  may have a function to authenticate users based on the portal authentication result information that is sent from the client terminal  1002  and is issued by the portal server  1003 . In such case, the customer database section  1114  may not be provided. 
   There is provided radio broadcast information called on-air-list information. This information is managed by the radio broadcast information delivery server  1006  and concerns the radio program already broadcast by the radio station corresponding to the radio broadcast information delivery server  1006 . A page information storage section  1116  stores, for example, page information about an on-air-list information delivery page used to acquire the on-air-list information. 
   Page information about the on-air-list information delivery page is written in a language such as XML. There is provided an input box or the like that allows a user of the client terminal  1002  to enter retrieval keys for intended on-air-list information. For example, retrieval keys include broadcast date information, names, and the like of radio programs. 
   An on-air-list information storage section  1117  stores the on-air-list information generated in a list format. The on-air-list information includes: the name of the radio program already broadcasted from the radio station corresponding to the radio broadcast information delivery server  1006 ; program broadcast start time, program broadcast end time, and the like; and title and artist name of a musical composition broadcasted in the radio program, musical composition broadcast start time, and the like. 
   The control section  1110  receives a page information acquisition request signal to request the page information about the on-air-list information delivery page from the client terminal  1002  via the network interface  1113  and the communication control section  1112  in order. Corresponding to the received page information acquisition request signal, the control section  1110  sends the page information about the on-air-list information delivery page stored in the page information storage section  1116  to the client terminal  1002  via the communication control section  1112  and the network interface  1113  in order. 
   After the retrieval key is entered for the page information about the on-air-list information delivery page from the client terminal  1002 , the retrieval section  1118  stores the retrieval key to retrieve the intended on-air-list information. When an on-air-list information request signal is transmitted to request download of the on-air-list information, the retrieval section  1118  receives the on-air-list information request signal via the network interface  1113  and the communication control section  1112  in order. The retrieval section  1118  then extracts the retrieval key from the received on-air-list information request signal. 
   Based on the retrieval key, the retrieval section  1118  searches the entire on-air-list information in the on-air-list information storage section  1117  for the targeted on-air-list information within a specified range corresponding to the retrieval condition indicated by the retrieval key. 
   As a result, the control section  1110  sends the retrieved targeted on-air-list information to the client terminal  1002  via the communication control section  1112  and the network interface  1113  in order. 
   A now-on-air information storage section  1119  stores radio broadcast information called now-on-air information. This information comprises: program name, program broadcast start time, and program broadcast end time of a radio program currently broadcasted from the radio station corresponding to the radio broadcast information delivery server  1006 ; and title, artist name, musical composition broadcast start time, and the like of a musical composition currently broadcasted in the radio program. 
   The client terminal  1002  sends not only a now-on-air information request signal to request to acquire the now-on-air information, but also user ID information and password information of the user who uses the client terminal  1002 . The authentication processing section  1115  receives these pieces of information via the network interface  1113  and the communication control section  1112  in order. The authentication processing section  1115  then performs the user authentication process to confirm whether or not the received user ID information and password information are registered as the customer information in the customer database section  1114 . 
   Further, the authentication processing section  1115  uses a user authentication technique different from the user authentication process that uses the user ID information and the password information. That is to say, the client terminal  1002  sends the portal authentication result information (authentication ticket to be described later) that is issued from the portal server  1003 . The authentication processing section  1115  receives this information via the network interface  1113  and the communication control section  1112  in order. The authentication processing section  1115  then sends the received portal authentication result information to the portal server  1003  via the communication control section  1112  and the network interface  1113  in order. 
   After the authentication processing section  1115  sends the portal authentication result information to the portal server  1003 , the portal server  1003  returns confirmation result information as a result of performing the authentication process (i.e., the above-mentioned confirmation process) corresponding to the portal authentication result information. The authentication processing section  1115  receives the confirmation result information via the network interface  1113  and the communication control section  1112  in order. Based on the received confirmation result information, the authentication processing section  1115  determines whether or not the user is a registered user who has completed a contract with the service provider of a music related service provision system  1000 . 
   After terminating the user authentication process, the authentication processing section  1115  issues server authentication result information (service session ID information to be described later) indicating the result of the user authentication process. 
   Let us assume that the user is authenticated to be a registered user as a result of the user authentication process performed by the authentication processing section  1115 . In this case, the control section  1110  sends the now-on-air information stored in the now-on-air information storage section  1119  as well as the server authentication result information to the client terminal  1002  via the communication control section  1112  and the network interface  1113  in order. 
   By contrast, let us assume that the user is not authenticated to be a registered user as a result of the user authentication process performed by the authentication processing section  1115 . In this case, the control section  1110  sends authentication error information as well as unsuccessful authentication notification page information to the client terminal  1002  via the communication control section  1112  and the network interface  1113  in order. The unsuccessful authentication notification page information is stored in the page information storage section  1116  and indicates unsuccessful authentication. 
   In this manner, the control section  1110  functions in response to a request to acquire the now-on-air information from the user as follows. When the user is authenticated to be a registered user, the control section  1110  provides the now-on-air information. When the user is not authenticated to be a registered user, however, the control section  1110  prevents the user from receiving radio broadcast information delivery services provided by the radio broadcast information delivery server  1006  such as the now-on-air information delivery service. 
   The authentication information storage section  1120  temporarily stores the server authentication result information issued from the authentication processing section  1115 . The authentication information storage section  1120  also stores various authentication information needed when the authentication processing section  1115  authenticates a user of the client terminal  1002 . 
   (2-4) Process Overview of the Servers 
   With reference to sequence charts in  FIGS. 16 through 19 , the following outlines processes performed between the client terminal  1002  and the portal server  1003  and processes performed between the client terminal  1002  and each service provision server. 
   (2-4-1) User Authentication Process Between the Client Terminal  1002  and the Portal Server  1003   
   With reference to  FIG. 16 , the following describes a user authentication process performed between the client terminal  1002  and the portal server  1003 . 
   The control section  1023  corresponds to the client terminal  1002  for the user who contracts with the information provision system&#39;s service provider. For example, the user performs an operation to turn on the client terminal  1002 . Alternatively, the user presses a specific operation button on the operation input section  1020 . In response to such operation, the operation input section  1020  recognizes an operation input signal. The input processing section  1021  converts this signal into an operation command. The control section  1023  is supplied with this command and starts an authentication request process. 
   After starting the authentication request process, the control section  1023 , at step SP 1000 , generates a connection request signal containing the authentication session ID information and the like temporarily stored in the authentication information storage section  1038 . The control section  1023  sends the generated connection request signal to the portal server  1003  via the communication control section  1032  and the network interface  1033  in order. 
   The client terminal  1002  establishes a communication connection with the portal server  1003  to perform various processes such as the user authentication process. Each time this communication connection is established, the portal server  1003  issues the authentication session ID information as identification information to identify respective communication connection states (i.e., sessions). 
   For the use with the user authentication process and the like, the authentication session ID information is assigned with a specified valid period (e.g., approximately one minute) with reference to the time of issuance from the portal server  1003 . 
   The client terminal  1002  acquires the authentication session ID information from the portal server  1003 . There may be a case where the client terminal  1002  cannot supply the authentication session ID information to the portal server  1003  within the valid period. In such case, the portal server  1003  determines cancellation of the communication connection state specified by the authentication session ID information. 
   In this manner, the portal server  1003  prevents the previously issued authentication session ID information from being falsely used by a user not contracted with the service provider of the music related service provision system  1 . 
   The authentication information storage section  1038  temporarily stores the authentication session ID information. This authentication session ID information was issued by the portal server  1003  that established communication connection with the client terminal  1002  to perform the user authentication process and the like. 
   The client terminal  1002  sends a connection request signal. In response to this, at step SP 1001 , the control section  1050  of the portal server  1003  receives the connection request signal via the network interface  1053  and the communication control section  1052  in order. The received connection request signal contains the authentication session ID information and the like. The control section  1050  sends the authentication session ID information and the like to the authentication processing section  1056 . 
   Under the control of the control section  1050 , the authentication processing section  1056  performs the user authentication process based on the authentication session ID information and the like received as the connection request signal from the client terminal  1002 . 
   As a result, the authentication processing section  1056  may not be able to authenticate the user of the client terminal  1002  to be a registered user due to expiration of the valid period specified in the authentication session ID information and the like received from the client terminal  1002 . In such case, the control section  1050  sends the authentication error information indicating an authentication error to the client terminal  1002  via the communication control section  1052  and the-network interface  1053  in order. 
   At step SP 1002 , the control section  1023  of the client terminal  1002  receives the authentication error information sent from the portal server  1003  via the network interface  1033  and the communication control section  1032  in order. In response to this, the control section  1023  reads the user ID information, the password information, and the like stored in the authentication information storage section  1038 . The control section  1023  sends the read user ID information, password information, and the like to the portal server  1003  via the communication control section  1032  and the network interface  1033  in order. 
   At step SP 1003 , the control section  1050  of the portal server  1003  receives the user ID information, the password information, and the like sent from the client terminal  1002  via the network interface  1053  and the communication control section  1052  in order. The control section  1050  sends these pieces of information to the authentication processing section  1056 . 
   Under the control of the control section  1050 , the authentication processing section  1056  performs the user authentication process. Specifically, the authentication processing section  1056  checks if the received user ID information, password information, and the like are included in the customer information registered to the customer database section  1054 . 
   As a result, the authentication processing section  1056  may authenticate the user of the client terminal  1002  to be a registered user. In this case, under the control of the control section  1050 , the authentication processing section  1056  issues the portal authentication result information, i.e., the authentication session ID information and the like about communication connection state between the client terminal  1002  and the portal server  1003  at this time. In addition, the authentication processing section  1056  temporarily stores the authentication session ID information and the like in the authentication information storage section  1057 . 
   After the authentication processing section  1056  issued the authentication session ID information and the like to the client terminal  1002 , the control section  1050  sends these pieces of information to the client terminal  1002  via the communication control section  1052  and the network interface  1053  in order. 
   At step SP 1004 , the control section  1023  of the client terminal  1002  receives the authentication session ID information and the like sent from the portal server  1003  via the network interface  1033  and the communication control section  1032  in order. The control section  1023  then sends the received authentication session ID information and the like to the authentication processing section  1037 . 
   Under the control of the control section  1023 , the authentication processing section  1037  temporarily stores the received authentication session ID information and the like in the authentication information storage section  1038 . 
   The control section  1023  receives the page information acquisition request signal from the portal server  1003  to request the portal server  1003  for the page information. The control section  1023  sends the received signal together with the authentication session ID information and the like temporarily stored in the authentication information storage section  1038  to the portal server  1003  via the communication control section  1032  and the network interface  1033  in order. 
   At step SP 1005 , the control section  1050  of the portal server  1003  receives the page information acquisition request signal, the authentication session ID information, and the like sent from the client terminal  1002  via the network interface  1053  and the communication control section  1052  in order. The control section  1050  sends the received authentication session ID information and the like to the authentication processing section  1056 . 
   Under the control of the control section  1050 , the authentication processing section  1056  performs the user authentication process. Specifically, the authentication processing section  1056  compares the received authentication session ID information and the like with the authentication session ID information and the like that were issued to the client terminal  1002  at the above-mentioned step SP 1003  and were temporarily stored in the authentication information storage section  1057 . 
   As a result, at step SP 1006 , the authentication processing section  1056  authenticates the user of the client terminal  1002  to be a registered user. The authentication processing section  1056  determines that the terminal  1002  issued the valid acquisition request for the page information. The authentication processing section  1056  extends the valid period for the authentication session ID information and the like issued to the client terminal  1002 . 
   At this time, the control section  1050  reads the user-requested page information from the page information storage section  1055 . The control section  1050  sends the read page information, the authentication session ID information, and the like to the client terminal  1002  via the communication control section  1052  and the network interface  1053  in order. At this time, the authentication session ID information and the like are assigned with the valid period extended by the authentication processing section  1056 . 
   At step SP 1007 , the control section  1023  of the client terminal  1002  receives the page information sent from the portal server  1003  and the authentication session ID information with the extended valid period and the like via the network interface  1033  and the communication control section  1032  in order. The control section  1023  sends the received page information to the page information generation section  1036  and sends the authentication session ID information with the extended valid period and the like to the authentication processing section  1037 . 
   Based on the page information supplied from the control section  1023 , the page information generation section  1036  generates video data embedded with links to the service provision servers. The page information generation section  1036  sends the generated video data to the display control section  1024 . 
   The display control section  1024  applies a digital-analog conversion process to the video data supplied from the page information generation section  1036 . The display control section  1024  then sends the converted analog video signal to the display section  1025 . As a result, the display section  1025  displays the page of the portal server  1003  as a video based on the analog video signal. 
   The authentication processing section  1037  updates the authentication session ID information and the like temporarily stored at the above-mentioned step SP 1004  to the authentication session ID information with the extended valid period and the like as follows. Under the control of the control section  1023 , the authentication processing section  1037  temporarily stores the authentication session ID information with the extended valid period and the like received from the portal server  1003  in the authentication information storage section  1038  so as to overwrite the authentication session ID information having the valid period not extended and the like. 
   (2-4-2) User Authentication Process Between the Client Terminal  1002  and the Service Provision Server 
   With reference to  FIG. 17 , the following describes the user authentication process performed between the client terminal  1002  and each service provision server. 
   Actually, there are provided a plurality of service provision servers corresponding to provided services such as the radio broadcast information delivery server  1006 , a music data delivery server (not shown), and the like. The same user authentication process is performed between the client terminal  2  and whichever of these service provision servers. 
   For this reason, each service provision server comprises the components needed to perform the user authentication process such as the control section, the authentication processing section, the page information storage section, the authentication information storage section, the communication control section, and the network interface. For example, the radio broadcast information delivery server comprises the control section  1110 , the authentication processing section  1115 , the page information storage section  1116 , the authentication information storage section  1116 , the communication control section  1112 , and the network interface  1113 . 
   In one case, the user authentication process is performed when the client terminal  1002  accesses the service provision servers according to links in the page information acquired from the portal server  1003 . In another case, the user authentication process is performed when the client terminal  1002  accesses the service provision servers according to the URL information and the like already registered as bookmarks. In either case, the user authentication process is performed in the same procedure. 
   In consideration for this, the following describes the user authentication process in detail. 
   At step SP 1010 , the control section  1023  of the client terminal  1002  follows the URL information embedded as links in the page information or the URL information and the like already registered as bookmarks. The control section  1023  then sends the page information acquisition request signal as well as the service session ID information and the like read from the authentication information storage section  1038  to the service provision server via the communication control section  1032  and the network interface  1033  in order. The page information acquisition request signal requests to acquire the page information about the service provision page, e.g., the on-air-list information delivery page for the radio broadcast information delivery server. 
   The client terminal  1002  establishes a communication connection with each service provision server to perform various processes such as the user authentication process. Each time this communication connection is established, the service provision server accessed by the client terminal  1002  issues the service session ID information as identification information to identify respective communication connection states (i.e., sessions). 
   For the use with the user authentication process and the like, the service session ID information, like the authentication session ID information, is assigned with a specified valid period (e.g., approximately one minute) with reference to the time of issuance from each service provision server. 
   The client terminal  1002  acquires the service session ID information from each service provision server. There may be a case where the client terminal  1002  cannot supply the service session ID information to the information-issuing service provision server within the valid period. In such case, the information-issuing service provision server determines cancellation of the communication connection state specified by the service session ID information. 
   In this manner, each service provision server prevents the previously issued service session ID information from being falsely used by a user not contracted with the service provider of the information provision system. 
   The authentication information storage section  1038  temporarily stores the service session ID information. This service session ID information was issued by the access destination service provision server that established communication connection with the client terminal  1002  to perform the user authentication process and the like. 
   At step SP 1011 , the service provision server&#39;s control section receives the page information acquisition request signal, the service session ID information, and the like sent from the client terminal  1002  via the network interface and the communication control section in order. The control section sends the received service session ID information and the like to the authentication processing section. 
   Under the control of the control section, the authentication processing section performs the user authentication process. Specifically, the authentication processing section compares the received service session ID information and the like with the service session ID information and the like temporarily stored in the authentication information storage section. 
   As a result, the authentication processing section may not be able to authenticate the user of the client terminal  1002  to be a registered user, e.g., due to expiration of the valid period for the service session ID information received from the client terminal  1002 . In such case, the authentication processing section determines that the client terminal  1002  issued an invalid acquisition request for the page information about the service provision page. 
   In this case, the control section sends authentication error information and a shop code to the client terminal  1002  via the communication control section and the network interface in order. The authentication error information indicates an authentication error. The shop code is provided as service identification information to identify the service provision server. 
   At step SP 1012 , the control section  1023  of the client terminal  1002  receives the authentication error information and the shop code sent from the service provision server via the network interface  1033  and the communication control section  1032  in order. According to the received authentication error information, the control section  1023  determines that the service provision server does not authenticate the user as a registered user. In addition, the control section  1023  temporarily stores the shop code received from the service provision server in the authentication information storage section  1038 . 
   The control section  1023  generates an authentication ticket issuance request signal that requests the portal server  1003  to issue an authentication ticket for access to the service provision server. The control section  1023  then sends the generated authentication ticket issuance request signal, the service provision server&#39;s shop code, the authentication session ID information, and the like to the portal server  1003  via the communication control section  1032  and the network interface  1033  in order. It should be noted that the authentication session ID information and the like are already received from the portal server  1003  and are temporarily stored in the authentication information storage section  1038 . 
   At step SP 1013 , the control section  1050  of the portal server  1003  receives the authentication ticket issuance request signal, the shop code, the authentication session ID information, and the like sent from the client terminal  1002  via the network interface  1053  and the communication control section  1052  in order. The control section  1050  then sends these pieces of information to the authentication processing section  1056 . 
   Under the control of the control section  1050 , the authentication processing section  1056  performs the user authentication process. Specifically, the authentication processing section  1056  compares the authentication session ID information and the like with the authentication session ID information and the like temporarily stored in the authentication information storage section  1057 . 
   As a result, the authentication processing section  1056  may not be able to authenticate the user of the client terminal  1002  to be a registered user, e.g., due to expiration of the valid period for the authentication session ID information received from the client terminal  1002 . In such case, the authentication processing section  1056  determines that the client terminal  1002  issued an invalid acquisition request for the authentication ticket. 
   In this case, the control section  1050  sends authentication error information indicating an authentication error to the client terminal  1002  via the communication control section  1052  and the network interface  1053  in order. 
   By contrast, there may be a case where the valid period still takes effect for the authentication session ID information received from the client terminal  1002 . In such case, the authentication processing section  1056  authenticates the user of the client terminal  1002  to be a registered user. The authentication processing section  1056  determines that the client terminal  1002  issues a valid request for the authentication ticket. In this case, the control section  1050  returns to step SP 1018  to be described later. 
   At step SP 1014 , the control section  1023  of the client terminal  1002  receives the authentication error information sent from the portal server  1003  via the network interface  1033  and the communication control section  1032  in order. The control section  1023  then reads the user ID information, the password information, and the like stored in the authentication information storage section  1038 . In addition, the control section  1023  sends these pieces of information to the portal server  1003  via the communication control section  1032  and the network interface  1033  in order. 
   At step SP 1015 , the control section  1050  of the portal server  1003  receives the user ID information, the password information, and the like sent from the client terminal  1002  via the network interface  1053  and the communication control section  1052  in order. The control section  1050  then sends these pieces of information to the authentication processing section  1056 . 
   Under the control of the control section  1050 , the authentication processing section  1056  performs the user authentication process. Specifically, the authentication processing section  1056  checks whether or not the customer information registered to the customer database section  1054  contains the received user ID information, the password information, and the like. 
   As a result, the authentication processing section  1056  authenticates the user of the client terminal  1002  to be a registered user. Under the control of the control section  1050 , the authentication processing section  1056  issues the portal authentication result information, i.e., the authentication session ID information and the like about the state of communication connection between the client terminal  1002  and the portal server  1003  at the present time. The authentication processing section  1056  temporarily stores the issued authentication session ID information and the like in the authentication information storage section  1057 . 
   After the authentication processing section  1056  issues the authentication session ID information and the like to the client terminal  1002 , the control section  1050  sends the authentication session ID information and the like to the client terminal  1002  via the communication control section  1052  and the network interface  1053  in order. 
   At step SP 1016 , the control section  1023  of the client terminal  1002  receives the authentication session ID information and the like sent from the portal server  1003  via the network interface  1033  and the communication control section  1032  in order. The authentication processing section  1037  temporarily stores the received authentication session ID information and the like in the authentication information storage section  1038 . 
   The control section  1023  generates an authentication ticket issuance request signal that re-requests the portal server  1003  to issue an authentication ticket. The control section  1023  sends the generated authentication ticket issuance request signal as well as the shop code temporarily stored in the authentication information storage section  1038  and the authentication session ID information and the like temporarily stored at this time to the portal server  1003  via the communication control section  1032  and the network interface  1033  in order. 
   According to the embodiment, the client terminal  1002  temporarily stores the shop code in the authentication information storage section  1038 . The present invention is not limited thereto. When performing the process at steps SP 1012  through SP 1016 , the client terminal  1002  can sequentially exchange the shop code with the portal server  1003 . In this manner, the client terminal  1002  need not temporarily store the shop code in the authentication information storage section  1038 . Nevertheless, it is possible to send the shop code to the portal server  1003  at step SP 1016 . 
   At step SP 1017 , the control section  1050  of the portal server  1003  receives the authentication ticket issuance request signal, the shop code, the authentication session ID information, and the like sent from the client terminal  1002  via the network interface  1053  and the communication control section  1052  in order. The control section  1050  sends the received authentication ticket issuance request signal and the like to the authentication processing section  1056 . 
   Under the control of the control section  1050 , the authentication processing section  1056  performs the user authentication process. Specifically, the authentication processing section  1056  compares the received authentication session ID information and the like with the authentication session ID information and the like temporarily stored in the authentication information storage section  1057 . 
   As a result, there may be a case where the valid period still takes effect for the authentication session ID information and the like received from the client terminal  1002 . In such case, the authentication processing section  1056  authenticates the user of the client terminal  1002  to be a registered user. The authentication processing section  1056  determines that the client terminal  1002  issues a valid request for the authentication ticket. 
   At step SP 1018 , under the control of the control section  1050 , based on the shop code and the authentication ticket issuance request signal received from the client terminal  1002  at the above-mentioned step SP 1017 . The authentication processing section  1056  issues the portal authentication result information, i.e., an authentication ticket and the like to enable access to the service provision server indicated by the shop code. 
   Under the control of the control section  1050 , the authentication processing section  1056  temporarily stores the issued authentication ticket and the like in the authentication information storage section  1057 . In addition, the authentication processing section  1056  extends the valid period for the authentication session ID information and the like issued to the client terminal  1002 . 
   That is to say, the authentication processing section  1056  has issued the authentication ticket and the like and extended the valid period of the authentication session ID information and the like. Thereafter, the control section  1050  sends these authentication ticket and the like and authentication session ID information and the like to the client terminal  1002  via the communication control section  1052  and the network interface  1053  in order. 
   At step SP 1019 , the control section  1023  of the client terminal  1002  receives the authentication ticket and the like sent from the portal server  1003  and the authentication session ID information with the extended valid period via the network interface  1033  and the communication control section  1032  in order. The control section  1023  sends the received authentication session ID information to the authentication processing section  1037 . 
   The control section  1023  sends the authentication ticket and the like received from the portal server  1003  together with the authentication request signal to the service provision server via the communication control section  1032  and-the network interface  1033  in order. 
   At this time, under the control of the control section  1023 , the authentication processing section  1037  temporarily stores the authentication session ID information having the extended valid period received from the portal server  1003  in the authentication information storage section  1038  so as to overwrite the authentication session ID information having the valid period not extended. In this manner, the authentication processing section  1037  updates the authentication session ID information temporarily stored at the above-mentioned step SP 1016  to the authentication session ID information having the extended valid period. 
   At step SP 1020 , the control section of the service provision server receives the authentication request signal, the authentication ticket, and the like sent from the client terminal  1002  via the network interface and the communication control section in order. 
   The control section sends the authentication ticket and the like received from the client terminal  1002  together with an authentication ticket confirmation request signal for requesting confirmation of the authentication ticket and the like to the portal server  1003  via the communication control section and the network interface in order. 
   At step SP 1021 , the control section  1050  of the portal server  1003  receives the authentication ticket confirmation request signal, the authentication ticket, and the like sent from the service provision server via the network interface  1053  and the communication control section  1052  in order. The control section  1050  then sends the received authentication ticket confirmation request signal, the authentication ticket, and the like to the authentication processing section  1056 . 
   Under the control of the control section  1050 , the authentication processing section  1056  performs a confirmation process for the authentication ticket received from the service provision server in response to the authentication ticket confirmation request signal. Specifically, the authentication processing section  1056  compares the received authentication ticket and the like with the authentication ticket and the like temporarily stored in the authentication information storage section  1057 . 
   As a result, the authentication processing section  1056  confirms that the genuine authentication ticket and the like are received from the service provision server. In this case, the control section  1050  sends confirmation result information to the service provision server via the communication control section  1052  and the network interface  1053  in order. The confirmation result information indicates that the received authentication ticket and the like are confirmed to be genuine. 
   At step SP 1022 , the control section of the service provision server receives the confirmation result information sent from the portal server  1003  via the network interface and the communication control section in order. The control section sends the received confirmation result information to the authentication processing section. 
   Under the control of the control section, the authentication processing section responds to the confirmation result information and issues server authentication result information, i.e., service session ID information and the like about the state of communication connection between the client terminal  1002  and the service provision server at the present time. In addition, the authentication processing section temporarily stores the issued service session ID information and the like in the authentication information storage section. 
   After the authentication processing section issued the service session ID information and the like to the client terminal  1002 , the control section sends these pieces of information to the client terminal  1002  via the communication control section and the network interface in order. 
   At step SP 1023 , the control section  1023  of the client terminal  1002  receives the service session ID information and the like sent from the service provision server via the network interface  1033  and the communication control section  1032  in order. The authentication processing section  1037  temporarily stores the received service session ID information and the like in the authentication information storage section  1038 . 
   The control section  1023  sends the page information acquisition request signal, the service session ID information, and the like to the service provision server via the communication control section  1032  and the network interface  1033  in order. The page information acquisition request signal requests the page information about the service provision page. The service session ID information is temporarily stored in the authentication information storage section  1038 . 
   As step SP 1024 , the control section of the service provision server receives the page information acquisition request signal, the service session ID information, and the like sent from the client terminal  1002  via the network interface and the communication control section in order. The control section then sends the received service session ID information and the like to the authentication processing section. 
   Under the control of the control section, the authentication processing section performs the user authentication process. Specifically, the control section compares the received service session ID information and the like with the service session ID information and the like that are already issued to the client terminal  1002  at the above-mentioned step SP 1022  and are temporarily stored in the authentication information storage section. 
   As a result, there may be a case where the valid period still takes effect for the service session ID information and the like received from the client terminal  1002 . In such case, the authentication processing section authenticates the user of the client terminal  1002  to be a registered user. Then, the authentication processing section determines that the client terminal  1002  issues a valid request to acquire the page information about the service provision page. 
   The control section then proceeds to the next step SP 1025 . At step SP 1025 , the control section reads the page information about the user-requested service provision page from the page information storage section. In addition, the control section allows the authentication processing section to extend the valid period for the service session ID information and the like issued to the client terminal  1002 . 
   The control section sends the page information about the service provision page read from the page information storage section together with the service session ID information and the like to the client terminal  1002  via the communication control section and the network interface in order. The service session ID information and the like have the valid period extended by the authentication processing section. 
   At step SP 1026 , the control section  1023  of the client terminal  1002  receives the page information about the service provision page, the service session ID information having the extended valid period, from the service provision server via the network interface  1033  and the communication control section  1032  in order. The control section  1023  sends the page information about the received service provision page to the page information generation section  1036 . In addition, the control section  1023  sends the received service session ID information and the like to the authentication processing section  1037 . 
   Under the control of the control section  1023 , the authentication processing section  1037  temporarily stores the received service session ID information having the extended valid period in the authentication information storage section  1038  so as to overwrite the service session ID information having the valid period not extended and the like. In this manner, the authentication processing section  1037  updates the service session ID information and the like temporarily stored at the above-mentioned step SP 1023  to the service session ID information having the extended valid period. 
   Further, the page information generation section  1036  generates video data based on the page information about the service provision page. The page information generation section  1036  sends the generated video data to the display control section  1024 . 
   The display control section  1024  applies a digital-analog conversion process to the video data supplied from the page information generation section  1036 . The display control section  1024  then sends the converted analog video signal to the display section  1025 . As a result, the display section  1025  displays the service provision page as a video based on the analog video signal. 
   (2-4-3) Radio Broadcast Information Delivery Service Provision Processes 
   Referring now to  FIGS. 18 and 19 , the following describes a radio broadcast information delivery service provision process. This process takes place after termination of the user authentication process ( FIG. 17 ) performed between the client terminal  1002  and the service provision server as mentioned above. The process uses the page information about the service provision page acquired by the client terminal  1002  from the service provision server during the user authentication process. In this manner, a radio broadcast information delivery service is provided from the radio broadcast information delivery server, one of the service provision servers, for example. 
   (2-4-3-1) On-Air-List Information Delivery Service Provision Process 
   With reference to  FIG. 18 , the following describes the radio broadcast information delivery service provision process. During this process, the client terminal  1002  is provided with a radio broadcast information delivery service, especially an on-air-list information delivery service from the radio broadcast information delivery server  1006 . 
   For example, the user enters retrieval key to retrieve intended on-air-list information into an input box of the on-air-list information delivery page displayed-as, a video on the display section  1025 . The input processing section  1021  inputs a control command corresponding to a character string indicating the entered retrieval key. At step SP 1060 , the control section  1023  of the client terminal  1002  responds to the entered control command and generates an on-air-list information request signal to request download of the intended on-air-list information. 
   The control section  1023  sends the on-air-list information request signal together with the service session ID information and the like to the radio broadcast information delivery server  1006  via the communication control section  1032  and the network interface  1033  in order. The service session ID information and the like are already issued by the radio broadcast information delivery server  1006  and are temporarily stored in the authentication information storage section  1038 . 
   At step SP 1061 , the control section  1110  of the radio broadcast information delivery server  1006  receives the on-air-list information request signal, the service session ID information, and the like sent from the client terminal  1002  via the network interface  1113  and the communication control section  1112  in order. The control section  1110  then sends the received service session ID information and the like to the authentication processing section  1115 . 
   Under the control of the control section  1110 , the authentication processing section  1115  performs the user authentication process. Specifically, the authentication processing section  1115  compares the received service session ID information and the like with the service session ID information and the like temporarily stored in the authentication information storage section  1120 . 
   As a result, the authentication processing section  1115  may authenticate the user to be a registered user who requested the on-air-list information using the client terminal  1002 . In this case, the control section  1110  proceeds to the next step SP 1062 . 
   At step SP 1062 , based on the retrieval key stored in the on-air-list information request signal, the retrieval section  1118  searches the entire on-air-list information in the on-air-list information storage section  1117  for the targeted on-air-list information within a specified range corresponding to the retrieval condition indicated by the retrieval key. 
   Let us assume that the retrieval section  1118  retrieves the on-air-list information. The control section  1110  allows the authentication processing section  1115  to extend the valid period for the service session ID information and the like issued to the client terminal  1002 . The control section  1110  then proceeds to the next step SP 1063 . 
   At step SP 1063 , the control section  1110  reads the on-air-list information retrieved by the retrieval section  1118  from the on-air-list information storage section  1117 . In addition, the control section  1110  sends the read on-air-list information together with the service session ID information and the like to the client terminal  1002  via the communication control section  1112  and the network interface  1113  in order. At this time, the service session ID information has the valid period extended by the authentication processing section  1115 . 
   At step SP 1064 , the control section  1023  of the client terminal  1002  receives the on-air-list information sent from the radio broadcast information delivery server  1006 , the service session ID information having the extended valid period, and the like via the network interface  1033  and the communication control section  1032  in order. The control section  1023  sends the received on-air-list information to the page information generation section  1036 . In addition, the control section  1023  sends the service session ID information and the like received from the radio broadcast information delivery server  1006  to the authentication processing section  1037 . 
   Under the control of the control section  1023 , the authentication processing section  1037  temporarily stores the received service session ID information having the extended valid period in the authentication information storage section  1038  so as to overwrite the service session ID information having the valid period not extended. In this manner, the authentication processing section  1037  updates the contents of the service session ID information and the like temporarily stored in the authentication information storage section  1038 . 
   The page information generation section  1036  generates video data based on the on-air-list information supplied from the control section  1023 . The display control section  1024  converts the generated video data into an analog video signal and sends it to the display section  1025 . The display section  1025  displays the on-air-list information as a video based on the analog video signal. 
   In this manner, the client terminal  1002  can allow the user to acquire intended on-air-list information by using the radio broadcast information delivery service provided by the radio broadcast information delivery server  1006 . 
   (2-4-3-2) Now-On-Air Information Delivery Service Provision Process 
   With reference to  FIG. 19 , the following describes a radio broadcast information delivery service provision process. During this process, the client terminal  1002  is provided with a radio broadcast information delivery service, especially a now-on-air information delivery service from the radio broadcast information delivery server  1006 . 
   The radio broadcast information delivery server  1006  to supply now-on-air information is provided for each radio station (call sign). 
   Initially, the client terminal  1002  may not store URL information about the radio broadcast information delivery server  1006  corresponding to each radio station. 
   The following radio broadcast information delivery service provision process exemplifies a case where the portal server  1003  manages URL information about each radio broadcast information delivery server  1006  for each call sign. 
   According to the radio broadcast information delivery service provision process, the client terminal  1002  may need to automatically preset a broadcast frequency for each radio station. For this purpose, the client terminal  1002  requests the portal server  1003  for frequency information indicating that broadcast frequency. In such case, it is assumed that the authentication information storage section  1038  does not temporarily store the authentication session ID information and the like. Consequently, the client terminal  1002  first needs to send the user ID information, the password information, and the like to the portal server  1003 . 
   When the input processing section  1021  inputs an operation command to request to automatically preset the broadcast frequency of each radio station. In response to this command, at step SP 1070 , the control section  1023  of the client terminal  1002  sends a frequency information request signal to request to acquire frequency information about a broadcast frequency which each radio station can receive. The control section  1023  sends the frequency information request signal together with an area code input by the user, the user ID information, the password information, and the like stored in the authentication information storage section  1038  to the portal server  1003  via the communication control section  1032  and the network interface  1033  in order. 
   At step SP 1071 , the control section  1050  of the portal server  1003  receives the frequency information request signal, the area code, the user ID information, the password information, and the like sent from the client terminal  1002  via the network interface  1053  and the communication control section  1052  in order. Of these pieces of information, the control section  1050  sends the user ID information, the password information, and the like to the authentication processing section  1056 . 
   Under the control of the control section  1050 , the authentication processing section  1056  performs the user authentication process. Specifically, the authentication processing section  1056  compares the received user ID information, the password information, and the like with the customer information registered in the customer database section  1054 . 
   As a result, the authentication processing section  1056  may authenticate the user of the client terminal  1002  to be a registered user. Further, the authentication processing section  1056  may determine that the client terminal  1002  issued a valid request to acquire the frequency information. Under the control of the control section  1050 , the authentication processing section  1056  issues the authentication session ID information and the like about the state of communication connection between the client terminal  1002  and the portal server  1003  at the present time. The authentication processing section  1056  temporarily stores the issued authentication session ID information and the like in the authentication information storage section  1057 . 
   The control section  1050  then proceeds to the next step SP 1072 . At step SP 1072 , the control section  1050  performs a search based on the area code received from the client terminal  1002 . That is to say, the control section  1050  searches a list of a plurality of frequency information, radio station names, and call signs in the frequency information storage section  1058  for those corresponding to the area code and reads them in a list format. 
   The control section  1050  reads the frequency information, the radio station name, and the call sign in a list form from the frequency information storage section  1058  and sends them along with the authentication session ID information and the like to the client terminal  1002  via the communication control section  1052  and the network interface  1053  in order. The authentication session ID information and the like were issued to the client terminal  1002  by the authentication processing section  1056  at the above-mentioned step SP 1071 . 
   At step SP  1073 , the control section  1023  of the client terminal  1002  receives the list of frequency information, radio station name, and call sign sent from the portal server  1003  as well as the authentication session ID information and the like via the network interface  1033  and the communication control section  1032  in order. The control section  1023  sends the authentication session ID information and the like received from the portal server  1003  to the authentication processing section  1037 . In addition, the control section  1023  sends the list of frequency information, radio station name, and call sign to the display control section  1024 . 
   Under the control of the control section  1023 , the authentication processing section  1037  temporarily stores the received authentication session ID information and the like in the authentication information storage section  1038 . 
   The display control section  1024  is supplied with the list of frequency information, radio station name, and call sign from the control section  1023  and sends the list to the display section  1025 . The display section  1025  thus displays the list. 
   At this time, the control section  1023  identifies a selection command supplied from the input processing section  1021 . Based on this command, the control section  1023  stores the selected frequency information, radio station name, and call sign as a preset in the storage medium  1029 . The control section  1023  then proceeds to the next step SP 1074 . 
   At step SP 1074 , the control section  1023  identifies a tuning control command supplied from the input processing section  1021 . Based on this command, the control section  1023  controls the tuner section  1031  so as to extract a radio broadcasting signal from radio broadcasting waves. This radio broadcasting signal should be used for the radio broadcast carried at the broadcast frequency corresponding to the tuning control command. 
   A broadcast signal reception section  30  receives radio broadcasting waves of these radio broadcasting waves, the tuner section  1031  extracts the radio broadcasting signal carried at the broadcast frequency. The tuner section  1031  applies specified reception processes such as decoding to the extracted radio broadcasting signal. As a result, audio data is generated. The tuner section  1031  sends this audio data to the audio control section  1026 . 
   The audio control section  1026  converts the audio data supplied from the tuner section  1031  into an analog audio signal. Then, the audio control section  1026  outputs the analog audio signal to the speaker  1027 . The speaker  1027  thus outputs audio of the selected radio program. 
   At step SP 1075 , under the control of the control section  1023 , the radio broadcasting display control section  1039  reads a call sign from the storage medium  1029 . This call sign is stored correspondingly to the frequency information indicating the broadcast frequency corresponding to the above-mentioned tuning control command. The radio broadcasting display control section  1039  sends the read call sign to the portal server  1003  via the communication control section  1032  and the network interface  1033  in order. Likewise, the radio broadcasting display control section  1039  sends authentication session ID information (alternatively, user ID information and password information) and the like temporarily stored in the authentication information storage section  1038 . 
   At step SP 1076 , the control section  1050  of the portal server  1003  receives the call sign, the authentication session ID information (alternatively, user ID information and password information), and the like sent from the client terminal  1002  via the network interface  1053  and the communication control section  1052  in order. The control section  1050  sends the received authentication session ID information (alternatively, user ID information and password information) and the like to the authentication processing section  1056 . 
   Under the control of the control section  1050 , the authentication processing section  1056  performs the user authentication process. Specifically, the authentication processing section  1056  compares the received authentication session ID information (alternatively, user ID information and password information) and the like with the authentication session ID information (alternatively, user ID information and password information) and the like temporarily stored in the authentication information storage section  1057 . 
   As a result, the authentication processing section  1056  may confirm that the authentication session ID information and the like are received from the client terminal  1002  within the valid period, for example. When the user sent the call sign using the client terminal  1002 , the authentication processing section  1056  may authenticate this user to be a registered user. In such case, the control section  1050  proceeds to the next step SP 1077 . 
   At step SP 1077 , the control section  1050  searches a plurality of URL information in the URL storage section  1059  for the URL information corresponding to the call sign based on the call sign received from the client terminal  1002 . 
   The control section  1050  allows the authentication processing section  1056  to extend the valid period of the authentication session ID information and the like issued to the client terminal  1002 . 
   The control section  1050  reads the retrieved URL information from the URL storage section  1059 . The control section  1050  sends the read URL information as well as the authentication session ID information and the like having the valid period extended by the authentication processing section  1056  to the client terminal  1002  via the communication control section  1052  and the network interface  1053  in order. Further, at step SP 1077 , the control section  1050  may send the state information as well as the URL information and authentication session ID. The state information indicates service states such as whether or not the radio broadcast information delivery server  1006  currently provides the now-on-air information service. 
   At step SP 1078 , the control section  1023  of the client terminal  1002  receives the URL information and the authentication session ID information having the extended valid period and the like sent from the portal server  1003  via the network interface  1033  and the communication control section  1032  in order. The control section  1023  sends the received authentication session ID information and the like to the authentication processing section  1037 . The control section  1023  sends the URL information to the radio broadcasting display control section  1039 . When receiving the state information from the portal server  1003 , the control section  1023  sends this state information to the radio broadcasting control section  1039 . 
   Under the control of the control section  1023 , the authentication processing section  1037  temporarily stores the received authentication session ID information having the extended valid period in the authentication information storage section  1038  to overwrite the authentication session ID information having the valid period not extended. In this manner, the authentication processing section  1037  updates the contents of the authentication session ID information and the like temporarily stored in the authentication information storage section  1038 . 
   Under the control of the control section  1023 , the radio broadcasting display control section  1039  temporarily stores the URL information supplied from the control section  1023  in the storage medium  1029  and the like correspondingly to the call sign stored in the storage medium  1029 . 
   When supplied with the state information from the control section  1023 , the radio broadcasting display control section  1039  sends the state information to the display section  1025  via the display control section  1024 . The display section  1025  is allowed to display the state information indicative of the service state in the radio broadcast information delivery server  1006 . 
   Under the control of the control section  1023 , the radio broadcasting display control section  1039  follows the URL information temporarily stored in the storage medium  1029  and the like. According to this information, the radio broadcasting display control section  1039  sends a now-on-air information request signal to the radio broadcast information delivery server  1006  via the communication control section  1032  and the network interface  1033  in order. The now-on-air information request signal requests to acquire the now-on-air information. Likewise, the radio broadcasting display control section  1039  sends the service session ID information and the like that are already received from the radio broadcast information delivery server  1006  and are temporarily stored in the authentication information storage section  1038 . 
   In the radio broadcast information delivery service provision process, at step SP 1078 , the client terminal  1002  sends the now-on-air information request signal, the service session ID information, and the like to the radio broadcast information delivery server  1006 . This process corresponds to the process at step SP 1010  in  FIG. 17  as mentioned above. 
   Therefore, in the radio broadcast information delivery service provision process, the process at step SP 1078  is followed by the user authentication process equivalent to steps SP 1011  through SP 1013  and steps SP 1018  through SP 1022  in the client terminal  1002 , the radio broadcast information delivery server  1006 , and the portal server  1003  as mentioned above with reference to  FIG. 17 . After these steps are performed in succession, control proceeds to the next step SP 1079 . 
   At step SP 1079 , under the control of the control section  1023 , the radio broadcasting display control section  1039  of the client terminal  1002  again follows the URL information temporarily stored in the storage medium  1029  and the like and sends a now-on-air information request signal to the radio broadcast information delivery server  1006  via the communication control section  1032  and the network interface  1033  in order. Likewise, the radio broadcasting display control section  1039  sends the service session ID information and the like that are already received from the radio broadcast information delivery server  1006  and are temporarily stored in the authentication information storage section  1038 . 
   At step SP 1080 , the control section  1110  of the radio broadcast information delivery server  1006  receives the now-on-air information request signal, the service session ID information, and the like sent from the client terminal  1002  via the network interface  1113  and the communication control section  1112  in order. The control section  1110  sends the received authentication session ID information and the like to the authentication processing section  1115 . 
   Under the control of the control section  1110 , the authentication processing section  1115  performs the user authentication process. Specifically, the authentication processing section  1115  compares the received service session ID information and the like with the service session ID information and the like temporarily stored in the authentication information storage section  1120 . 
   As a result, the authentication processing section  1115  may authenticate the user of the client terminal  1002  to be a registered user. In this case, the authentication processing section  1115  determines that the client terminal  1002  issued the valid request to acquire the now-on-air information. 
   When the authentication processing section  1115  authenticates the user of the client terminal  1002  to be a registered user. In this case, the control section  1110  extends the valid period of the service session ID information and the like issued to the client terminal  1002  by the authentication processing section  1115 , and then proceeds to the next step SP 1081 . 
   At step SP 1081 , the control section  1110  reads the now-on-air information from the now-on-air information storage section  1119 . The control section  1110  sends the read now-on-air information as well as the service session ID information and the like having the valid period extended by the authentication processing section  1115  to the client terminal  1002  via the communication control section  1112  and the network interface  1113  in order. 
   At step SP 1082 , the control section  1023  of the client terminal  1002  receives the now-on-air information and the service session ID information and the like having the extended valid period sent from the radio broadcast information delivery server  1006  via the network interface  1033  and the communication control section  1032  in order. The control section  1023  sends the received service session ID information and the like to the authentication processing section  1037 . The control section  1023  sends the now-on-air information to the radio broadcasting display control section  1039 . 
   Under the control of the control section  1023 , the authentication processing section  1037  temporarily stores the received service session ID information having the extended valid period and the like in the authentication information storage section  1038  to overwrite the service session ID information having the valid period not extended. In this manner, the authentication processing section  1037  updates the contents of the service session ID information and the like temporarily stored in the authentication information storage section  1038 . 
   Further, the radio broadcasting display control section  1039  sends the now-on-air information supplied from the control section  1023  to the display section  1025  via the display control section  1024 . In this manner, the display section  1025  is allowed to display the now-on-air information concerning the radio program in the currently received radio broadcast. 
   In the radio broadcast information delivery service provision process, the client terminal  1002  thereafter periodically repeats the acquisition request for now-on-air information at step SP 1079 . The radio broadcast information delivery server  1006  receives the acquisition request from the client terminal  1002  and successively performs the process at steps SP 1080  and SP 1081 . 
   In this manner, the client terminal  1002  can realtime update the now-on-air information and display it on the display section  1025  of the client terminal  1002 . For example, the now-on-air information includes the name of the currently received radio program, the program broadcast start time, the program broadcast end time, the title and artist name of a musical composition currently played in the radio program, and the musical composition broadcast start time. 
   According to the above-mentioned configuration, the second embodiment can also provide the same effect as for the above-mentioned first embodiment. 
   According to the description of the above-mentioned first embodiment, the program modules for the client terminal CT ( FIG. 7 ) include the HTTP message program  36  and the communicator program  37 . These program modules can implement the same functions as the communication control section  1032  ( FIG. 13 ) of the client terminal  1002  according to the second embodiment. 
   The content reproduction module  38  ( FIG. 7 ) is a program module capable of implementing the same functions as the encoder/decoder section  1034  ( FIG. 13 ). 
   The copyright protection information management module  39  ( FIG. 7 ) is a program module capable of implementing the same functions as the copyright management section  1035  ( FIG. 13 ). 
   The Internet radio channel selection/reproduction module  43  ( FIG. 7 ) is a program module capable of implementing the same functions as the control section  1023  and the audio control section  1026  ( FIG. 13 ). 
   The musical composition purchase/reproduction module  44  ( FIG. 7 ) is a program module capable of implementing the same functions as the control section  1023  and the audio control section  1026  ( FIG. 13 ). 
   The XML browser  50  ( FIG. 7 ) is a program module capable of implementing the same functions as the input processing section  1021  and the page information generation section  1036  ( FIG. 13 ). 
   The hard disk contents controller  42 , the database access module  40 , and the content data access module  41  ( FIG. 7 ) are program modules capable of implementing the same functions as the control section  1023  ( FIG. 13 ). 
   The authentication library  47 A of the library  47  ( FIG. 7 ) is a program module capable of implementing the same functions as the authentication processing section  1037  and the authentication information storage section  1038  ( FIG. 13 ). 
   The clip library  47 B of the library  47  ( FIG. 7 ) is a program X module capable of implementing the same functions as the control section  1023  ( FIG. 13 ). 
   The associated information display module  45  ( FIG. 7 ) is a program module capable of implementing the same functions as the radio broadcasting display control section  1039  ( FIG. 13 ). 
   The tuner selection/reproduction/recording module  46  ( FIG. 7 ) is a program module capable of implementing the same functions as the control section  1023 , the audio control section  1026 , and the tuner section  1031  ( FIG. 13 ). 
   The audio user interface  51  ( FIG. 7 ) is a program module capable of implementing the same functions as the input processing section  1021 , the control section  1023 , and the display control section  1024  ( FIG. 13 ). 
   The CD reproduction module  48  ( FIG. 7 ) is a program module capable of implementing the same functions as the audio control section  1026  and the external recording media recording and reproducing section  1028  ( FIG. 13 ). 
   The HDD reproduction module  49  ( FIG. 7 ) is a program module capable of implementing the same functions as the control section  1023  and the audio control section  1026  ( FIG. 13 ). 
   That is to say, the client terminal CT has the hardware circuit block configuration according to the first embodiment as mentioned above. Since the CPU  11  uses various program modules, the client terminal CT can implement the same processes as the client terminal  1002  having the functional circuit block configuration according to the second embodiment. 
   The URL provision server  3  ( FIG. 3 ) according to the above-mentioned first embodiment is functionally equivalent to the portal server  1003  ( FIG. 14 ) according to the above-mentioned second embodiment. The control section  80  appropriately selects and follows various programs stored in the ROM  81  to function equivalently to the control section  1050 , the communication control section  1052 , and the authentication processing section  1056  of the portal server  1003 . Further, the ROM  81 , the RAM  82 , and the URL storage DB  83  can be used equivalently to the customer database section  1054 , the page information storage section  1055 , the authentication information storage section  1057 , the frequency information storage section  1058 , and the URL storage section  1059  of the portal server  1003 . 
   Further, the associated information provision server KS ( FIG. 4 ) according to the above-mentioned first embodiment is functionally equivalent to the radio broadcast information delivery server  1006  ( FIG. 15 ) according to the above-mentioned second embodiment. The control section  90  appropriately selects and follows various programs stored in the ROM  91  to function equivalently to the control section  1110 , the communication control section  1112 , the authentication processing section  1115 , and the retrieval section  1118  of the radio broadcast information delivery server  1006 . It is possible to use the ROM  91 , the RAM  92 , the musical composition information DB  93 , and the program information DB  94  in the same manner as the customer database section  1114 , the page information storage section  1116 , the on-air-list information storage section  1117 , the now-on-air information storage section  1119 , and the authentication information storage section  1120  of the radio broadcast information delivery server  1006 . 
   (3) OTHER EMBODIMENTS 
   According to the above-mentioned embodiment, the associated information provision server KS receives a clear instruction to remove the musical composition information from the candidates to be provided the moment that the current program terminates and the next program starts being broadcast. The associated information provision server KS provides the client terminal CT with null musical composition information. However, the present invention is not limited thereto. It may be preferable to provide the client terminal CT with the associated information, e.g., such messages as “The on-air program broadcasts no musical composition yet nor musical composition information to be provided” and allow the client terminal CT to display it. 
   In this case, a user of the client terminal CT can explicitly confirm the broadcasting state of musical compositions in the program instead of displaying nothing on the display  17  of the client terminal CT. 
   According to the above-mentioned embodiment, the associated information provision server KS maintains a database comprising a plurality of pieces of musical composition information and program information. The associated information provision server KS receives notifications to start broadcasting musical composition A or B and a program. The associated information provision server KS reads the musical composition information or the program information stored in the musical composition information database  93  or the program information database  94 . The associated information provision server KS then supplies these pieces of information to the client terminal CT as a broadcast receiver. However, the present invention is not limited thereto. The associated information provision server KS may maintain no data for the musical composition information and the program information, may be supplied with musical composition information and program information from the radio station RS, and may provide these pieces of information to the client terminal CT. 
   According to the above-mentioned embodiment, the radio station RS and the associated information provision server KS are provided independently. However, the present invention is not limited thereto. The radio station RS itself may comprise the associated information provision server KS. The radio station RS may provide associated information to the client terminal CT via the associated information provision server KS. 
   According to the above-mentioned embodiment, the program information associated with the next program is supplied to the client terminal CT until the next program starts broadcasting musical composition B. However, the present invention is not limited thereto. The client terminal CT may be previously supplied with musical composition information associated with musical composition B to be broadcast in the next program. 
   According to the above-mentioned embodiment, the ROM  13  stores the information provision program in advance. The CPU  11  loads this program into the RAM  20 . The client terminal CT follows the information provision program to perform the musical composition information provision sequence or the program information provision sequence mentioned above. However, the present invention is not limited thereto. It may be preferable to perform the musical composition information provision sequence or the program information provision sequence by installing the client terminal CT with a program storage medium that stores the information provision program. 
   According to the above-mentioned first embodiment, the associated information provision server KS functions as the information provision apparatus of the present invention. The associated information provision server KS is configured to comprise the hard disk drive  21  as storage means, the network interface  23  and the communication processing section  22  as request acceptance means and transmission means, and the CPU  11  as update means. However, the present invention is not limited thereto. The other various circuits may be used to configure the information provision apparatus. 
   According to the above-mentioned second embodiment, the radio broadcast information delivery server  1006  functions as the information provision apparatus of the present invention. The radio broadcast information delivery server  1006  is configured to comprise the customer database section  1114 , the now-on-air information storage section  1119 , the on-air-list storage section  1117 , and the page information storage section  1116  as storage means, the communication control section  1112  as request acceptance means and transmission means, and the control section  1110  as update means. However, the present invention is not limited thereto. The other various circuits may be used to configure the information provision apparatus. 
   According to the above-mentioned embodiment, the client terminal  1002  or CT can receive radio broadcast carried from the radio station. However, the present invention is not limited thereto. The client terminal  1002  or CT may receive Internet radio broadcast or satellite radio broadcast to acquire the associated information (radio broadcast information). Alternatively, the client terminal  1002  or CT may receive television broadcast carried from a television broadcast station and acquire various broadcast information and the like about television programs in the television broadcast from a networked server. 
   According to the above-mentioned embodiment, the client terminal  1002  or CT is provided with the hardware circuit blocks, the functional circuit blocks, and the program modules. However, the present invention is not limited thereto. These hardware circuit blocks and the like may be installed in not only the client terminal  1002  or CT, but also the other various terminals such as cellular phones, personal computers, and the like. The same processes as implemented on the above-mentioned client terminal  1002  or CT can be also implemented on terminals installed with the hardware circuit blocks, the functional circuit blocks, and the program modules. 
   INDUSTRIAL APPLICABILITY 
   The information provision method according to the present invention can be applied to the purpose of providing the client terminal with associated information concerning a broadcast program via the network, for example.