Patent Publication Number: US-7720981-B2

Title: Processing device, method for establishing processing device communication session, program, and recording medium

Description:
TECHNICAL FIELD 
   The present invention relates to a processing apparatus that is connectable to a server apparatus for setting an always-on connection session with a device connected through a network, a communication-session establishment method for the processing apparatus, a program, and a storage medium. 
   BACKGROUND ART 
   As methods for accessing from a controlling device on the Internet to a controlled device in a home, a DDNS (dynamic domain name system) and a mail system are available. 
   The DDNS is a scheme in which an in-home controlled device registers its own address with a DDNS server and receives a specified domain name and port number from an internet-side controlling device to allow the access of the controlling device. 
   As a protocol for realizing real-time communication, an XMPP (eXtensible Messaging and Presence Protocol) is available (e.g., refer to “Extensible Messaging and Presence Protocol (XMPP): Core”, RFC3920, The Internet Engineering Task Force (IETF), October 2004). One real-time communication scheme using the XMPP is instant messaging (IM) (e.g., refer to “Extensible Messaging and Presence Protocol (XMPP): Instant Messaging and Presence”, RFC3921, The Internet Engineering Task Force (IETF), October 2004). In the instant messaging (IM), it is checked whether or not an IM client (a friend who can perform IM exchange) is online on the Internet and, when he/she is online, chatting, file exchange, and so on can be performed with the IM client. 
   Also, as a protocol for calling up data or a service existing on another computer, a SOAP (simple object access protocol) is available (e.g., refer to “SOAP Version 1.2”, W3C Recommendation, World Wide Web Consortium (W3C), June 2003). In communications based on the SOAP, messages in which auxiliary information called envelopes are attached to XML (eXtensible Markup Language) documents are exchanged using a protocol such as an HTTP (hyper text protocol). Both a client using a service and a server providing the service have SOAP generation/interpretation engines to allow an object to be called up between different environments. 
   DISCLOSURE OF INVENTION 
   In order to allow a user to access an in-home controlled device from a controlling device over the Internet, a combination of the controlling device and a service type and a controlled device, which is controlled thereby, need to be registered in a linked manner and the registered controlled device needs to be connected in a state that can always accept access. Thus, a demand for a scheme that ensures the operation exists. 
   In view of the foregoing situations, an object of the present invention is to provide a processing apparatus that can simplify a procedure after the completion of device registration until the establishment of an always-on connection session with the server apparatus, a communication-session method for the processing apparatus, a program, and a storage medium. 
   A processing apparatus of the present invention is directed to a processing apparatus that is connectable with a server through a network. The processing apparatus includes storing means for storing information; device registering means for transmitting a registration request for identification information of a self device to the server apparatus and receiving a registration-completion response from the server apparatus; registration recording means for storing, when the device registering means receives the registration-completion response from the server apparatus, registration-completion confirmation information indicating that registration with the server apparatus is completed; and controlling means for establishing a communication session with the server apparatus. When the registration-completion confirmation information is not stored in the storing means, the controlling means establishes the communication session with the server apparatus after the device registering means transmits the registration request to the server apparatus and receives the response therefrom. When the registration-completion confirmation information is stored in the storing means, the controlling means establishes the communication session with the server apparatus without the transmission of the registration request to the server apparatus and the reception of the response therefrom, the transmission and the reception being performed by the device registering means. 
   Once establishing an always-on connection session through, for example, processing for device registration and processing for device authentication with the server apparatus, when the processing apparatus of the present invention turns off the power for the device apparatus and turns on the power again to re-establish a connection, it enters login processing for establishing an always-on connection session without performing processing for device registration and processing for device authentication with the server apparatus. Thus, a controlled device whose registration with the server apparatus has been completed can automatically enter the state of an always-on connection with the server apparatus without performing the processing for the device authentication and the processing for the device registration. 
   The processing apparatus of the present invention further includes identification-information obtaining means for obtaining device-identification information for identifying the self device from the server apparatus and storing the device-identification information in the storing means. Te device registering means transmits a registration request containing the device identification information, stored in the storing means, to the server apparatus. 
   In the processing apparatus of the present invention, the identification-information obtaining means transmits a device-authentication request containing information required for authenticating the self device and obtains the device-identification information. 
   In the processing apparatus of the present invention, the device-identification-information obtaining means obtains the device-identification information and information regarding a validity period of the device-identification information and stores the device identification information and the information regarding the validity period. 
   The processing apparatus according of the present invention further includes registration-completion notifying means for issuing a notification indicating registration completion, upon receiving the registration-completion response from the server apparatus. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a diagram showing an entire configuration of a network system according to one embodiment of the present invention. 
       FIG. 2  is a sequence diagram showing the flow of information in the network system shown in  FIG. 1  during registration of a combination of a controlling device and a service and registration of a controlled device. 
       FIG. 3  is a flow chart showing the operation of the controlling device during the registration shown in  FIG. 2 . 
       FIG. 4  is a flow chart showing the operation of a service server during the registration shown in  FIG. 2 . 
       FIG. 5  is a flow chart showing the operation of a direct-access management server during the registration shown in  FIG. 2 . 
       FIG. 6  is a flow chart showing the operation of a DVR during the registration shown in  FIG. 2 . 
       FIG. 7  is a sequence diagram showing the flow of information in the network system shown in  FIG. 1  during controlled-device XMPP login and remote video-recording reservation. 
       FIG. 8  is a flow chart showing the operation of the mobile phone with respect to remote video-recording reservation. 
       FIG. 9  is a flow chart showing the operation of a service server with respect to the remote video-recording reservation. 
       FIG. 10  is a flow chart showing the operation of the direct-access management server with respect to controlled-device XMPP login, remote video-recording reservation, and content acquirement. 
       FIG. 11  is a flow chart showing the operation of the direct-access management server with respect to the remote video-recording reservation and content acquirement. 
       FIG. 12  is a flow chart showing the operation of a DVR with respect to the remote video-recording reservation and content acquirement. 
       FIG. 13  is a sequence diagram showing the flow of information in the network system shown in  FIG. 1  when the mobile phone directly makes a remote video-recording reservation. 
       FIG. 14  is a sequence diagram showing the flow of information in the network system shown in  FIG. 1  when the mobile phone makes a remote video-recording reservation using tunneling. 
       FIG. 15  is a sequence diagram showing the flow of information in the network system shown in  FIG. 1  when the mobile phone makes direct access to acquire content. 
       FIG. 16  is a sequence diagram showing the flow of information during content acquirement by direct access from the service server. 
       FIG. 17  is a flow chart showing the operation of the mobile phone during the content acquirement. 
       FIG. 18  is a flow chart showing the operation of the service server during the content acquirement. 
       FIG. 19  is a flow chart showing the operation of the service server during the content acquirement. 
       FIG. 20  is a sequence diagram showing the flow of information in the network system shown in  FIG. 1  when the direct access is completed. 
       FIG. 21  is a flow chart showing the operation of the service server when the direct access is completed. 
       FIG. 22  is a flow chart showing the operation of the direct-access management server when the direct access is completed. 
       FIG. 23  is a flow chart showing the operation of the DVR when the direct access is completed. 
       FIG. 24  is a diagram showing a structure of a full JID. 
       FIG. 25  is a diagram showing another structure of the full JID. 
       FIG. 26  is a sequence diagram showing the flow of information when the mobile phone makes a remote video-recording reservation using tunneling without using the service server. 
   

   BEST MODE FOR CARRYING OUT THE INVENTION 
   Embodiments of the present invention will be described below with reference to the drawings. 
     FIG. 1  is a diagram showing an entire configuration of a network system according to one embodiment of the present invention. 
   This network system has a mobile phone  10  serving as a controlling device, a DVR (digital video recorder)  20  serving as a controlled device, a service server  30 , a direct-access management server  40 , and a router  50 . 
   The mobile phone  10  operates as a controlling device for controlling a controlled device. The controlling device may be any device for controlling a controlled device and may be, for example, a PC or PDA (personal digital assistance). 
   The mobile phone  10  includes not only a phone function unit, but also includes, for example, a main memory for storing programs and so on, a CPU (central processing unit) for performing various types of computation processing by executing a program stored in the main memory, an interface unit for a network, an interface unit for the DVR  20 , and a user interface unit such as a key input unit and a display unit, and a nonvolatile storage unit  11 . The storage unit  11  stores user identification information registered in the mobile phone  10 . The main memory stores not only a program for operating the phone function unit, but also includes, for example, a program for performing processing for registering the mobile phone with the service server  30 , making remote video-recording reservation of content, and acquiring content. 
   The DVR  20  includes not only a video-recording/playback function unit for recording/playing back content, such as a broadcast program, to/from a medium, but also includes, for example, a main memory for storing programs and so on, a CPU for performing various types of computation processing by executing a program stored in the main memory, an interface unit for a network, an interface unit for the mobile phone  10 , a nonvolatile storage unit  21 , a remote-control receiver, and an interface unit for connecting a TV or the like. The storage unit  21  pre-stores device authentication information fixedly assigned to the controlled device. The main memory stores not only a program for controlling the video-recording/playback function unit, but also stores, for example, a program for performing processing for registering the controlled device with the direct-access management server  40 , making remote video-recording reservation of content, and acquiring content. Although the DVR  20  has been described as a controlled device in the present embodiment, it may be any device that has a network connection function. For example, it may be a television unit. 
   The service server  30  provides a controlling device, such as the mobile phone  10 , with various services for accessing a controlled device over a network. The service server  30  is realized using, for example, a standard computer system that includes an input unit such as a keyboard/mouse, a display unit, a main memory for storing programs and so on, a CPU for performing various computation processing by executing a program stored in the main memory, a communication unit for a network, and a storage unit  31 . The main memory stores not only a basic program required for operating the computer system but also a program and so on required for executing services. The storage unit  31  stores a service ID for identifying the service server and a service for each service provided by the service server  30 . 
   The direct-access management server  40  manages a controlling device and a relationship between a controlled device and a combination of a controlling device and a service of the service server  30 . The direct-access management server  40  is realized using, for example, a standard computer system that includes an input unit such as a keyboard/mouse, a display unit, a main memory for storing programs and so on, a CPU for performing various computation processing by executing a program stored in the main memory, an interface unit for a network, and a storage unit  41 . The main memory stores not only a basic program required for operating the computer system but also, for example, a program for causing the computer system to function as a direct-access management server. 
   The direct-access management server  40  has a SOAP (Simple Object Access Protocol) server  42  and an XMPP (eXtensible Messaging and Presence Protocol) server  43 . The SOAP server  42  is a server for performing processing, for example, for registering a combination of a controlling device and a service, for registering a controlled device, and for transferring information for directly accessing the service server. The XMPP server  43  is a server for setting a two-way always-on connection session with the DVR  20 , which serves as a controlled device. The SOAP server and the XMPP server are merely examples, and thus, the SOAP server can be replaced with another API-calling-system-based server and the XMPP server can be replaced with another IM-system-based server. 
   Interfaces of the devices will be described next. [IF-**] in  FIG. 1  indicates an interface number. 
   The SOAP server  42  of the direct-access management server  40  has an interface [IF- 02 ] accessed from the service server  30  and interfaces [IF- 00  and IF- 04 ] accessed from the DVR  20 . The SOAP server  42  also has a SOAP client function to access an interface [IF- 05 ] of the service server  30  side. An interface of the XMPP server  43  is accessed from an XMPP client during the establishment of an XMPP session. In this example of the system configuration, the interface corresponds to an interface [IF- 06 ] accessed from the DVR  20 . Since messages can be exchanged in two ways by using the interface [IF- 06 ] after the establishment of an XMPP session, it is also possible for the XMPP server  43  to access an interface [IF- 07 ] of the DVR  20 . The direct-access management server  40  also has an interface [IF- 10 ] of a direct-access URI (uniform resource identifier) provided during XMPP tunneling, described below, with respect to the service server  30 . 
   The service server  30  has an interface [IF- 01 ] accessed from the mobile phone  10  and the interface [IF- 05 ] accessed from the direct-access management server  40 . 
   Although the service server  30  is not directly interfaced with the XMPP server  43  of the direct-access management server  40  in this example of the system configuration, the system may naturally be configured so that the service server  30  is directly interfaced with the XMPP server  43 . 
   The DVR  20  has the interface [IF- 07 ] that is accessed from the direct-access management server  40  after an XMPP session is established, an interface [IF- 03 ] for transmitting/receiving data to/from the mobile phone  10  via, for example, an infrared device or a USB (universal serial bus), and an interface [IF- 09 ] that is accessed from the service server  30  or the mobile phone  10  and that is compatible with a direct-access URI. 
   The router  50  has an interface [IF- 08 ] that is accessed from the DVR  20  and that has a UPnP (Universal Plug and Play) IGD (Internet Gateway Device) function. 
   The operation of the network system of this embodiment will be described next. In the following description, &lt;X-XX&gt; indicates a request and &lt;X-XXR&gt; indicates a response to &lt;X-XX&gt;. 
   [1. Registration of Controlling Device/Service and Controlled Device] 
   First, a description is given of the operation of linking a controlling-device/service management ID issued for each combination of the mobile phone  10  (controlling device) and a service and a controlled-device management ID uniquely issued, in the direct-access management server  40 , to the individual DVR  20  (a controlled device). 
     FIG. 2  is a sequence diagram showing the flow of information during registration of a combination of the mobile phone  10  and a service and registration of the DVR  20 .  FIG. 3  is a flow chart of the mobile phone  10  during the registration.  FIG. 4  is a flow chart of the service server  30  during the registration.  FIG. 5  is a flow chart of the direct-access management server  40  during the registration.  FIG. 6  is a flow chart of the DVR  20  during the registration. 
   [1-1 Registration of Combination of Controlling Device and Service] 
   First, the mobile phone  10  receives a controlled-device registration instruction from a user ( FIG. 3 : step S 301 ). The mobile phone  10  issues a controlled-device registration request &lt;R- 1 &gt; containing the user identification information to the service server  30  ( FIG. 3 : step S 302 ). 
   Upon receiving the controlled-device registration request &lt;R- 1 &gt; containing the user identification information ( FIG. 4 : step S 401 ), the service server  30  determines whether or not a controlling-device/service management ID corresponding to the user identification information is stored in the storage unit  31  ( FIG. 4 : step S 402 ). 
   When a controlling-device/service management ID corresponding to the user identification information is not stored, the service server  30  stores the user identification information in the storage unit  31  ( FIG. 4 : step S 403 ) and issues a controlling-device/service management ID obtaining request &lt;R- 2 &gt; containing a service ID, pre-assigned to the service server  30 , to the SOAP server  42  in the direct-access management server  40  ( FIG. 4 : step S 404 ). The controlling-device/service management ID is uniquely assigned to a combination of a controlling device and each service provided by a service provider. 
   Upon receiving the controlling-device/service management ID obtaining request &lt;R- 2 &gt; ( FIG. 5 : step S 501 ), the SOAP server  42  checks whether or not the service ID contained therein matches a service ID pre-registered in the storage unit  41  of the direct-access management server  40  ( FIG. 5 : step S 502 ). When the service ID does not match, the SOAP server  42  transmits, as a controlling-device/service management ID obtaining response &lt;R- 2 R&gt;, an error code indicating the service ID is not registered to the service server  30  ( FIG. 5 : step S 506 ). When the service ID matches, the SOAP server  42  issues a new controlling-device/service management ID ( FIG. 5 : step S 503 ) and registers a relationship between the controlling-device/service management ID and the service ID in the storage unit  41  ( FIG. 5 : step S 504 ). The SOAP server  42  transmits, as a controlling-device/service management ID obtaining response &lt;R- 2 R&gt;, the controlling-device/service management ID to the service server  30  ( FIG. 5 : step S 505 ). This arrangement allows the direct-access management server  40  to identify the controlling side, viewed from the direct-access management server  40 , by using a combination of the mobile phone  10 , which serves as a controlling device, and a service, which is provided by the service server  30  and used by the mobile phone  10 . 
   Upon receiving the controlling-device/service management ID as the controlling-device/service management ID obtaining response &lt;R- 2 R&gt; ( FIG. 4 : step S 405 ), the service server  30  stores the controlling-device/service management ID in the storage unit  31  in association with the user identification information ( FIG. 4 : step S 406 ). The controlling-device/service management ID is stored in association with the user identification information, as described above. Thus, subsequently, when being accessed from the mobile phone  10 , the service server  30  can issue a request for processing to the to the direct-access management server  40  by using a controlling-device service management ID corresponding to the user identification information of the mobile phone  10  to allow the direct-access management server  40  to uniquely identify a control-request source as the controlling side of a combination of the mobile phone  10 , which serves as a controlling device, and a service of the service server  30 . 
   After the service server  30  registers the controlling-device/service management ID in the storage unit  31  in association with the user identification information or when a controlling-device/service management ID corresponding to the user identification information contained in the controlled-device registration request &lt;R- 1 &gt; received from the mobile phone  10  is registered in the storage unit  31 , the service server  30  issues a controlled-device registration password obtaining request &lt;R- 3 &gt; containing the controlling-device/service management ID and the service ID to the SOAP server  42  in the direct-access management server  40  ( FIG. 4 : step S 407 ). 
   Upon receiving the controlled-device registration password obtaining request &lt;R- 3 &gt; ( FIG. 5 : step S 507 ), the SOAP server  42  in the direct-access management server  40  determines whether or not a combination of the controlling-device/service management ID and the service ID which are contained in the controlled-device registration password obtaining request &lt;R- 3 &gt; is registered in the storage unit  41  ( FIG. 5 : step S 508 ). When the combination is not registered, the SOAP server  42  transmits, as a controlled-device registration password obtaining response &lt;R- 3 R&gt;, an error code indicating that the combination of the controlling-device/service management ID and the service ID is not registered to the service server  30  ( FIG. 5 : step S 512 ). When the combination of the controlling-device/service management ID and the service ID, which are contained in the controlling-device registration password obtaining request &lt;R- 3 &gt; is already registered in the storage unit  41 , the SOAP server  42  generates a controlled-device registration password ( FIG. 5 : step S 509 ) and registers the generated controlled-device registration password and information regarding a validity period specified for the controlled-device registration password in the storage unit  41  in association with the controlling-device/service management ID and the service ID which are contained in the controlled-device registration password obtaining request &lt;R- 3 &gt; ( FIG. 5 : step S 510 ). Thereafter, the SOAP server  42  transmits, as a controlled-device registration password obtaining response &lt;R- 3 R&gt;, the controlled-device registration password and the validity period information of the controlled-device registration password to the service server  30  ( FIG. 5 : step S 511 ). 
   Upon receiving the controlled-device registration password obtaining response &lt;R- 3 R&gt; ( FIG. 4 : step S 408 ), the service server  30  transmits, as a controlled-device registration response &lt;R- 4 &gt;, the controlled-device registration password and the validity period information contained in the controlled-device registration password obtaining response &lt;R- 3 R&gt; to the mobile phone  10  ( FIG. 4 : step S 409 ). 
   Upon receiving the controlled-device registration response &lt;R- 4 &gt; ( FIG. 3 : step S 303 ), the mobile phone  10  stores the controlled-device registration password and the validity period information, which are contained therein, in the storage unit  11  ( FIG. 3 : step S 304 ). 
   Through the processing described above, processing for registering a controlling-device/service management ID with respect to a combination of the mobile phone  10  and a service and processing for issuing a controlled-device registration password used for associating a controlled device with a controlling device are completed. 
   [1-2. Registration of Controlled Device] 
   An operation for registering the DVR  20 , which serves as a controlled device, will be described next. 
   Before use by a user, the DVR  20  authenticates itself with the direct-access management server  40 , as follows. 
   First, the DVR  20  checks the value of an automatic connection flag ( FIG. 6 : step S 601 ). Before the controlled device is registered with the direct-access management server  40 , the value of the automatic connection flag is off. In this case, the DVR  20  transmits a device authentication request &lt;R- 0 &gt; containing pre-set authentication system information and device authentication information to the SOAP server  42  in the direct-access management server  40  ( FIG. 6 : step S 602 ). 
   Upon receiving the device authentication request &lt;R- 0 &gt; from the DVR  20  ( FIG. 5 : step S 513 ), the SOAP server  42  in the direct-access management server  40  determines whether or not the DVR  20  is an authorized device based on the authentication system information and the device authentication information which are contained in the device authentication request &lt;R- 0 &gt; ( FIG. 5 : step S 514 ). When it is determined that the DVR  20  is an unauthorized device, e.g., when the authentication system is different from a predetermined authentication system or when the device authentication information has a format that is different from a predetermined authentication system, the SOAP server  42  transmits, as a device authentication response &lt;R- 0 R&gt;, an error code indicating the failure of the device authentication to the DVR  20  ( FIG. 5 : step S 515 ). When it is determined that the DVR  20  is an authorized device, i.e., when the authentication system matches a predetermined authentication system and the device authentication information has a predetermined authentication system format, the SOAP server  42  generates a device authentication continuation ID to be assigned to the DVR  20  ( FIG. 5 : step S 516 ). The SOAP server  42  then stores the device authentication continuation ID in the storage unit  41  in association with the device authentication information contained in the device authentication request &lt;R- 0 &gt; ( FIG. 5 : step S 517 ). Thereafter, the SOAP server  42  transmits a device authentication response &lt;R- 0 R&gt; containing the generated device authentication continuation ID and its validity period information to the DVR  20  ( FIG. 5 : step S 518 ). The device authentication continuation ID is identification information assigned to a device that has completed its device authentication with the direct-access management server  40 . The identification information allows the direct-access management server  40  to check the device authentication state of the DVR  20 , which serves as a controlled device. 
   Upon receiving the device authentication response &lt;R- 0 R&gt; containing the device authentication continuation ID and the validity period information from the SOAP server  42  in the direct-access management server  40  ( FIG. 6 : step S 603 ), the DVR  20  stores the device authentication continuation ID and the validity period information, which are contained in the device authentication response &lt;R- 0 R&gt;, in the storage unit  21  in association with the device authentication information ( FIG. 6 : step S 604 ). 
   Thereafter, the DVR  20  determines whether or not a controlled-device registration password is registered in the storage unit  21  ( FIG. 6 : step S 605 ). When no controlled-device registration password is stored, the operation is terminated, and when a controlled-device registration password is stored, the process proceeds to step S 609 . Since no controlled-device registration password is stored immediately after the device authentication continuation ID is obtained, the operation is terminated in this case. In the manner described above, the DVR  20 , which serves as a controlled device, stores a combination of the device authentication continuation ID, the validity period information of the device authentication continuation ID, and the device authentication information in the storage unit  21 , and the direct-access management server  40  stores a combination of the device authentication continuation ID and the device authentication information in the storage unit  41 . 
   [1-3. Linking of Controlling-Device/Service Management ID and Controlled-Device Management ID] 
   Next, the operation of associating the controlling-device/service management ID and the controlled-device management ID and registering the associated IDs with the direct-access management server  40  is performed. At the mobile phone  10 , a one-time password transmission request is input from the user ( FIG. 3 : step S 305 ). Upon receiving the one-time password transmission request from the user, the mobile phone  10  uses the interface [IF- 03 ], such as an infrared interface or a USB interface, to transfer, as a one-time password &lt;R- 5 &gt;, the controlled-device registration password stored in the storage unit  11  to the DVR  20 , which serves as a controlled device ( FIG. 3 : step S 306 ). Other possible methods for transferring the controlled-device registration password include various systems, such as transfer via a contactless IC card and wireless transmission using a Bluetooth (trademark), wireless LAN, or the like. Any transfer method, however, may be used as long as the controlled-device registration password can be transferred from the mobile phone  10 , which serves as a controlling device, to the DVR  20 , which serves as a controlled device. Thereafter, the mobile phone  10  deletes the controlled-device registration password from the storage unit  11  ( FIG. 3 : step S 307 ). 
   Upon receiving the controlled-device registration password &lt;R- 5 &gt; from the mobile phone  10  ( FIG. 6 : step S 607 ), the DVR  20  stores the received controlled-device registration password in the storage unit  21  ( FIG. 6 : step S 608 ). Subsequently, the DVR  20  transmits a controlled-device registration request &lt;R- 6 &gt; containing the device authentication continuation ID, stored in the storage unit  21 , and the controlled-device registration password, received from the mobile phone  10 , to the SOAP server  42  in the direct-access management server  40  ( FIG. 6 : step S 609 ). In this manner, the DVR  20  issues, to the direct-access management server  40 , a request for registration in association with the mobile phone  10  that has transmitted the controlled-device registration password. 
   Upon receiving the controlled-device registration request &lt;R- 6 &gt; from the DVR  20  ( FIG. 5 : step S 519 ), the SOAP server  42  in the direct-access management server  40  checks whether or not the device authentication continuation ID contained in the controlled-device registration request &lt;R- 6 &gt; matches what is stored in the storage unit  41  and also checks the validity period of the device authentication continuation ID ( FIG. 5 : step S 520 ). When it is determined to be NG in the checking operations, i.e., when the device authentication continuation ID does not match or when the validity period of the device authentication continuation ID has expired, the SOAP server  42  transmits a controlled-device registration response &lt;R- 6 R&gt; containing an error code indicating the requirement of device authentication to the DVR  20  ( FIG. 5 : step S 528 ). When the DVR  20  receives the controlled-device registration response &lt;R- 6 R&gt; containing the error code ( FIG. 6 : step S 622 ), the process returns to step S 602  and the processing for the device authentication is repeated. 
   When the result of the checking in step S 520  is OK, i.e., when the device authentication continuation ID matches what is stored in the storage unit  41  and the validity period of the device authentication continuation ID has not expired, the SOAP server  42  checks whether or not the controlled-device registration password contained in the controlled-device registration request &lt;R- 6 &gt; received from the DVR  20  matches what is stored in the storage unit  41  and also checks the validity period of the controlled-device registration password ( FIG. 5 : step S 521 ). When it is determined to be NG in the checking operations, i.e., when the controlled-device registration password does not match or when the validity period of the controlled-device registration password has expired, the SOAP server  42  transmits, as a controlled-device registration response &lt;R- 6 R&gt;, an error code indicating that the controlled-device registration password contained in the controlled-device registration request &lt;R- 6 &gt; is invalid to the DVR  20  ( FIG. 5 : step S 527 ). Upon receiving the error code as the controlled-device registration response &lt;R- 6 R&gt; ( FIG. 6 : step S 620 ), the DVR  20  displays an error message to the user ( FIG. 6 : step S 621 ) through a TV screen or the like, which is connected to the DVR  20 , so that a controlled-device registration password is to be obtained again, and the finishes the processing. 
   When the result of the checking in step S 521  is OK, i.e., when the controlled-device registration password matches what is stored in the storage unit  41  and the validity period of the controlled-device registration password has not expired, the SOAP server  42  refers to information stored in the storage unit  41  to determine whether or not a controlled-device management ID is assigned to the device authentication continuation ID contained in the controlled-device registration request &lt;R- 6 &gt; ( FIG. 5 : step S 521 - 1 ). When a controlled-device management ID corresponding to the device authentication continuation ID has not been assigned yet, the SOAP server  42  assigns a controlled-device management ID to the DVR  20  ( FIG. 5 : step S 522 ) and stores the assigned controlled-device management ID in the storage unit  41  in association with the device authentication information and the device authentication continuation ID of the DVR  20  ( FIG. 5 : step S 523 ). When a controlled-device management ID has already been assigned to the device authentication continuation ID contained in the controlled-device registration request &lt;R- 6 &gt;, the SOAP server  42  stores the controlled-device management ID in the storage unit  41  in association with the controlling-device/service management ID that is stored in the storage unit  41  in association with the controlled-device registration password ( FIG. 5 : step S 523 - 1 ). The controlled-device management ID in this case refers to identification information uniquely assigned, in the direct-access management server  40 , to a controlled device. In the manner described above, the controlling-device/service management ID assigned to a combination of the controlling device and a service and the controlled-device management ID assigned to the controlled device are linked. In this linking, multiple controlled-device management IDs may be linked to one controlling-device/service management ID or, conversely, multiple controlling-device/service management IDs may be linked to one controlled-device management ID. 
   Next, the SOAP server  42  transmits, as a controlled-device registration response &lt;R- 6 R&gt;, the number of services whose linking operations are already completed to the DVR  20  ( FIG. 5 : step S 524 ). Next, the SOAP server  42  transmits, to the service server  30 , a controlled-device registration completion notification &lt;R- 7 &gt; containing the service ID, the controlling-device/service management ID, and the controlled-device registration password which are stored in the storage unit  41  ( FIG. 5 : step S 525 ). Thereafter, the SOAP server  42  deletes the controlled-device registration password in the storage unit  41  ( FIG. 5 : step S 526 ) and finishes the processing. Upon receiving the controlled-device registration completion notification &lt;R- 7 &gt; from the SOAP server  42  ( FIG. 4 : step S 410 ), the service server  30  issues a notification indicating that the controlled-device registration is completed to the mobile phone  10  ( FIG. 4 : step S 411 ). Examples of a method for causing the service server  30  to issue the notification indicating the completion of the controlled-device registration to the mobile phone  10  include electronic mail and an application prepared for communicating with the mobile phone  10  by using another method. 
   Upon receiving, as the controlled-device registration response &lt;R- 6 R&gt;, the number of services whose linking operations are already completed from the SOAP server  42  ( FIG. 6 : step S 610 ), the DVR  20  turns on an automatic connection flag ( FIG. 6 : step S 611 ) and displays a message indicating that the controlled-device registration has been completed ( FIG. 6 : step S 612 ). Subsequently, the DVR  20  deletes the controlled-device registration password stored in the storage unit  21  ( FIG. 6 : step S 613 ). Thereafter, in order to establish an always-on connection session with the XMPP server  43  of the direct-access management server  40 , the DVR  20  transmits an XMPP login information obtaining request &lt;D- 0 - 1 &gt; containing the device authentication continuation ID to the SOAP server  42  in the direct-access management server  40  ( FIG. 6 : step S 614 ). 
   [2. XMPP Login of Controlled Device] 
   In this network system, the direct-access management server  40  has the XMPP server  43  for establishing a two-way always-on connection session with a controlled device. In order for the mobile phone  10 , which serves as a controlling device, to access the DVR  20 , which serves as a controlled device, through a network, the DVR  20  logs in on the XMPP server  43  in advance to establish an always-on connection session with the XMPP server  43 . Thus, the service server  30  and the mobile phone  10  can obtain necessary information from the DVR  20 , when required. In order to simplify the design of the service server  30  in this case, an XMPP protocol is incorporated into the direct-access management server  40  and the DVR  20  so that only the use of a SOAP interface allows information to be exchanged with the XMPP server  43  that establishes a two-way always-on connection session with the DVR  20 . 
   A part of  FIG. 7  is a sequence diagram showing the flow of information related to XMPP login of a controlled device, and a part of  FIG. 10  is a flow chart showing the operation of the direct-access management server  40  with respect to the XMPP login of the controlled device. 
   As shown in these figures, upon receiving the XMPP login information obtaining request &lt;D- 0 - 1 &gt; containing the device authentication continuation ID from the DVR  20  ( FIG. 10 : step S 1001 ), the direct-access management server  40  checks the device authentication continuation ID and the device-authentication-continuation-ID validity period which are contained in the XMPP login information obtaining request &lt;D- 0 - 1 &gt; ( FIG. 10 : step S 1002 ). In this checking, when the device authentication continuation ID contained in the XMPP login information obtaining request &lt;D- 0 - 1 &gt; does not match what is stored in the storage unit  41  of the direct-access management server  40  or when the validity period has expired, this means that the DVR  20  is not properly registered with the direct-access management server  40  or the DVR  20  was registered in the past but the validity period of the device authentication continuation ID during the registration has expired. Thus, the direct-access management server  40  transmits, as an XMPP login information obtaining response &lt;D-O- 1 R&gt;, an error code indicating that device authentication is required to the DVR  20  ( FIG. 10 : step S 1003 ). When the device authentication continuation ID is stored in the storage unit  41  and the validity period of the device authentication continuation ID has not expired, the direct-access management server  40  searches the storage unit  41  for a controlled-device management ID and device authentication information which are linked with the device authentication continuation ID ( FIG. 10 : step S 1004 ). Based on the controlled-device management ID and the device authentication information, the DVR  20  generates a full JID(D) that is an XMPP login ID required for logging in on the XMPP server  43 , an XMPP login password, and the validity period information of the XMPP login password ( FIG. 10 : step S 1005 ) and stores those pieces of information in the storage unit  41  ( FIG. 10 : step S 1006 ). The direct-access management server  40  transmits, as an XMPP login information obtaining response &lt;D- 0 - 1 R&gt;, the generated full JID(D), the XMPP login password, and the validity period information, together with information of an XMPP address, a port number, authentication system information, and an SSL (secure socket layer) option, to the DVR  20  ( FIG. 10 : step S 1007 ). 
   Upon receiving the XMPP login information obtaining response &lt;D- 0 - 1 R&gt; containing the full JID(D), the XMPP login password, and so on from the SOAP server  42  in the direct-access management server  40  ( FIG. 6 : step S 615 ), the DVR  20  transmits an XMPP login authentication request &lt;D- 0 - 2 &gt; containing the full JID(D) and the XMPP login password to the XMPP server  43  in the direct-access management server  40  ( FIG. 6 : step S 616 ). 
   Upon receiving the XMPP login authentication request &lt;D- 0 - 2 &gt; from the DVR  20  ( FIG. 10 : step S 1008 ), the XMPP server  43  in the direct-access management server  40  checks the full JID(D), the XMPP login password, and the XMPP-login-password validity period which are contained in the XMPP login authentication request &lt;D- 0 - 2 &gt; ( FIG. 10 : step S 1009 ). When the full JID(D) does not match what is stored in the storage unit  41 , when the XMPP login password does not match what is stored in the storage unit  41 , or when the XMPP-login-password validity period has expired, the XMPP server  43  transmits, as an XMPP login authentication response &lt;D- 0 - 2 R&gt;, an error code indicating the failure of the XMPP login to the DVR  20  ( FIG. 10 : step S 1010 ). When all of the checking operations of the full JID(D), the XMPP login password, and the validity period are OK, the XMPP server  43  in the direct-access management server  40  transmits, as an XMPP login authentication response &lt;D- 0 - 2 R&gt;, a code indicating the permission of the XMPP login to the DVR  20  ( FIG. 10 : step S 1011 ). 
   When the DVR  20  receives, as the XMPP login authentication response &lt;D- 0 - 2 R&gt;, the error code indicating the failure of the XMPP login from the direct-access management server  40  ( FIG. 6 : step S 619 ), the process returns to S 614  and the DVR  20  re-issues a request for obtaining XMPP login information. That is, since there is a possibility that the validity period of the XMPP login password has expired, the DVR  20  performs processing for issuing a request for obtaining XMPP login information again. Upon receiving, as the XMPP login authentication response &lt;D- 0 - 2 R&gt;, the code indicating the permission of the XMPP login from the direct-access management server  40  ( FIG. 6 : step S 618 ), the DVR  20  completes the XMPP login processing. 
   When the DVR  20  receives, as the XMPP login information obtaining response &lt;D- 0 - 1 R&gt;, the error code indicating the device authentication is required from the SOAP server  42  in the direct-access management server  40  ( FIG. 6 : step S 617 ), there is a possibility that the DVR  20  is not properly stored in the direct-access management server  40  or the validity period of the device authentication continuation ID has expired. Thus, the DVR  20  re-transmits the device authentication request &lt;R- 0 &gt; containing the device authentication information and authentication system information preset in the DVR  20  to the SOAP server  42  in the direct-access management server  40  to redo the device authentication of the DVR  20  ( FIG. 6 : step S 602 ). 
   As described above, in this network system, the direct-access management server  40  generates the XMPP login ID (full JID(D)) and the XMPP login password which are required for the DVR  20  to log in on the XMPP server  43  and transmits the generated ID and password to the DVR  20 . For example, as shown in  FIG. 24 , the full JID(D) is constituted by a bare JID portion and a resource portion. The controlled-device management ID assigned to the controlled device is used for the bare JID portion and a product code and a serial number obtained from the device authentication information are used for the resource portion. As shown in  FIG. 25 , the controlling-device/service management ID for identifying a combination of a controlling device and a service may be used for the resource portion. 
   With the automatic connection flag being turned on in step S 611 , when the DVR  20  is connected next time, for example, when the DVR  20  is powered off and then powered on or when the DVR  20  disconnects a session with the XMPP server  43  and then re-establishes the connection, the DVR  20  checks the automatic connection flag in step S 601  and then starts processing from the transmission of the XMPP login information obtaining request &lt;D- 0 - 1 &gt; in step S 614 . That is, during the re-connection, the DVR  20  skips processing for device authentication, processing for obtaining a controlled-device registration password from the mobile phone  10 , and processing for controlled-device registration, and enters processing for XMPP login. Thus, during re-connection, the DVR  20  can establish a connection session with the XMPP server  43  by only performing processing for XMPP login. 
   Through the processing described above, processing for associating the DVR  20 , which serves as a controlled device, as a target to be controlled by the mobile phone  10 , which servers as a controlling device, is completed. Specific processing between two associated devices, i.e., processing in which the mobile phone  10  controls the DVR  20 , will be described below. 
   [3. Remote Video-Recording Reservation] 
   The operation of performing remote video-recording reservation on the DVR  20  will be described. 
   A part of  FIG. 7  is a sequence diagram showing the flow of information during remote video-recording reservation.  FIG. 8  is a flow chart showing the operation of the mobile phone  10  with respect to the remote video-recording reservation.  FIG. 9  is a flow chart showing the operation of the service server  30  with respect to the remote video-recording reservation.  FIGS. 10 and 11  are flow charts showing the operation of the direct-access management server  40  with respect to the remote video-recording reservation and content acquirement.  FIG. 12  is a flow chart showing the operation of the DVR  20  with respect to the remote video-recording reservation and the content acquirement. 
   When the user of the mobile phone  10  gives a direct-access use start instruction to the mobile phone  10  in order to receive a remote video-recording reservation service (FIG.  8 : step S 801 ), the mobile phone  10  transmits a controlled-device-list obtaining request &lt;D- 1 &gt; containing the user identification information preset in the mobile phone  10  to the service server  30  ( FIG. 8 : step S 802 ). 
   Upon receiving the controlled-device-list obtaining request &lt;D- 1 &gt; from the mobile phone  10  ( FIG. 9 : step S 901 ), the service server  30  determines whether or not a controlling-device/service management ID corresponding to the user identification information contained in the controlled-device-list obtaining request &lt;D- 1 &gt; is stored in the storage unit  31  ( FIG. 9 : step S 902 ). When a controlling-device/service management ID corresponding to the user identification information is not stored in the storage unit  31 , the service server  30  transmits, as a controlled-device-list obtaining response &lt;D- 3 &gt;, an error code indicating that controlled-device registration is required to the mobile phone  10  ( FIG. 9 : step S 903 ). When a controlling-device/service management ID corresponding to the user identification information is stored in the storage unit  31 , the service server  30  transmits a controlled-device-list obtaining request &lt;D- 2 &gt; containing the controlling-device/service management ID and a service ID, which is information for identifying a service, to the direct-access management server  40  ( FIG. 9 : step S 904 ) in order to obtain a list of controlled devices associated with the controlling-device/service management ID managed by the direct-access management server  40 . 
   Upon receiving the controlled-device-list obtaining request &lt;D- 2 &gt; from the service server  30  ( FIG. 10 : step S 1012 ), the direct-access management server  40  determines whether or not a combination of the service ID and the controlling-device/service management ID which are contained in the controlled-device-list obtaining request &lt;D- 2 &gt; is stored in the storage unit  41  ( FIG. 10 : step S 1013 ). If the combination is not stored, the direct-access management server  40  transmits, as a controlled-device-list obtaining response &lt;D- 2 R&gt;, an error code indicating the combination is not registered to the service server  30  ( FIG. 10 : step S 1014 ). Upon receiving, as the controlled-device-list obtaining response &lt;D- 2 R&gt;, the error code indicating the combination is not registered from the direct-access management server  40  ( FIG. 9 : step S 905 ), the service server  30  transmits, as a controlled-device-list obtaining response &lt;D- 3 &gt;, an error code indicating that controlled-device registration is required to the mobile phone  10  ( FIG. 9 : step S 906 ). When the mobile phone  10  receives, as the controlled-device-list obtaining response &lt;D- 3 &gt;, the error code from the service server  30  ( FIG. 8 : step S 803 ), it displays an error message indicating that the registration of a controlled device for the service is required to the user via the display unit ( FIG. 8 : step S 804 ). 
   When it is determined in step S 1013  that the combination of the service ID and the controlling-device/service management ID contained in the controlled-device-list obtaining request &lt;D- 2 &gt; is stored in the storage unit  41 , the direct-access management server  40  generates, as a controlled-device list, a list containing numbers re-assigned for the controlled-device management IDs of controlled devices controllable by the mobile phone  10 , device names contained in the device authentication information of the controlled devices, and so on in accordance with the linking contents of the controlling-device/service management ID and the controlled-device management ID which are stored in the storage unit  41 . The direct-access management server  40  then stores the controlled-device list in the storage unit  41  in association with controlling-device/service management ID and transmits a controlled-device-list obtaining response &lt;D- 2 R&gt; containing the controlled-device list to the service server  30  ( FIG. 10 : step S 1015 ). When the service server  30  receives the controlled-device-list obtaining response &lt;D- 2 R&gt; containing the controlled-device list from the direct-access management server  40  ( FIG. 9 : step S 907 ), it transmits a controlled-device-list obtaining response &lt;D- 3 &gt; containing the controlled-device list to the mobile phone  10  ( FIG. 9 : step S 908 ). 
   When the mobile phone  10  receives the controlled-device-list obtaining response &lt;D- 3 &gt; containing the controlled-device list ( FIG. 8 : step S 805 ), it determines whether or not multiple controlled-device numbers exist in the controlled-device list ( FIG. 8 : step S 806 ). When multiple controlled-device numbers exist, the mobile phone  10  displays the contents of the controlled-device list on the display unit ( FIG. 8 : step S 807 ), prompts the user to select one of the controlled-device numbers ( FIG. 8 : step S 808 ), and stores the selected controlled-device number in the storage unit  11  ( FIG. 8 : steps S 809  and S 811 ). When multiple controlled devices do not exist, the number of the one controlled device is stored in the storage unit  11  ( FIG. 8 : steps S 810  and S 811 ). 
   Next, the mobile phone  10  branches the process, depending on whether or not a service to be used (i.e., remote video-recording reservation) is a service that is directly accessible from the mobile phone  10  to the controlled device ( FIG. 8 : step S 812 ). When the mobile phone  10  is to use a service that is directly accessible, the mobile phone  10  transmits a new remote video-recording reservation request &lt;D- 4 &gt; containing the user identification information, the controlled-device number, and the mobile-device direct flag (on) which are stored in the storage unit  11  to the service server  30  ( FIG. 8 : step S 813 ). When a service that is directly accessible from the mobile phone  10  is to be used, the value of the mobile-device direct flag is set to be on, and when a service that is not directly accessible from the mobile phone  10  is used, the value of the mobile-device direct flag is set to be off. Thus, when the mobile phone  10  is to use a service that is not directly accessible, the mobile phone  10  transmits a new remote video-recording reservation request &lt;D- 4 &gt; containing the user identification information, video-recording reservation program information, the controlled-device number, and the mobile-device direct flag (off) to the service server  30  ( FIG. 8 : step S 814 ). The video-recording reservation program information is constituted by, for example, video-recording start time, the length of a program, a broadcast type, a channel, a forced reservation flag, and so on. 
   Upon receiving the new remote video-recording reservation request &lt;D- 4 &gt; from the mobile phone  10  ( FIG. 9 : step S 909 ), the service server  30  checks whether or not an available XMPP session ID, i.e., an ID for identifying a connection session established with the XMPP server  43 , is stored in the storage unit  31  in association with the user identification information of the mobile phone  10  ( FIG. 9 : step S 910 ), the user identification information being contained in the new remote video-recording reservation request &lt;D- 4 &gt;. When an available XMPP session ID is not stored, the service server  30  transmits an XMPP login request &lt;D- 5 &gt; containing the service ID, the controlling-device/service management ID, and the controlled-device number to the direct-access management server  40  ( FIG. 9 : step S 912 ) in order to establish an XMPP session with the XMPP server  43 . 
   Upon receiving the XMPP login request &lt;D- 5 &gt; from the service server  30  ( FIG. 10 : step S 1016 ), the direct-access management server  40  determines whether or not a combination of the service ID, the controlling-device/service management ID, and the controlled-device number which are contained in the XMPP login request &lt;D- 5 &gt; is stored in the storage unit  41  ( FIG. 10 : step S 1017 ). When the combination is not stored, the direct-access management server  40  transmits, as an XMPP login response &lt;D- 5 R&gt;, an error code indicating that a controlled device for the corresponding service does not exist to the service server  30  ( FIG. 10 : step S 1018 ). Thereafter, the operation of the direct-access management server  40  ends. When a controlled device for the corresponding service is stored in the storage unit  41 , the direct-access management server  40  generates an XMPP session ID and stores the generated XMPP session ID in the storage unit  41  in association with the service ID, the controlling device/service management ID, and the controlled-device number ( FIG. 10 : step S 1019 ). The direct-access management server  40  then transmits an XMPP login response &lt;D- 5 R&gt; containing the XMPP session ID to the service server  30  ( FIG. 10 : step S 1020 ) 
   Upon receiving the XMPP login response &lt;D- 5 R&gt; containing the XMPP session ID from the direct-access management server  40  ( FIG. 9 : step S 913 ), the service server  30  stores the XMPP session ID contained in the XMPP login response &lt;D- 5 R&gt; and the value of the mobile-device direct flag contained in the new remote video-recording reservation request &lt;D- 4 &gt; issued in step S 909  in the storage unit  31  in association with the service ID, the controlling-device/service management ID, and the controlled-device list number ( FIG. 9 : step S 914 ). 
   On the other hand, when the result of the determination performed by the service server  30  in step S 910  indicates that an available XMPP session ID is already stored in the storage unit  31 , the service server  30  stores the value of the mobile-device direct flag contained in the new remote video-recording reservation request &lt;D- 4 &gt; in the storage unit  31  in association with the service ID, the controlling-device/service management ID, and the controlled-device number ( FIG. 9 : step S 911 ). 
   After the mobile-device direct flag is stored in step S 911  or step S 914 , the service server  30  transmits a direct-access start request &lt;D- 6 &gt; containing the service ID, the controlling-device/service management ID, a service URN (uniform resource name), and the XMPP session ID to the direct-access management server  40  ( FIG. 9 : step S 915 ). The service URN in this case is information for specifying one of services (applications) that can be provided by a controlled device. In this case, since the mobile phone  10  is to perform remote video-recording reservation on the DVR  20 , the service URN is information specifying a remote video-recording reservation service. 
   Upon receiving the direct-access start request &lt;D- 6 &gt; from the service server  30  ( FIG. 11 : step S 1101 ), the direct-access management server  40  determines whether or not a combination of the service ID and the controlling-device/service management ID which are contained in the direct-access start request &lt;D- 6 &gt; is stored in the storage unit  41  ( FIG. 11 : step S 1102 ). When the combination is not stored, the direct-access management server  40  transmits, as a direct-access start response &lt;D- 10 &gt;, an error code indicating that controlled-device registration is required to the service server  30  ( FIG. 11 : step S 1103 ). When the combination of the service ID and the controlling-device/service management ID contained in the direct-access start request &lt;D- 6 &gt; is stored in the storage unit  41 , the direct-access management server  40  determines whether or not the XMPP session ID contained in the direct-access start request &lt;D- 6 &gt; is stored in the storage unit  41  in association with the combination of the service ID and the controlling-device/service management ID contained in the direct-access start request &lt;D- 6 &gt; ( FIG. 11 : step S 1104 ). When the XMPP session ID is not stored, the direct-access management server  40  transmits, as a direct-access start response &lt;D- 10 &gt;, an error code indicating that the XMPP session ID is invalid to the service server  30  ( FIG. 11 : step S 1105 ). When the service server  30  receives, as the direct-access start response &lt;D- 10 &gt;, the error code indicating that the XMPP session ID is invalid from the direct-access management server  40  ( FIG. 9 : step S 916 ), the process returns to step S 912  and the service server  30  transmits an XMPP login request &lt;D- 5 &gt; to the direct-access management server  40  to re-establish an XMPP session. 
   When it is determined in step S 1104  that the XMPP session ID contained in the direct-access start request &lt;D- 6 &gt; is stored in the storage unit  41  in association with the combination of the service ID and the controlling-device/service management ID contained in the direct-access start request &lt;D- 6 &gt;, the direct-access management server  40  transmits a direct-access URI obtaining request &lt;D- 7 &gt; to the DVR  20 , which serves as a controlled device, through the always-on connection session established between the XMPP server  43  and the DVR  20  ( FIG. 11 : step S 1106 ). The direct-access URI obtaining request &lt;D- 7 &gt; contains designation information of the service URN specified by the direct-access start request &lt;D- 6 &gt;, the service URN being information for identifying the service. 
   Upon receiving the direct-access URI obtaining request &lt;D- 7 &gt; containing the designation information of the service URN from the direct-access management server  40  ( FIG. 12 : step S 1201 ), the DVR  20  assigns a direct-access local port ( FIG. 12 : step S 1202 ). Next, the DVR  20  transmits, to the router  50 , a NAT (network address translation) setting request &lt;D- 8 &gt; for a direct-access port. The NAT setting request &lt;D- 8 &gt; contains a local IP address pre-assigned to the DVR  20  and the port number of the direct-access local port. The DVR  20  then issues, to the router  50 , a request for mapping a port number and a global IP address accessible from the Internet to the port number and the local IP address ( FIG. 12 : step S 1203 ). For example, in order to assign a direct-access URI, the DVR  20  accesses the router  50  based on a UPnP IGD DCP (device control protocol) or the like to pre-obtain a port number and an global IP address accessible from the Internet. 
   When the DVR  20  receives, as a NAT setting response &lt;D- 8 R&gt;, a global IP address and a port number associated with the local IP address and the port number of the DVR  20  from the router  50  ( FIG. 12 : step S 1208 ) in response to the direct-access-port NAT setting request &lt;D- 8 &gt; transmitted in step S 1203 , the DVR  20  uses the global IP address and the port number to create a direct-access URI list and transmits, as a direct-access URI obtaining response &lt;D- 9 &gt;, the direct-access URI list to the direct-access management server  40  ( FIG. 12 : step S 1209 ). The direct-access URI list refers to a URI list for directly accessing from the service server  30  or the mobile phone  10  to a corresponding device through the network. 
   Upon receiving the direct-access URI list as the direct-access URI obtaining response &lt;D- 9 &gt; ( FIG. 11 : step S 1107 ), the XMPP server  43  of the direct-access management server  40  transmits, as a direct-access start response &lt;D- 10 &gt;, the direct-access URI list to the service server  30  ( FIG. 11 : step S 1111 ). 
   When the DVR  20  receives, as a direct-access port NAT setting response &lt;D- 8 R&gt;, a global-IP-address and port-number obtaining error from the router  50  ( FIG. 12 : step S 1204 ), the DVR  20  determines whether or not the service URN can be tunneled ( FIG. 12 : step S 1205 ) based on the service-URN designation information obtained in step S 1201 . In this case, specific services of services provided are pre-determined as services that can be tunneled. For example, a service having a relatively small amount of data to be communicated, such as a remote video-recording service, is determined as a service that can be tunneled, and a service having a relatively large amount of data to be communicated, such as a content acquiring service, is determined as a service that cannot be tunneled. Thus, when it is determined that the service-URN designation information contained in the direct-access URI obtaining request &lt;D- 7 &gt; indicates a new remote video-recording reservation, the DVR  20  transmits, as a direct-access URI obtaining response &lt;D- 9 &gt;, an error code that gives an instruction for tunneling to the direct-access management server  40  ( FIG. 12 : step S 1206 ). The tunneling designation is performed by, for example, filling all address portions of a direct-access URI with “0s”. 
   When the XMPP server  43  of the direct-access management server  40  receives, as the direct-access URI obtaining response &lt;D- 9 &gt;, the error code that gives an instruction for tunneling ( FIG. 11 : step S 1109 ), the XMPP server  43  assigns a tunneling port in the direct-access management server  40  ( FIG. 11 : step S 1110 ), uses the port number of the assigned tunneling port in the direct-access management server  40  and the global IP address of the direct-access management server  40  to create a direct-access URI list, and transmits a direct-access start response &lt;D- 10 &gt; containing the direct-access URI list to the service server  30  ( FIG. 11 : step S 1111 ). With this arrangement, the service server  30  and the mobile phone  10  can access the DVR  20  without being aware of the tunneling. 
   When it is determined in step S 1205  that the service-URN designation information contained in the direct-access URI obtaining request &lt;D- 7 &gt; indicates a service URN that can be tunneled, the DVR  20  transmits, as a direct-access URI obtaining response &lt;D- 9 &gt;, an error code indicating the failure of acquiring an available port to the direct-access management server  40  ( FIG. 12 : step S 1207 ). 
   Upon receiving the direct-access start response &lt;D- 10 &gt; containing the direct-access URI list from the direct-access management server  40  ( FIG. 9 : step S 917 ), the service server  30  determines whether the mobile-device direct flag is on or off ( FIG. 19 : step S 918 ). When the mobile-device direct flag is on, the service server  30  transmits a new remote video-recording reservation response &lt;D- 13 &gt; containing a direct-access URI to the mobile phone  10  ( FIG. 9 : step S 919 ) in order to allow the mobile phone  10  to directly access a device specified by the direct-access URI. When the mobile-device direct flag is off, the service server  30  transmits a new remote video-recording reservation request containing the direct-access URI and the video-recording reservation program information, obtained from the new remote video-recording reservation request &lt;D- 4 &gt; transmitted from the mobile phone  10 , to the direct-access URI ( FIG. 9 : step S 920 ). 
   Some specific examples in which the mobile phone  10  issues a video-recording reservation request to the DVR  20  will be described below. 
   [3-1. Remote Video-Recording Reservation Using Proxy Access by Service Server  30 :  FIG. 7  ] 
   A description will be given of the operation of a case in which the service server  30  receives an instruction from the mobile phone  10  to perform remote video-recording reservation on the DVR  20  by proxy. A part of  FIG. 7  is a sequence diagram showing the flow of information when the service server  30  that has received an instruction from the mobile phone  10  performs remote video-recording reservation on the DVR  20  by proxy. 
   In the flow of information between the mobile phone  10 , the DVR  20 , the service server  30 , the direct-access management server  40 , and the router  50 , the processing of each device until the direct-access start response &lt;D- 10 &gt; is the same as the processing described above. 
   A case in which the service server  30  that has received an instruction from the mobile phone  10  performs remote video-recording reservation on the DVR  20  by proxy corresponds to a case in which it is determined in step S 918  that the mobile-device direct flag is off and the URI transmitted, as the direct-access URI obtaining request &lt;D- 9 &gt;, from the DVR  20  in step S 1209  is contained in the direct-access start response &lt;D- 10 &gt; received by the service server  30  in step S 917 . Since the service server  30  merely needs to access the direct-access URI received as the direct-access start response &lt;D- 10 &gt;, as described above, it is not particularly necessary to determine whether the direct-access URI corresponds to the DVR  20  or the tunneling of the direct-access management server  40 . 
   The service server  30  accesses the address of the DVR  20 , the address being included in the direct-access URI received in step S 917  as the direct-access start response &lt;D- 10 &gt;, and transmits a new remote video-recording reservation request &lt;D- 11 &gt; containing the video-recording reservation program information obtained from the new remote video-recording reservation request &lt;D- 4 &gt; transmitted from the mobile phone  10  ( FIG. 9 : step S 920 ). 
   Upon receiving the new remote video-recording reservation request &lt;D- 11 &gt; from the service server  30  ( FIG. 12 : step S 1210 ), the DVR  20  checks the validity of the direct-access URI contained in the new remote video-recording reservation request &lt;D- 11 &gt; ( FIG. 12 : step S 1211 ). When the direct-access URI is invalid, the DVR  20  transmits, as a new remote video-recording reservation response &lt;D- 11 R&gt;, an error code indicating so to the service server  30  (FIG.  12 : step S 1212 ). Examples of a method for checking the validity of the direct-access URI include a method in which a random number that cannot be easily reproduced is added during the issuance of the direct-access URI and it is checked whether or not the random number is included in the direct-access URI in the new remote video-recording reservation request &lt;D- 11 &gt;. When the direct-access URI is valid, the DVR  20  determines whether or not the video-recording date and time of a video-recording reservation requested by the service server  30  overlaps the video-recording data and time of an already scheduled video-recording reservation, based on the video-recording reservation program information. When there is no overlapping video-recording reservation, the DVR  20  makes a video-recording reservation based on the video-recording reservation program information and creates a reservation overlapping program list indicating that there is no reservation overlapping. When an overlapping video-recording reservation is found, the DVR  20  creates a reservation overlapping program list that contains video-recording date and time, a channel, a program title, and so on of the overlapping video-recording reservation. Thereafter, the DVR  20  transmits a new remote video-recording reservation response &lt;D- 11 R&gt; containing the reservation overlapping program list to the service server  30  ( FIG. 12 : step S 1213 ). 
   Upon receiving the new remote video-recording reservation response &lt;D- 11 R&gt; ( FIG. 9 : step S 921 ), the service server  30  transmits, as a new remote video-recording reservation response &lt;D- 12 &gt;, the reservation overlapping program list in the new remote video-recording reservation response &lt;D- 11 R&gt; to the mobile phone  10  ( FIG. 9 : step S 922 ). When the service server  30  receives the invalid-URI error code as the new remote video-recording reservation response &lt;D- 11 R&gt; ( FIG. 9 : step S 923 ), the service server  30  transmits, as a new remote video-recording reservation response &lt;D- 12 &gt;, the error code to the mobile phone  10  ( FIG. 9 : step S 924 ). 
   When the mobile phone  10  receives the new remote video-recording reservation response &lt;D- 12 &gt; containing the reservation overlapping program list from the service server  30  ( FIG. 8 : step S 823 ), the mobile phone  10  determines whether or not a reservation overlapping program exists based on the reservation overlapping program list ( FIG. 8 : step S 824 ). When a reservation overlapping program exists, the mobile phone  10  displays the information of the reservation overlapping program to the user via the display unit ( FIG. 8 : step S 825 ). When no reservation overlapping program exists, the mobile phone  10  displays a message indicating the success of the remote video-recording reservation to the user via the display unit ( FIG. 8 : step S 826 ). 
   When the mobile phone  10  receives, as the new remote video-recording reservation response &lt;D- 12 &gt;, the invalid-URI error code from the service server  30  ( FIG. 8 : step S 827 ), the mobile phone  10  displays an error message indicating the failure of the direct access to the user via the display unit ( FIG. 8 : step S 828 ). 
   [3-2. Remote Video-Recording Reservation Made Directly From Mobile Phone  10 :  FIG. 13 ] 
   Next, a description is given of the operation of a case in which the mobile phone  10  directly performs remote video-recording reservation on the DVR  20  without using the service server  30 .  FIG. 13  is a sequence diagram showing the flow of information when the mobile phone  10  directly performs remote video-recording reservation on the DVR  20 . 
   Since the processing of each device until the direct-access start response &lt;D- 10 &gt; in the flow of information between the mobile phone  10 , the DVR  20 , the service server  30 , the direct-access management server  40 , and the router  50  shown in  FIG. 13  is the same as the flow described with reference to  FIG. 7 , the description is omitted. 
   A case in which the mobile phone  10  directly performs remote video-recording reservation on the DVR  20  corresponds to a case in which it is determined in step S 918  that the mobile-device direct flag is on and the URI transmitted, as the direct-access URI obtaining response &lt;D- 9 &gt;, from the DVR  20  in step S 1209  is contained in the new remote video-recording reservation response &lt;D- 13 &gt; transmitted from the service server  30  to the mobile phone  10  in step S 919 . Since the mobile phone  10  merely needs to access the direct-access URI received as the new remote video-recording reservation response &lt;D- 13 &gt;, as described above, it is not particularly necessary to determine whether the direct-access URI corresponds to the DVR  20  or the tunneling of the direct-access management server  40 . 
   When the mobile phone  10  receives the new remote video-recording reservation response &lt;D- 13 &gt; containing the direct-access URI from the service server  30  ( FIG. 8 : step S 815 ), the mobile phone  10  accesses the address of the DVR  20 , the address being included in the direct-access URI, and transmits a new remote video-recording reservation request &lt;D- 14 &gt; containing the direct-access URI and the video-recording reservation program information to the DVR  20  (FIG.  8 : step S 816 ). 
   Upon receiving the new remote video-recording reservation request &lt;D- 14 &gt; from the mobile phone  10  ( FIG. 12 : step S 1210 ), the DVR  20  checks the validity of the direct-access URI contained in the new remote video-recording reservation request &lt;D- 14 &gt; ( FIG. 12 : step S 1211 ). When the URI is invalid, the DVR  20  transmits, as a new remote video-recording reservation response &lt;D- 14 R&gt;, an error code indicating so to the mobile phone  10  ( FIG. 12 : step S 1212 ). Examples of a method for checking the validity of the direct-access URI include a method in which a random number that cannot be easily reproduced is added during the issuance of the direct-access URI and it is checked whether or not the random number is included in the direct-access URI in the new remote video-recording reservation request &lt;D- 14 &gt;. When the URI is valid, the DVR  20  determines whether or not the video-recording date and time of a video-recording reservation requested by the mobile phone  10  overlaps the video-recording data and time of an already scheduled video-recording reservation, based on the video-recording reservation program information. When there is no overlapping video-recording reservation, the DVR  20  makes a video-recording reservation based on the video-recording reservation program information and creates a reservation overlapping program list indicating that there is no reservation overlapping. When an overlapping video-recording reservation is found, the DVR  20  creates a reservation overlapping program list that contains video-recording date and time, a channel, a program title, and so on of the overlapping video-recording reservation. Thereafter, the DVR  20  transmits a new remote video-recording reservation response &lt;D- 14 R&gt; containing the reservation overlapping program list to the mobile phone  10  ( FIG. 12 : step S 1213 ). 
   Upon receiving the new remote video-recording reservation response &lt;D- 14 R&gt; ( FIG. 8 : step S 817 ), the mobile phone  10  determines whether or not a reservation overlapping program exists based on the reservation overlapping program list ( FIG. 8 : step S 818 ). When a reservation overlapping program exists, the mobile phone  10  displays the information of the reservation overlapping program to the user via the display unit ( FIG. 8 : step S 819 ). When no reservation overlapping program exists, the mobile phone  10  displays a message indicating the success of the remote video-recording reservation to the user via the display unit ( FIG. 8 : step S 820 ). 
   When the mobile phone  10  receives, as the new remote video-recording reservation response &lt;D- 14 R&gt;, the invalid-URI error code ( FIG. 8 : step S 821 ), the mobile phone  10  displays an error message indicating the failure of the direct access to the user via the display unit ( FIG. 8 : step S 822 ). 
   [3-3. Remote Video-Recording Reservation From Service Server  30  by Using Tunneling:  FIG. 14 ] 
   Next, a description is given of the operation of a case in which the service server  30  receives an instruction from the mobile phone  10  to perform remote video-recording reservation on the DVR  20  by using tunneling performed by the XMPP server  43  of the direct-access management server  40 .  FIG. 14  is a sequence diagram showing the flow of information when the service server  30  that has received an instruction from the mobile phone  10  performs remote video-recording reservation on the DVR  20  by using tunneling performed by the XMPP server  43 . 
   Since the processing of each device until the direct-access start response &lt;D- 10 &gt; in the flow of information between the mobile phone  10 , the DVR  20 , the service server  30 , the direct-access management server  40 , and the router  50  shown in  FIG. 14  is the same as the flow described with reference to  FIG. 7 , the description is omitted. 
   A case in which the service server  30  that has received an instruction from the mobile phone  10  performs remote video-recording reservation on the DVR  20  by using tunneling performed by the XMPP server  43  corresponds to a case in which it is determined in step S 918  that the mobile-device direct flag is off and the direct-access start response &lt;D- 10 &gt; received by the service server  30  in step S 917  contains an URI for tunneling, the URI being assigned by the direct-access management server  40  in step S 1110 . Since the service server  30  merely needs to access the direct-access URI received as the direct-access start response &lt;D- 10 &gt;, as described above, it is not particularly necessary to determine whether the direct-access URI corresponds to the DVR  20  or the tunneling of the direct-access management server  40 . 
   The service server  30  accesses the address of the direct-access management server  40 , the address being included in the direct-access URI received in step S 917  as the direct-access start response &lt;D- 10 &gt;, and transmits a new remote video-recording reservation request &lt;D- 15 &gt; containing the direct-access URI and the video-recording reservation program information obtained from the new remote video-recording reservation request &lt;D- 4 &gt; transmitted from the mobile phone  10  ( FIG. 9 : step S 920 ). 
   When the direct-access management server  40  receives the new remote video-recording reservation request &lt;D- 15 &gt; containing the direct-access URI and the video-recording reservation program information ( FIG. 11 : step S 1112 ), the direct-access management server  40  checks the direct-access URI contained in the new remote video-recording reservation request &lt;D- 15 &gt; ( FIG. 11 : step S 1113 ). When the direct-access URI is invalid, the direct-access management server  40  transmits, as a new remote video-recording reservation response &lt;D- 17 &gt;, an error code indicating that the URI is invalid to the service server  30  ( FIG. 11 : step S 1114 ). When the direct-access URI is valid, the direct-access management server  40  transmits a new remote video-recording reservation request &lt;D- 16 &gt; containing the video-recording reservation program information to the DVR  20  via the XMPP server  43  ( FIG. 11 : step S 1115 ). In this case, for example, all address portions of the direct-access URI are filled with “0s” so that the DVR  20  can recognize that the access is performed by tunneling via the XMPP server  43  in the direct-access management server  40 . 
   Upon receiving the new remote video-recording reservation request &lt;D- 16 &gt; from the direct-access management server  40  ( FIG. 12 : step S 1210 ), the DVR  20  checks the validity of the direct-access URI contained in the new remote video-recording reservation request &lt;D- 16 &gt; ( FIG. 12 : step S 1211 ). When the direct-access URI is invalid, the DVR  20  transmits, as a new remote video-recording reservation response &lt;D- 16 R&gt;, an error code indicating so to the direct-access management server  40  ( FIG. 12 : step S 1212 ). When the direct-access URI is valid the DVR  20  transmits, as a new remote video-recording reservation response &lt;D- 16 R&gt;, information containing the reservation overlapping program list to the direct-access management server  40  ( FIG. 12 : step S 1213 ). 
   Upon receiving the new remote video-recording reservation response &lt;D- 16 R&gt; containing the reservation overlapping program list from the DVR  20  ( FIG. 11 : step S 1116 ), the direct-access management server  40  transmits a new remote video-recording reservation response &lt;D- 17 &gt; containing the reservation overlapping program list to the service server  30  ( FIG. 11 : step S 1117 ). 
   Upon receiving the new remote video-recording reservation response &lt;D- 17 &gt; containing the reservation overlapping program list ( FIG. 9 : step S 921 ), the service server  30  transmits a new remote video-recording reservation response &lt;D- 18 &gt; containing the reservation overlapping program list to the mobile phone  10  ( FIG. 9 : step S 922 ). When the service server  30  receives, as the new remote video-recording reservation response &lt;D- 17 &gt;, the error code from the direct-access management server  40  ( FIG. 9 : step S 923 ), the service server  30  transmits, as a new remote video-recording reservation response &lt;D- 18 &gt;, the error code to the mobile phone  10  ( FIG. 9 : step S 924 ). Subsequent processing of the service server  30  and the mobile phone  10  is the same as the processing described above. 
   [3-4. Remote Video-Recording Reservation From Mobile Phone by Using Tunneling:  FIG. 26 ] 
   Next, a description is given of the operation of a case in which the mobile phone  10  performs remote video-recording reservation on the DVR  20  by using tunneling performed by the XMPP server  43  of the direct-access management server  40  without using the service server  30 .  FIG. 26  is a sequence diagram showing the flow of information when the mobile phone  10  performs remote video-recording reservation on the DVR  20  by using tunneling performed by the XMPP server  43  without using the service server  30 . 
   Since the processing of each device until the direct-access start response &lt;D- 10 &gt; in the flow of information between the mobile phone  10 , the DVR  20 , the service server  30 , the direct-access management server  40 , and the router  50  shown in  FIG. 26  is the same as the flow described with reference to  FIG. 7 , the description is omitted. 
   A case in which the mobile phone  10  performs remote video-recording reservation on the DVR  20  by using tunneling performed by the XMPP server  43  without using the service server  30  corresponds to a case in which it is determined in step S 918  that the mobile-device direct flag is off and the new remote video-recording reservation response &lt;D- 13 &gt; transmitted from the service server  30  to the mobile phone  10  in step S 919  contains an URI for tunneling, the URI being assigned by the direct-access management server  40  in step S 1110 . Since the mobile phone  10  merely needs to access the direct-access URI received as the new remote video-recording reservation response &lt;D- 13 &gt;, as described above, it is not particularly necessary to determine whether the direct-access URI corresponds to the DVR  20  or the tunneling of the direct-access management server  40 . 
   First, when the mobile phone  10  receives the new remote video-recording reservation response &lt;D- 13 &gt; containing the direct-access URI from the service server  30  ( FIG. 8 : step S 815 ), the mobile phone  10  accesses the address of the direct-access management server  40 , the address being included in the direct-access URI, and transmits a new remote video-recording reservation request &lt;D- 55 &gt; containing the direct-access URI and the video-recording reservation program information to the direct-access management server  40  ( FIG. 8 : step S 816 ). 
   Upon receiving the new remote video-recording reservation request &lt;D- 55 &gt; from the mobile phone  10  ( FIG. 11 : step S 1112 ), the direct-access management server  40  checks the direct-access URI contained in the new remote video-recording reservation request &lt;D- 55 &gt; ( FIG. 11 : step S 1113 ). When the direct-access URI is invalid, the direct-access management server  40  transmits, as a new remote video-recording reservation response &lt;D- 57 R&gt;, an error code indicating that the URI is invalid to mobile phone  10  ( FIG. 11 : step S 1114 ). When the direct-access URI is valid, the direct-access management server  40  transmits a new remote video-recording reservation request &lt;D- 16 &gt; containing the video-recording reservation program information to the DVR  20  via the XMPP server  43  ( FIG. 11 : step S 1115 ). In this case, for example, all address portions of the direct-access URI are filled with “0s” so that the DVR  20  can recognize that the access is performed by tunneling via the XMPP server  43  in the direct-access management server  40 . 
   Upon receiving the new remote video-recording reservation request &lt;D- 16 &gt; from the direct-access management server  40  ( FIG. 12 : step S 1210 ), the DVR  20  checks the validity of the direct-access URI contained in the new remote video-recording reservation request &lt;D- 16 &gt; ( FIG. 12 : step S 1211 ). When the direct-access URI is invalid, the DVR  20  transmits, as a new remote video-recording reservation response &lt;D- 16 R&gt;, an error code indicating so to the direct-access management server  40  ( FIG. 12 : step S 1212 ). When the direct-access URI is valid, the DVR  20  transmits, as a new remote video-recording reservation response &lt;D- 16 R&gt;, information containing the reservation overlapping program list to the direct-access management server  40  ( FIG. 12 : step S 1213 ). 
   Upon receiving the new remote video-recording reservation response &lt;D- 16 R&gt; containing the reservation overlapping program list from the DVR  20  ( FIG. 11 : step S 1116 ), the direct-access management server  40  transmits a new remote video-recording reservation response &lt;D- 57 R&gt; containing the reservation overlapping program list to the mobile phone  10  ( FIG. 11 : step S 1117 ). When the direct-access management server  40  receives the error code as the new remote video-recording reservation response &lt;D- 16 R&gt; from the DVR  20 , the direct-access management server  40  transmits, as a new remote video-recording reservation response &lt;D- 57 R&gt;, the error code to the mobile phone  10 . Subsequent processing of the mobile phone  10  is the same as the processing described above. 
   As described above, the mobile phone  10  can perform video-recording reservation processing on the DVR  20  by using not only direct access to the DVR  20  but also proxy access performed by the service server  30 , XMPP-based tunneling performed by the direct-access management server  40 , and so on. 
   [4. Content Acquirement] 
   Next, a description will be given of the operation of a case in which the mobile phone  10  acquires content from the DVR  20 .  FIG. 15  is a sequence diagram showing the flow of information when the mobile phone  10  directly accesses the DVR  20  to acquire content.  FIG. 17  is a flow chart showing the operation of the mobile phone  10  during the acquirement of content.  FIGS. 18 and 19  are flow charts showing the operation of the service server  30  during the acquirement of content. 
   When the user of the mobile phone  10  gives a direct-access use start instruction to the mobile phone  10  in order to receive a content acquiring service ( FIG. 17 : step S 1701 ), the mobile phone  10  transmits a controlled-device-list obtaining request &lt;D- 1 &gt; containing the user identification information preset in the mobile phone  10  to the service server  30  ( FIG. 17 : step S 1702 ). 
   Upon receiving the controlled-device-list obtaining request &lt;D- 1 &gt; from the mobile phone  10  ( FIG. 9 : step S 901 ), the service server  30  determines whether or not a controlling-device/service management ID corresponding to the user identification information contained in the controlled-device-list obtaining request &lt;D- 1 &gt; is stored in the storage unit  31  ( FIG. 9 : step S 902 ). When a controlling-device/service management ID corresponding to the user identification information is not stored in the storage unit  31 , the service server  30  transmits, as a controlled-device-list obtaining response &lt;D- 3 &gt;, an error code indicating that the registration of a controlled device for the service is required to the mobile phone  10  ( FIG. 9 : step S 903 ). When a controlling-device/service management ID corresponding to the user identification information is stored in the storage unit  31 , the service server  30  transmits a controlled-device-list obtaining request &lt;D- 2 &gt; containing the controlling-device/service management ID and a service ID, which is information for identifying the service, to the direct-access management server  40  ( FIG. 9 : step S 904 ) in order to obtain a list of controlled devices associated with the controlling-device/service management ID managed by the direct-access management server  40 . 
   Upon receiving the controlled-device-list obtaining request &lt;D- 2 &gt; from the service server  30  ( FIG. 10 : step S 1012 ), the direct-access management server  40  determines whether or not a combination of the service ID and the controlling-device/service management ID which are contained in the controlled-device-list obtaining request &lt;D- 2 &gt; matches what is stored in the storage unit  41  ( FIG. 10 : step S 1013 ). If the combination is not stored, the direct-access management server  40  transmits, as a controlled-device-list obtaining response &lt;D- 2 R&gt;, an error code indicating the combination is not registered to the service server  30  ( FIG. 10 : step S 1014 ). When it is determined that the combination of the service ID and the controlling-device/service management ID contained in the controlled-device-list obtaining request &lt;D- 2 &gt; is stored in the storage unit  41 , the direct-access management server  40  generates, as a controlled-device list, a list containing numbers re-assigned for the controlled-device management IDs of controlled devices controllable by the mobile phone  10 , device names contained in the device authentication information of the controlled devices, and so on in accordance with the linking contents of the controlling-device/service management ID and the controlled-device management ID which are stored in the storage unit  41 . The direct-access management server  40  then stores the controlled-device list in the storage unit  41  in association with controlling-device/service management ID and transmits a controlled-device-list obtaining response &lt;D- 2 R&gt; containing the controlled-device list to the service server  30  ( FIG. 10 : step S 1015 ). 
   Upon receiving, as the controlled-device-list obtaining response &lt;D- 2 R&gt;, the error code indicating the combination is not registered from the direct-access management server  40  ( FIG. 9 : step S 905 ), the service server  30  transmits, as a controlled-device-list obtaining response &lt;D- 3 &gt;, an error code indicating that controlled-device registration is required to the mobile phone  10  ( FIG. 9 : step S 906 ). When the service server  30  receives the controlled-device-list obtaining response &lt;D- 2 R&gt; containing the controlled-device list from the direct-access management server  40  ( FIG. 9 : step S 907 ), the service server  30  transmits a controlled-device-list obtaining response &lt;D- 3 &gt; containing the controlled-device list to the mobile phone  10  ( FIG. 9 : step S 908 ). 
   When the mobile phone  10  receives, as the controlled-device-list obtaining response &lt;D- 3 &gt;, the error code from the service server  30  ( FIG. 17 : step S 1703 ), the mobile phone  30  displays an error message indicating that controlled-device registration is required to the user via the display unit ( FIG. 17 : step S 1704 ). When the mobile phone  10  receives the controlled-device-list obtaining response &lt;D- 3 &gt; containing the controlled-device list ( FIG. 17 : step S 1705 ), it determines whether or not multiple controlled-device numbers exist in the controlled-device list ( FIG. 17 : step S 1706 ). When multiple controlled-device numbers exist, the mobile phone  10  displays the contents of the controlled-device list on the display unit ( FIG. 17 : step S 1707 ), prompts the user to select one of the controlled-device numbers ( FIG. 17 : step S 1708 ), and stores the selected controlled-device number in the storage unit  11  ( FIG. 17 : steps S 1709  and S 1710 ). When multiple controlled devices do not exist, the number of the one controlled device is stored in the storage unit  11  ( FIG. 17 : steps S 1711  and S 1710 ). 
   Next, based on the mobile-device direct flag preset in the mobile phone  10 , the mobile phone  10  determines whether to directly access the content acquiring service of the DVR  20  from the mobile phone  10  or to access the content acquiring service via the service server  30 , and then branches the process ( FIG. 17 : step S 1712 ). 
   When the mobile phone  10  directly access the content acquiring service of the DVR  20 , the mobile phone  10  transmits a content search request &lt;D- 44 &gt; containing the user identification information, search conditions, the controlled-device number, and the mobile-device direct flag (on) to the service server  30  ( FIG. 17 : step S 1713 ). When the mobile phone  10  acquires content via the service server  30 , the mobile phone  10  transmits a content search request &lt;D- 44 &gt; containing the user identification information, search conditions, the controlled-device number, and the mobile-device direct flag (off) to the service server  30  ( FIG. 17 : step S 1724 ). In this case, the search conditions refer to conditions for searching for content and include, for example, a condition indicating that the content is still-image data and information specifying that the content is recorded-video data or the like. Items such as date and a data size may be added as search conditions so that more detailed search conditions can be set. 
   Upon receiving the content search request &lt;D- 44 &gt; from the mobile phone  10  ( FIG. 18 : step S 1801 ), the service server  30  checks whether or not an available XMPP session ID is stored in the storage unit  31  ( FIG. 18 : step S 1802 ). When an available XMPP session ID is already stored in the storage unit  31 , the service server  30  stores the value of the mobile-device direct flag, contained in the content search request &lt;D- 44 &gt;, in the storage unit  31  in association with the service ID, the controlling-device/service management ID, and the controlled-device number ( FIG. 18 : step S 1803 ). When an available XMPP session ID is not stored, the service server  30  transmits an XMPP login request &lt;D- 5 &gt; containing the service ID, the controlling-device/service management ID, and the controlled-device number to the direct-access management server  40  ( FIG. 18 : step S 1804 ) in order to establish an XMPP session with the XMPP server  43 . 
   Upon receiving the XMPP login request &lt;D- 5 &gt; from the service server  30  ( FIG. 10 : step S 1016 ), the direct-access management server  40  determines whether or not a combination of the service ID, the controlling-device/service management ID, and the controlled-device number which are contained in the XMPP login request &lt;D- 5 &gt; is stored in the storage unit  41  ( FIG. 10 : step S 1017 ). When the combination is not stored, the direct-access management server  40  transmits, as an XMPP login response &lt;D- 5 R&gt;, an error code indicating that a controlled device for the corresponding service does not exist to the service server  30  ( FIG. 10 : step S 1018 ). When a controlled device for the corresponding service is stored in the storage unit  41 , the direct-access management server  40  generates and stores an XMPP session ID ( FIG. 10 : step S 1019 ) and transmits an XMPP login response &lt;D- 5 R&gt; containing the XMPP session ID to the service server  30  ( FIG. 10 : step S 1020 ). 
   Upon receiving the XMPP login response &lt;D- 5 R&gt; containing the XMPP session ID from the direct-access management server  40  ( FIG. 18 : step S 1805 ), the service server  30  stores the XMPP session ID contained in the XMPP login response &lt;D- 5 R&gt; and the value of the mobile-device direct flag contained in the content search request &lt;D- 44 &gt; received in step S 1801  in the storage unit  31  in association with the service ID, the controlling-device/service management ID, and the controlled-device list number ( FIG. 18 : step S 1806 ). 
   After the mobile-device direct flag is stored in step S 1803  or step S 1806 , the service server  30  transmits a direct-access start request &lt;D- 6 &gt; containing the service ID, the controlling-device/service management ID, a service URN (uniform resource name), and the XMPP session ID to the direct-access management server  40  ( FIG. 18 : step S 1807 ). In this case, since the mobile phone  10  is to acquire content from the DVR  20 , the service URN is information specifying the content acquiring service. 
   Upon receiving the direct-access start request &lt;D- 6 &gt; from the service server  30  ( FIG. 11 : step S 1101 ), the direct-access management server  40  determines whether or not a combination of the service ID and the controlling-device/service management ID which are contained in the direct-access start request &lt;D- 6 &gt; is stored in the storage unit  41  ( FIG. 11 : step S 1102 ). When the combination is not stored, the direct-access management server  40  transmits, as a direct-access start response &lt;D- 10 &gt;, an error code indicating that controlled-device registration is required to the service server  30  ( FIG. 11 : step S 1103 ). When the combination of the service ID and the controlling-device/service management ID contained in the direct-access start request &lt;D- 6 &gt; is stored in the storage unit  41 , the direct-access management server  40  determines whether or not the XMPP session ID contained in the direct-access start request &lt;D- 6 &gt; is stored in the storage unit  41  in association with the combination of the service ID and the controlling-device/service management ID contained in the direct-access start request &lt;D- 6 &gt; ( FIG. 11 : step S 1104 ). When it is not stored, the direct-access management server  40  transmits, as a direct-access start response &lt;D- 10 &gt;, an error code indicating that the XMPP session ID is invalid to the service server  30  ( FIG. 11 : step S 1105 ). When the XMPP session ID contained in the direct-access start request &lt;D- 6 &gt; is stored in the storage unit  41  in association with the combination of the service ID and the controlling-device/service management ID contained in the direct-access start request &lt;D- 6 &gt;, the direct-access management server  40  transmits a direct-access URI obtaining request &lt;D- 7 &gt; containing the designation information of the service URN specified by the direct-access start request &lt;D- 6 &gt; to the DVR  20  via the XMPP server  43  in the direct-access management server  40  ( FIG. 11 : step S 1106 ). 
   When the service server  30  receives, as the direct-access start response &lt;D- 10 &gt;, the error code indicating that the XMPP session ID is invalid from the direct-access management server  40  ( FIG. 18 : step S 1808 ), the process returns to step S 1804  and the service server  30  re-transmits the XMPP login request &lt;D- 5 &gt; to the direct-access management server  40  to re-establish an XMPP session. 
   Upon receiving the direct-access URI obtaining request &lt;D- 7 &gt; containing the service-URN designation information from the direct-access management server  40  ( FIG. 12 : step S 1201 ), the DVR  20  assigns a direct-access local port ( FIG. 12 : step S 1202 ). Next, the DVR  20  transmits, to the router  50 , a NAT setting request &lt;D- 8 &gt; for a direct-access port. The NAT setting request &lt;D- 8 &gt; contains a local IP address pre-assigned to the DVR  20  and the port number of the direct-access local port. The DVR  20  then issues, to the router  50 , a request for mapping a port number and a global IP address accessible from the Internet to the port number and the local IP address ( FIG. 12 : step S 1203 ). 
   When the DVR  20  receives, as a direct-access-port NAT setting response &lt;D- 8 R&gt;, a global-IP-address and port-number obtaining error from the router  50  ( FIG. 12 : step S 1204 ) in response to the direct-access-port NAT setting request &lt;D- 8 &gt; in step S 1203 , the DVR  20  determines whether or not the service URN can be tunneled ( FIG. 12 : step S 1205 ) based on the service-URN designation information obtained in step S 1201 . Thus, when it is determined that the service URN contained in the direct-access URI obtaining request &lt;D- 7 &gt; is a service URN that can be tunneled, the DVR  20  transmits, as a direct-access URI obtaining response &lt;D- 9 &gt;, an error code that gives an instruction for tunneling to the direct-access management server  40  ( FIG. 12 : step S 1206 ). When the service-URN designation information contained in the direct-access URI obtaining request &lt;D- 7 &gt; indicates a service URN that cannot be tunneled, the DVR  20  transmits, as a direct-access URI obtaining response &lt;D- 9 &gt;, an error code indicating the failure of acquiring an available port to the direct-access management server  40  ( FIG. 12 : step S 1207 ). In this case, since the amount of data transferred in the content acquiring service is larger than that in the remote video-recording reservation service, the service URN cannot be tunneled. However, the present invention is not limited to the configuration. The service provider can appropriately set whether or not the tunneling is possible, depending on the capability of the direct-access management server  40 . 
   When the DVR  20  receives, as a NAT setting response &lt;D- 8 R&gt;, a global IP address and a port number associated with the local IP address and the port number of the DVR  20  from the router  50  ( FIG. 12 : step S 1208 ) in response to the direct-access-port NAT setting request &lt;D- 8 &gt;, the DVR  20  uses the global IP address and the port number to create a direct-access URI list and transmits, as a direct-access URI obtaining response &lt;D- 9 &gt;, the direct-access URI list to the direct-access management server  40  ( FIG. 12 : step S 1209 ). 
   Upon receiving the direct-access URI list as the direct-access URI obtaining response &lt;D- 9 &gt; ( FIG. 11 : step S 1107 ), the XMPP server  43  of the direct-access management server  40  transmits, as a direct-access start response &lt;D- 10 &gt;, the direct-access URI list to the service server  30  ( FIG. 11 : step S 1111 ). 
   When the direct-access management server  40  receives, as the direct-access URI obtaining response &lt;D- 9 &gt;, the error code that gives an instruction for content acquirement using tunneling ( FIG. 11 : step S 1109 ), the direct-access management server  40  assigns a tunneling port in the direct-access management server  40  ( FIG. 11 : step S 1110 ), uses the port number of the assigned tunneling port in the direct-access management server  40  and the global IP address of the direct-access management server  40  to create a direct-access URI list, and transmits a direct-access start response &lt;D- 10 &gt; containing the direct-access URI list to the service server  30  ( FIG. 11 : step S 1111 ). 
   Upon receiving the direct-access start response &lt;D- 10 &gt; from the direct-access management server  40  ( FIG. 18 : step S 1809 ), the service server  30  determines whether the mobile-device direct flag is on or off ( FIG. 18 : step S 1810 ). When the mobile-device direct flag is on, the service server  30  transmits a content search response &lt;D- 20 &gt; containing the direct-access URI to the mobile phone  10  ( FIG. 18 : step S 1811 ) in order to allow the mobile phone  10  to directly access a device specified by the direct-access URI. When the mobile-device direct flag is off, the service server  30  transmits a content search request &lt;D- 19 &gt; containing the direct-access URI and the search conditions, obtained from content search request &lt;D- 44 &gt; transmitted from the mobile phone  10 , to the direct-access URI of the DVR  20  ( FIG. 18 : step S 1812 ). 
   Some specific examples in which the mobile phone  10  issues a content acquiring request to the DVR  20  will be described below. 
   [4-1. Direct Access from Mobile Phone  10 :  FIG. 15 ] 
   Next, a description will be given of the operation of a case in which the mobile phone  10  directly acquires content from the DVR  20  without using the service server  30 .  FIG. 15  is a sequence diagram showing the flow of information when the mobile phone  10  directly acquires content from the DVR  20 . 
   In the flow of information between the mobile phone  10 , the DVR  20 , the service server  30 , the direct-access management server  40 , and the router  50  shown in  FIG. 15 , the processing of each device until the direct-access start response &lt;D- 10 &gt; is the same as the processing described above. 
   The case in which the mobile phone  10  directly acquires content from the DVR  20  refers to a case in which it is determined in step S 1810  that the mobile-device direct flag is on and tunneling at the direct-access management server  40  is not performed. 
   First, a description will be given of the flow of a case in which the mobile phone  10  directly issues a content search request to the DVR  20  to obtain a title list of content that matches search conditions. 
   When the mobile phone  10  receives the content search response &lt;D- 20 &gt; containing the direct-access URI from the service server  30  ( FIG. 17 : step S 1714 ), the mobile phone  10  accesses the address of the DVR  20 , the address being included in the direct-access URI, and transmits a content search request &lt;D- 29 &gt; containing the direct-access URI and search conditions to the DVR  20  ( FIG. 17 : step S 1715 ). 
   Upon receiving the content search request &lt;D- 29 &gt; containing the direct-access URI and the search conditions from the mobile phone  10  ( FIG. 12 : step S 1214 ), the DVR  20  checks the validity of the direct-access URI contained in the content search request &lt;D- 29 &gt; ( FIG. 12 : step S 1215 ). When the URI is invalid, the DVR  20  transmits, as a content search response &lt;D- 29 R&gt;, an error code indicating that the URI is invalid to the mobile phone  10  ( FIG. 12 : step S 1216 ). When the URI is valid, the DVR  20  searches the storage unit  21  for content that matches the search conditions in accordance with the search conditions in the content search request &lt;D- 29 &gt; and generates a title list of content and a list of local URIs based on the search result. Thereafter, the DVR  20  transmits, as a content search response &lt;D- 29 R&gt;, the generated title list and local-URI list to the mobile phone  10  ( FIG. 12 : step S 1217 ). The local URI in this case refers to information (URI) indicating the local storage location of content. For example, the local URI refers to information indicating a storage location in the storage unit  21 , the storage location being identified by a local specifying method in the DVR  20 , or information indicating a storage location in a home network, the storage location being identified by a local address in the home network to which the DVR  20  is connected. 
   Upon receiving, as the content search response &lt;D- 29 R&gt;, the error code indicating that the URI(s) is invalid from the DVR  20  ( FIG. 17 : step S 1722 ), the mobile phone  10  displays a message indicating the failure of the direct access to the user via the display unit ( FIG. 17 : step S 1723 ). 
   When the mobile phone  10  receives the content search response &lt;D- 29 R&gt; containing the content title list and the local-URI list from the DVR  20  ( FIG. 17 : step S 1716 ), the process proceeds to processing for content acquirement. 
   Next, a description will be given of the flow of processing for the mobile phone  10  to directly acquire content from the DVR  20 . 
   When the mobile phone  10  receives the content search response &lt;D- 29 R&gt; containing the content title list and the local-URI list from the DVR  20  ( FIG. 17 : step S 1716 ), the mobile phone  10  displays the received content title list on the display unit, extracts a local URI or URIs corresponding to content selected by the user from the displayed titles, and creates a local-URI list for issuing a request for obtaining the content. Thereafter, the mobile phone  10  transmits a URI obtaining request &lt;D- 30 &gt; containing the user identification information, the local-URI list of the selected content, and the controlled-device number to the service server  30  ( FIG. 17 : step S 1717 ). In this case, the reason why the mobile phone  10  re-obtains the URI for directly accessing the DVR  20  is that the local URI obtained in step S 1716  indicates a place that cannot be directly accessed from the Internet. 
   Upon receiving the URI obtaining request &lt;D- 30 &gt; ( FIG. 19 : step S 1901 ), the service server  30  checks whether or not an available XMPP session ID is stored in the storage unit  31  ( FIG. 19 : step S 1902 ). When an available XMPP session ID is not stored, the service server  30  transmits an XMPP login request &lt;D- 5 &gt; to the direct-access management server  40  ( FIG. 19 : step S 1903 ). The service server  30  receives the XMPP login response &lt;D- 5 R&gt; from the direct-access management server  40  ( FIG. 19 : step S 1904 ) and stores the XMPP session ID, contained in the received XMPP login response &lt;D- 5 R&gt;, in the storage unit  31  ( FIG. 19 : step S 1905 ). Thereafter, the service server  30  transmits a direct-access start request &lt;D- 31 &gt; containing the service ID, the controlling-device/service management ID, the service URN, the XMPP session ID, and the content local-URI list to the direct-access management server  40  ( FIG. 19 : step S 1906 ). Also, when an available XMPP session ID is already stored, the service server  30  transmits a direct-access start request &lt;D- 31 &gt; to the direct-access management server  40  ( FIG. 19 : step S 1906 ). In this case, since the mobile phone  10  is to acquire content from the DVR  20 , the service URN is information specifying the content acquiring service. 
   Upon receiving the direct-access start request &lt;D- 31 &gt; ( FIG. 11 : step S 1101 ), the direct-access management server  40  determines whether or not a combination of the service ID and the controlling-device/service management ID which are contained therein is stored in the storage unit  41  ( FIG. 11 : step S 1102 ). When the combination is not stored, the direct-access management server  40  transmits, as a direct-access start response &lt;D- 35 &gt;, an error code indicating controlled-device registration is required to the service server  30  ( FIG. 11 : step S 1103 ). When the combination of the service ID and the controlling-device/service management ID is stored in the storage unit  41 , the direct-access management server  40  determines whether or not the XMPP session ID contained in the direct-access start request &lt;D- 31 &gt; is stored in the storage unit  41  in association with the combination of the service ID and the controlling-device/service management ID contained in the direct-access start request &lt;D- 31 &gt; ( FIG. 11 : step S 1104 ). When it is not stored, the direct-access management server  40  transmits, as a direct-access start response &lt;D- 35 &gt;, an error code indicating that the XMPP session ID is invalid to the service server  30  ( FIG. 11 : step S 1105 ). When the XMPP session ID is stored in the storage unit  41  in association with the combination of the service ID and the controlling-device/service management ID, the direct-access management server  40  transmits a direct-access URI obtaining request &lt;D- 32 &gt;, which contains the service URN and the local-URI list specified by the direct-access start request &lt;D- 31 &gt;, to the DVR  20  ( FIG. 11 : step S 1106 ). 
   When the service server  30  receives, as the direct-access start response &lt;D- 35 &gt;, the error code indicating that the XMPP session ID is invalid from the direct-access management server  40  ( FIG. 19 : step S 1907 ), the process returns to step S 1903 . The service server  30  then re-issues the XMPP login request &lt;D- 5 &gt; to the direct-access management server  40  and receives an XMPP login response &lt;D- 5 R&gt; from the direct-access management server  40  ( FIG. 19 : step S 1904 ). The service server  30  then stores the XMPP session ID, contained in the XMPP login response &lt;D- 5 R&gt;, in the storage unit  41  ( FIG. 19 : step S 1905 ). 
   Upon receiving the direct-access URI obtaining request &lt;D- 32 &gt; from the direct-access management server  40  ( FIG. 12 : step S 1201 ), the DVR  20  assigns a direct-access local port ( FIG. 12 : step S 1202 ). Next, the DVR  20  transmits a direct-access-port NAT setting request &lt;D- 33 &gt; containing a local IP address and the port number of the direct-access local port to the router  50  ( FIG. 12 : step S 1203 ). 
   When the DVR  20  receives, as a NAT setting response &lt;D- 33 R&gt;, a global-IP-address and port-number obtaining error from the service server  30  via the router  50  ( FIG. 12 : step S 1204 ), the DVR  20  determines whether or not the service URN can be tunneled ( FIG. 12 : step S 1205 ) based on the service-URN designation information obtained in step S 1201 . When it is determined that the service URN can be tunneled, the DVR  20  transmits, as a direct-access URI obtaining response &lt;D- 34 &gt;, an error code that gives an instruction for tunneling to the direct-access management server  40  ( FIG. 12 : step S 1206 ). When the service-URN designation information indicates that the service URN cannot be tunneled, the DVR  20  transmits, as a direct-access URI obtaining response &lt;D- 34 &gt;, an error code indicating the failure of acquiring an available port to the direct-access management server  40  ( FIG. 12 : step S 1207 ). 
   When the DVR  20  receives, as a NAT setting response &lt;D- 33 R&gt;, a global IP address and a port number associated with the local IP address and the port number of the DVR  20  from the router  50  ( FIG. 12 : step S 1208 ) in response to the direct-access-port NAT setting request &lt;D- 3 &gt;, the DVR  20  uses the global IP address and the port number to create a direct-access URI list and transmits, as a direct-access URI obtaining response &lt;D- 34 &gt;, the direct-access URI list to the direct-access management server  40  ( FIG. 12 : step S 1209 ). 
   Upon receiving the direct-access URI list as the direct-access URI obtaining response &lt;D- 34 &gt; ( FIG. 11 : step S 1107 ), the XMPP server  43  of the direct-access management server  40  transmits, as a direct-access start response &lt;D- 35 &gt;, the direct-access URI list to the service server  30  ( FIG. 11 : step S 1111 ). 
   When the direct-access management server  40  receives, as the direct-access URI obtaining response &lt;D- 34 &gt;, the error code that gives an instruction for content acquirement using tunneling ( FIG. 11 : step S 1109 ), the direct-access management server  40  assigns a tunneling port in the direct-access management server  40  ( FIG. 11 : step S 1110 ), uses the port number of the assigned tunneling port in the direct-access management server  40  and the global IP address of the direct-access management server  40  to create a direct-access URI list, and transmits a direct-access start response &lt;D- 35 &gt; containing the direct-access URI list to the service server  30  ( FIG. 11 : step S 1111 ). 
   When the service server  30  receives the direct-access start response &lt;D- 35 &gt; containing the direct-access URI list from the direct-access management server  40  ( FIG. 19 : step S 1908 ), the service server  30  transmits an URI obtaining response &lt;D- 36 &gt; containing the direct-access URI list to the mobile phone  10  ( FIG. 19 : step S 1909 ). 
   Since the mobile phone  10  has obtained the direct-access URI for directly acquiring content from the DVR  20  through the processing described above, the mobile phone  10  starts processing for acquiring the selected content from the DVR  20 . The direct-access URI list received by the mobile phone  10  as the URI obtaining response &lt;D- 36 &gt; contains a direct-access URI corresponding to the each content selected by the user. 
   Upon receiving the URI obtaining response &lt;D- 36 &gt; containing the direct-access URI list ( FIG. 17 : step S 1718 ), the mobile phone  10  selects a direct-access URI corresponding to content on which acquiring processing is performed from the direct-access URI list and transmits a content acquiring request &lt;D- 37 &gt; containing the direct-access URI to the DVR  20  ( FIG. 20 : step S 1719 ). 
   Upon receiving the content acquiring request &lt;D- 37 &gt; containing the direct-access URI from the mobile phone  10  ( FIG. 12 : step S 1218 ), the DVR  20  checks the validity of the direct-access URI contained in the content acquiring request &lt;D- 37 &gt; ( FIG. 12 : step S 1219 ). When the URI is invalid, the DVR  20  transmits, as a content acquiring response &lt;D- 37 R&gt;, an error code indicating that the URI is invalid to the mobile phone  10  ( FIG. 12 : step S 1220 ). When the URI is valid, the DVR  20  transmits, as a content obtaining response &lt;D- 37 R&gt;, content specified by the direct-access URI to the mobile phone  10  ( FIG. 12 : step S 1221 ). 
   Upon receiving the content from the DVR  20  as the content acquiring response &lt;D- 37 R&gt; ( FIG. 17 : step S 1720 ), the mobile phone  10  repeats the transmission of the content acquiring request &lt;D- 37 &gt; to the DVR  20  in step S 1719  until the acquirement of all the content contained in the direct-access URI list is completed ( FIG. 17 : step S 1721 ). Upon receiving, as the content acquiring response &lt;D- 37 R&gt;, the error code indicating the URI is invalid from the DVR  20 , the mobile phone  10  displays a message indicating the failure of the direct access to the user via the display unit. 
   [4-2. Content Acquirement via Service Server  30 :  FIG. 16 ] 
   Next, a description will be given of the operation of a case in which the mobile phone  10  acquires content from the DVR  20  via the service server  30 .  FIG. 16  is a sequence diagram showing the flow of information during content acquirement by direct access from the service server  30  to the DVR  20 . 
   Since the processing of each device until the direct-access start response &lt;D- 10 &gt; in the flow of information between the mobile phone  10 , the DVR  20 , the service server  30 , the direct-access management server  40 , and the router  50  shown in  FIG. 16  is the same as the flow described with reference to  FIG. 15 , the description is omitted. 
   The case in which the mobile phone  10  acquires content from the DVR  20  via the service server  30  corresponds to a case in which it is determined in step S 1810  that the mobile-device direct flag is off and tunneling at the direct-access management server  40  is not performed. 
   First, a description will be given of the flow of a case in which the mobile phone  10  directly issues a content search request to the DVR  20  via the service server  30  to obtain a title list of content that matches search conditions. 
   Upon receiving the content search request &lt;D- 19 &gt; that was transmitted from the service server  30  in step S 1812  and that contains the direct-access URI and the search conditions ( FIG. 12 : step S 1214 ), the DVR  20  checks the validity of the direct-access URI contained in the content search request &lt;D- 19 &gt; ( FIG. 12 : step S 1215 ). When the URI is invalid, the DVR  20  transmits, as a content search response &lt;D- 19 R&gt;, an error code indicating that the URI is invalid to the service server  30  ( FIG. 12 : step S 1216 ). When the URI is valid, the DVR  20  searches the storage unit  21  for content that matches the search conditions in accordance with the search conditions in the content search request &lt;D- 19 &gt; and generates a title list of content and a local-URI list based on the search result. Thereafter, the DVR  20  transmits, as a content search response &lt;D- 19 R&gt;, the generated title list and local-URI list to the service server  30  ( FIG. 12 : step S 1217 ). 
   Upon receiving, as the content search response &lt;D- 19 R&gt;, the content title list and the local-URI list from the DVR  20  ( FIG. 18 : step S 1813 ), the service server  30  temporarily stores the content local-URI list ( FIG. 18 : step S 1814 ) and transmits a content search response &lt;D- 20 &gt; containing the content tile list to the mobile phone  10  ( FIG. 18 : step S 1815 ). 
   Also, when the service server  30  receives, as the content search response &lt;D- 19 R&gt;, the error code indicating the URI is invalid from the DVR  20  ( FIG. 18 : step S 1816 ), the service server  30  transmits the error code to the mobile phone  10  as a content search response &lt;D- 20 &gt; ( FIG. 18 : step S 1817 ). 
   Upon receiving, as the content search response &lt;D- 20 &gt;, the error code indicating the URI is invalid from the service server  30  ( FIG. 17 : step S 1728 ), the mobile phone  10  displays a message indicating the failure of the direct access to the user via the display unit ( FIG. 17 : step S 1729 ). When the mobile phone  10  receives, as the content search response &lt;D- 20 &gt; the content title list from the service server  30  ( FIG. 17 : step S 1725 ), the process proceeds to processing for content acquirement. 
   Next, a description will be given of the flow of processing for the mobile phone  10  to acquire content from the DVR  20  via the service server  30 . 
   When the mobile phone  10  receives the content search response &lt;D- 20 &gt; containing the content title list from the service server  30  ( FIG. 17 : step S 1725 ), the mobile phone  10  displays the received content title list on the display unit, extracts a title or titles corresponding to content selected by the user from the displayed titles, and creates an obtained-title list for issuing a request for obtaining the content. 
   Thereafter, the mobile phone  10  transmits a content acquiring request &lt;D- 21 &gt; containing the user identification information, the selected-content title list (the obtained-title list), and the controlled-device number to the service server  30  ( FIG. 17 : step S 1726 ). Upon receiving the content acquiring request &lt;D- 21 &gt; ( FIG. 18 : step S 1818 ), the service server  30  searches the storage unit  31  for a local-URI list of content corresponding to the title list contained in the content acquiring request &lt;D- 21 &gt; ( FIG. 18 : step S 1819 ), extracts a local URI or URIs corresponding to the title(s) of content selected by the user, and creates a local-URI list for issuing a request for obtaining the content. 
   Next, the service server  30  checks whether or not an available XMPP session ID is stored in the storage unit  31  ( FIG. 18 : step S 1820 ). When an available XMPP session ID is not stored, the service server  30  transmits an XMPP login request &lt;D- 5 &gt; to the direct-access management server ( FIG. 18 : step S 1821 ). Upon receiving the XMPP login response &lt;D- 5 R&gt; from the direct-access management server ( FIG. 18 : step S 1822 ), the service server  30  stores the XMPP session ID, contained in the received XMPP login response &lt;D- 5 R&gt;, in the storage unit  31  ( FIG. 18 : step S 1823 ). Thereafter, the service server  30  transmits a direct-access start request &lt;D- 22 &gt; containing the service ID, the controlling-device/service management ID, the service URN, the XMPP session ID, and the content local-URI list to the direct-access management server  40  ( FIG. 18 : step S 1824 ). Also, when an available XMPP session ID is already stored, the service server  30  transmits the direct-access start request &lt;D- 22 &gt; to the direct-access management server  40  ( FIG. 18 : step S 1824 ). In this case, since the mobile phone  10  is to acquire content from the DVR  20 , the service URN is information specifying the content acquiring service. 
   Upon receiving the direct-access start request &lt;D- 22 &gt; ( FIG. 11 : step S 1101 ), the direct-access management server  40  determines whether or not a combination of the service ID and the controlling-device/service management ID which are contained therein is stored in the storage unit  41  ( FIG. 11 : step S 1102 ). When the combination is not stored, the direct-access management server  40  transmits, as a direct-access start response &lt;D- 26 &gt;, an error code indicating controlled-device registration is required to the service server  30  ( FIG. 11 : step S 1103 ). When the combination of the service ID and the controlling-device/service management ID is stored in the storage unit  41 , the direct-access management server  40  determines whether or not the XMPP session ID contained in the direct-access start request &lt;D- 22 &gt; is stored in the storage unit  41  in association with the combination of the service ID and the controlling-device/service management ID contained in the direct-access start request &lt;D- 22 &gt; ( FIG. 11 : step S 1104 ). When it is not stored, the direct-access management server  40  transmits, as a direct-access start response &lt;D- 26 &gt;, an error code indicating that the XMPP session ID is invalid to the service server  30  ( FIG. 11 : step S 1105 ). When the XMPP session ID is stored in the storage unit  41  in association with the combination of the service ID and the controlling-device/service management ID, the direct-access management server  40  transmits a direct-access URI obtaining request &lt;D- 23 &gt;, which contains the service URN and the local-URI list specified by the direct-access start request &lt;D- 31 &gt;, to the DVR  20  ( FIG. 11 : step S 1106 ). 
   When the service server  30  receives, as the direct-access start response &lt;D- 26 &gt;, the error code indicating that the XMPP session ID is invalid from the direct-access management server  40  ( FIG. 18 : step S 1825 ), the process returns to step S 1820  and the service server  30  re-checks whether or not an available XMPP session ID is stored in the storage unit  31 . 
   Upon receiving the direct-access URI obtaining request &lt;D- 23 &gt; from the direct-access management server  40  ( FIG. 12 : step S 1201 ), the DVR  20  assigns a direct-access local port ( FIG. 12 : step S 1202 ). Next, the DVR  20  transmits a direct-access-port NAT setting request &lt;D- 24 &gt; containing a local IP address and the port number of the direct-access local port to the router  50  ( FIG. 12 : step S 1203 ). 
   When the DVR  20  receives, as a NAT setting response &lt;D- 24 R&gt;, a global-IP-address and port-number obtaining error from the service server  30  via the router  50  ( FIG. 12 : step S 1204 ), the DVR  20  determines whether or not the service URN can be tunneled ( FIG. 12 : step S 1205 ) based on the service-URN designation information obtained in step S 1201 . When it is determined that the service URN can be tunneled, the DVR  20  transmits, as a direct-access URI obtaining response &lt;D- 25 &gt;, an error code that gives an instruction for tunneling to the direct-access management server  40  ( FIG. 12 : step S 1206 ). When the service-URN designation information indicates that the service URN cannot be tunneled, the DVR  20  transmits, as a direct-access URI obtaining response &lt;D- 25 &gt;, an error code indicating the failure of acquiring an available port to the direct-access management server  40  ( FIG. 12 : step S 1207 ). 
   When the DVR  20  receives, as a NAT setting response &lt;D- 24 R&gt;, a global IP address and a port number associated with the local IP address and the port number of the DVR  20  from the router  50  ( FIG. 12 : step S 1208 ) in response to the direct-access-port NAT setting request &lt;D- 24 &gt;, the DVR  20  uses the global IP address and the port number to create a direct-access URI list and transmits, as a direct-access URI obtaining response &lt;D- 25 &gt;, the direct-access URI list to the direct-access management server  40  ( FIG. 12 : step S 1209 ). 
   Upon receiving the direct-access URI list as the direct-access URI obtaining response &lt;D- 25 &gt; ( FIG. 11 : step S 1107 ), the XMPP server  43  of the direct-access management server  40  transmits, as a direct-access start response &lt;D- 26 &gt;, the direct-access URI list to the service server  30  ( FIG. 11 : step S 1111 ). 
   When the direct-access management server  40  receives, as the direct-access URI obtaining response &lt;D- 25 &gt;, the error code that gives an instruction for content acquirement using tunneling ( FIG. 11 : step S 1109 ), the direct-access management server  40  assigns a tunneling port in the direct-access management server  40  ( FIG. 11 : step S 1110 ), uses the port number of the assigned tunneling port in the direct-access management server  40  and the global IP address of the direct-access management server  40  to create a direct-access URI list, and transmits a direct-access start response &lt;D- 26 &gt; containing the direct-access URI list to the service server  30  ( FIG. 11 : step S 1111 ). 
   Since the service server  30  has obtained the direct-access URI for directly acquiring content from the DVR  20  through the processing described above, the service server  30  starts processing for acquiring the selected content from the DVR  20 . In this case, the direct-access URI list received by the service server  30  as the direct-access start response &lt;D- 26 &gt; contains a direct-access URI corresponding to each content selected by the user. 
   Upon receiving the direct-access start response &lt;D- 26 &gt; containing the direct-access URI list ( FIG. 18 : step S 1826 ), the service server  30  selects a direct-access URI corresponding to content on which acquiring processing is performed from the direct-access URI list and transmits a content acquiring request &lt;D- 27 &gt; containing the direct-access URI to the DVR  20  ( FIG. 18 : step S 1827 ). Upon receiving the content acquiring request &lt;D- 27 &gt; from the service server  30  ( FIG. 12 : step S 1218 ), the DVR  20  checks the validity of the direct-access URI contained in the content acquiring request &lt;D- 27 &gt; ( FIG. 12 : step S 1219 ). When the URI is invalid, the DVR  20  transmits, as a content acquiring response &lt;D- 27 R&gt;, an error code indicating that the URI is invalid to the service server  30  ( FIG. 12 : step S 1220 ). When the URI is valid, the DVR  20  transmits, as a content obtaining response &lt;D- 27 R&gt;, content specified by the direct-access URI to the service server  30  ( FIG. 12 : step S 1221 ). 
   Upon receiving the content from the DVR  20  as the content acquiring response &lt;D- 27 R&gt; ( FIG. 18 : step S 1828 ), the service server  30  transmits, as a content acquiring response &lt;D- 28 &gt;, the content to the mobile phone  10  ( FIG. 18 : step S 1829 ) and repeats the transmission of the content acquiring request &lt;D- 27 &gt; to the DVR  20  in step S 1827  until the acquirement of all the content contained in the direct-access URI list is completed ( FIG. 18 : step S 1830 ). Upon receiving the content acquiring response &lt;D- 28 &gt; ( FIG. 17 : step S 1727 ) containing the content, the mobile phone  10  displays the received content to the user via the display unit. 
   Also, when the service server  30  receives, as the content acquiring response &lt;D- 27 R&gt;, the error code indicating the URI is invalid from the DVR  20  ( FIG. 18 : step S 1831 ), the service server  30  transmits the error code to the mobile phone  10  as a content acquiring response &lt;D- 28 &gt; ( FIG. 18 : step S 1832 ). 
   As described above, the mobile phone  10  can acquire content from the DVR  20  by directly accessing the DVR  20  or by using proxy access performed by the service server  30 . The above description has been given of a case in which content acquiring service is a service that cannot be tunneled. However, the tunneling processing described for the remote video-recording reservation service may be applied to the content acquiring service, so that the tunneling processing via the XMPP server  43  of the direct-access management server  40  can be used in the content acquiring service to acquire content from the DVR  20 . 
   [5. Completion of Direct Access] 
   Next, a description will be given of processing in which the service server  30 , the direct-access management server  40 , and the DVR complete the direct access after the completion of the various types of processing described above.  FIG. 20  is a sequence diagram showing the flow of information when the direct access is completed.  FIG. 21  is a flow chart showing the operation of the service server  30  when the direct access is completed.  FIG. 22  is a flow chart showing the operation of the direct-access management server  40  when the direct access is completed.  FIG. 23  is a flow chart sowing the operation of the DVR  20  when the direct access is completed. 
   Upon receiving a direct-access completion notification &lt;C- 1 &gt; containing the user identification information from the mobile phone  10  ( FIG. 21 : step S 2101 ), the service server  30  transmits a direct-access completion notification &lt;C- 2 &gt; containing the service ID, the controlling-device/service management ID, the XMPP session ID, the service URN, and the direct-access URI to the direct-access management server  40  ( FIG. 21 : step S 2102 ). 
   Upon receiving the direct-access completion notification &lt;C- 2 &gt; ( FIG. 22 : step S 2201 ), the direct-access management server  40  transmits a direct-access completion notification &lt;C- 3 &gt; containing the service URN and the direct-access URI to the DVR  20  ( FIG. 22 : step S 2202 ). At this point, when the direct-access completion notification &lt;C- 2 &gt; does not designate a direct-access URI ( FIG. 22 : step S 2206 ), the direct-access management server  40  transmits a direct-access completion notification &lt;C- 3 &gt; containing only the service URN to the DVR  20  ( FIG. 22 : step S 2207 ). 
   Upon receiving the direct-access completion notification &lt;C- 3 &gt; containing the service URN and the direct-access URI ( FIG. 23 : step S 2301 ), the DVR  20  performs closing &lt;C- 4 &gt; of the direct-access port, including a global IP address and a port number related to the specified direct-access URI ( FIG. 23 : step S 2302 ). 
   On the other hand, after transmitting the direct-access completion notification &lt;C- 2 &gt;, the service server  30  initializes the mobile-device direct flag ( FIG. 21 : step S 2103 ). Next, the service server  30  transmits an XMPP logout notification &lt;C- 5 &gt; containing the service ID, the controlling-device/service management ID, and the XMPP session ID to the direct-access management server  40  ( FIG. 21 : step S 2104 ). Lastly, the service server  30  deletes the XMPP session ID entry ( FIG. 21 : step S 2105 ). 
   Upon receiving the XMPP logout notification &lt;C- 5 &gt; containing the service ID, the controlling-device/service management ID, and the XMPP session ID ( FIG. 22 : step S 2203 ), the direct-access management server  40  determines whether or not direct-access completion notifications for all service URNs related to the XMPP session ID have been issued to the DVR  20  ( FIG. 22 : step S 2204 ). When a service URN for which the direct-access completion notification is to be issued remains, the direct-access management server  40  transmits a direct access completion notification &lt;C- 3 &gt; that designates only the service URN but does not designate a direct-access URI to the DVR  20  ( FIG. 22 : step S 2205 ). Upon issuing all completion notifications, the direct-access management server  40  waits for the direct-access completion notification &lt;C- 2 &gt; from the service server  30 . 
   Upon receiving the direct-access completion notification &lt;C- 3 &gt; that does not designate a direct-access URI from the direct-access management server  40  ( FIG. 23 : step S 2303 ), the DVR  20  closes all ports related to the service URN specified by the direct-access completion notification &lt;C- 3 &gt; ( FIG. 23 : steps  2304  and S 2305 ). 
   Through the execution of the processing described above, the service server  30 , the direct-access management server  40 , and the DVR  20  complete the direct access. 
   A second embodiment of the present invention will be described next. 
   The description in the above embodiment has been given of a method in which the service server  30  obtains the controlled-device registration password, which is a one-time password, from the DAP direct-access management server  40  in response to a request from the mobile phone  10 . In this embodiment, however, the DVR  20  (the controlled device) may obtain the controlled-device registration password, which is a one-time password, from the direct-access management server  40 . 
   Although the configuration and the operation of the network system according to the embodiment of the present invention have been described above, some of the functions of the service server  30  can also be transferred to a controlling device. For example, making changes so that the function of the service server  30  for accessing the SOAP interface is included in a controlling device (the mobile phone  10 ) allows the direct-access use sequence, which starts by issuing the XMPP login request, to be executed directly between the controlling device (the mobile phone  10 ) and the direct-access management server  40 . 
   The functions of a controlling device and the functions of a controlled device can also be integrated into one unit. In this case, when the controlling device (the mobile phone  10 ) accesses an XMPP session with the controlled device (the DVR  20 ), the controlling device exchanges necessary information in a direct access manner without using the SOAP server  42  during the XMPP session. 
   In addition, direct access between controlled devices is also possible. In this case, the controlled devices are associated by a controlling device. 
   In the embodiment described above, the service server  30  is provided between the mobile phone  10 , which serves as a controlling device, and the direct-access management server  40 . Thus, the direct-access management server  40  stores a controlling-device/service management ID, generated so as to correspond to a combination of the mobile phone  10  and the service server  30 , in association with a controlled-device management ID. However, the present invention is not limited to the configuration. That is, the present invention can also be used in an environment where communication is directly performed between a controlling device and the direct-access management server  40  without the use of the service server  30 . In this case, instead of the controlling-device/service management ID generated in the embodiment described above, the direct-access management server  40  generates a controlling-device management ID for identifying a controlling device and stores the generated ID in association with a controlled-device management ID. The controlling-device management ID may be generated by the direct-access management server  40 . Alternatively, when a controlling device can make publicly available an ID that allows the identification of the controlling device, the ID given from the controlling device may be used as a controlling-device management ID to be associated with a controlled-device management ID. This also applies to a controlled-device management ID. That is, when a controlled device can make publicly available an ID that allows the identification of the controlled device, the ID given from the controlled device may be used as a controlled-device management ID to be associated with a controlling-device management ID. In addition, each of devices connected, as controlling devices and controlled devices, to the direct-access management server  40  may also has a unit for controlling another device and a unit to be controlled by another device. 
   Needless to say, the present invention is not limited to only the embodiment described above, and thus, various modifications can be made thereto in a scope without departing from the substance of the present invention. 
   The present invention can simplify the procedure after the completion of the device registration until the establishment of an always-on connection session with the server apparatus.