Abstract:
Provided is a network system having connected thereto (i) a plurality of television receivers each having a function for specifying television program reservations, and (ii) a recording device, such that a list of the program reservations configured by all of the television receivers can be viewed on one television receiver. The recording device produces a predefined common reservation code, and sequentially receives and records the program reservation instructions with the common reservation codes in memory. When a list of the reservations is requested by one television receiver, a program reservation instruction is sent from memory with the common reservation code, and a list of reservations is compiled based on the common reservation codes.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a system and a method for displaying recording reservations for broadcast television programs on a home network. 
     Home network systems in which a plurality of television receivers or a plurality of computers (reservation clients) are connected to a single recording device (recording server) are increasingly used in homes. An example of such a home network system is shown in  FIG. 1 . 
     In  FIG. 1  the recording device  1  is a recording server connected to television receivers X, Y, Z. Each of the television receivers X, Y, Z is a reservation client with a program recording reservation function. 
     Various methods of selecting the program to be recorded when programming a particular program for recording (“program selection method”) are known from the literature. These include the following four common types. 
     (1) Direct channel (direct manual) 
     (2) Direct CDS EPG 
     (3) Direct CDS NONEPG 
     (4) Direct program code 
     The first method, (1) direct channel (direct manual), uniquely specifies the program to be recorded by the recording client by specifying information that uniquely identifies the channel, such as the channel tuning number, the recording start time, and the recording time (how long recording is to continue). 
     When the recording server has a function for presenting electronic program guide (EPG) information based on the DLNA guidelines by program unit, the second method, (2) direct CDS EPG, can be used to uniquely specify the program to be recorded using the program identification information (CDS Item ID) of the desired program by causing the reservation client to search for the CDS Item ID of the desired program using the content search command (“CDS:Browse command” below) of the Content Directory Service (CDS), which is defined according to the DLNA (Digital Living Network Alliance) guidelines. 
     When the recording server has a function for presenting electronic program guide (EPG) information based on the DLNA guidelines by channel unit, the third method, (3) Direct CDS NONEPG, can be used to uniquely specify the program to be recorded by causing the reservation client to search for the virtual channel ID (CDS Item ID) of the broadcasting station that broadcasts the program to be recorded using the CDS:Browse command, and specifying the virtual channel ID (CDS Item ID), recording start time, and recording time. 
     When a third-party organization assigns a unique ID to each program and publishes these ID numbers in a newspaper, magazine, or other forum, the fourth method, (4) direct program code, can be used to uniquely identify the program to be recorded by the reservation client specifying the unique program ID number (Program Code) of the desired program. 
     In this example television receiver X has the first reservation function (1) described above, television receiver Y has reservation functions (1) and (2), and television receiver Z has reservation functions (1) and (3). The recording device enables programming recording reservations using methods (1), (2), and (3). 
     It is also assumed that the user has reserved recording a morning news program on television receiver X using method (1), has reserved recording a Japanese cooking program on television receiver Y using method (2), and has reserved recording a golfing lesson program on television receiver Z using method (3). Reservation information for these three programs is sent to and received by the recording device  1 . More specifically, the reservation clients, that is, television receivers X, Y, Z, send an SRS (Scheduled Recording Service) reservation command (SRS:CreateRecordSchedule) conforming to DLNA guidelines to the recording device  1  using a protocol defined in SOAP (Simple Object Access Protocol). As a response to the SRS reservation command, the recording device  1  sends a reservation ID and recording reservation completion information including recording address information to the corresponding reservation client, and executes the reserved recording when the reservation time arrives. 
     When the user tries to view a list of all recording reservations received by the recording device  1  on the screen of television receiver X, a list of all recording reservations can be seen by the television receiver X creating and sending an SRS reservation list acquisition command to the recording device  1  using the SOAP protocol, receiving a recording reservation list in response, and displaying the received recording reservation list. Normally, however, the program reservation information in the reservation list is returned in the form of the information that is specified in reservation methods (1), (2), and (3) above when the recording is programmed by television receivers X, Y, Z. Therefore, because television receiver X only has reservation function (1), only the program information that is reserved using reservation function (1) can be viewed. As a result, the recording reservation for the morning news show that was reserved by television receiver X can be confirmed, but the reservations for the Japanese cooking show and the golf lesson program cannot be confirmed ( FIG. 2A ). 
     Likewise, if the user tries to view a list of all recording reservations received by the recording device  1  on the screen of television receiver Y, only the information for the morning news show and the Japanese cooking program that were reserved using reservation functions (1) and (2) can be seen because television receiver Y only has recording reservation functions (1) and (2) ( FIG. 2B ). 
     Further likewise, if the user tries to view a list of all recording reservations received by the recording device  1  on the screen of television receiver Z, only the information for the morning news show and the golf lesson program that were reserved using reservation functions (1) and (3) can be seen because television receiver Z only has recording reservation functions (1) and (3) ( FIG. 2C ). 
     See, for example, Japanese Patent Publication No. JPA-2005-244372. 
     As described above, because the program selection methods that each reservation client can use or understand differ according to the model, a television receiver that is compatible only with particular program selection methods cannot view all of the reservation information issued by television receivers X, Y, Z that are compatible with different program selection methods. 
     SUMMARY OF THE INVENTION 
     The present invention therefore enables viewing on one television receiver all reservation information received by the recording device. 
     A first aspect of the invention is a network system having connected thereto a plurality of reservation devices each having a function for specifying television program reservations, and at least one recording device. The recording device has a common reservation code generator that generates predefined common reservation codes in response to program reservation instructions sent from the reservation devices, and memory for sequentially receiving and storing program reservation instructions together with the common reservation codes. Each of the reservation devices has a request output device that outputs a reservation list request, a reservation instruction receiver that receives all program reservation instructions including a common reservation code sent from the recording device based on the reservation list request, a reading device that reads only common reservation codes from the program reservation instructions, and a reservation list generator that generates a reservation list using common reservation codes. 
     A second aspect of the invention is a method of displaying a reservation list in a network system having connected thereto a plurality of reservation devices each having a function for specifying television program reservations, and at least one recording device, including in the recording device steps of generating predefined common reservation codes in response to program reservation instructions sent from the reservation devices, and sequentially receiving and storing program reservation instructions together with the common reservation codes; and including in each of the reservation devices steps of outputting a reservation list request, receiving all program reservation instructions including a common reservation code sent from the recording device based on the reservation list request, reading only common reservation codes from the program reservation instructions, and generating a reservation list using common reservation codes. 
     The reservation device may be any device with a reservation function, including, for example, television receivers, recording devices, cell phones, and personal computers. 
     Effect of the Invention 
     Because the recording device produces reservation information using a common reservation code in the invention, any television receiver (referred to as “the television receiver”) that is connected to the network and can read the common reservation codes can display a list of all programs that have been reserved, including programs that are reserved using a program selection method with which the television receiver is not compatible but with which another television receiver connected to the network is compatible. 
     Other objects and attainments together with a fuller understanding of the invention will become apparent and appreciated by referring to the following description and claims taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of a network system according to the related art. 
         FIG. 2A  is a sample screen display showing a list of recording reservations displayed on a television receiver according to the related art. 
         FIG. 2B  is a sample screen display showing a list of recording reservations displayed on another television receiver according to the related art. 
         FIG. 2C  is a sample screen display showing a list of recording reservations displayed on a yet another television receiver according to the related art. 
         FIG. 3  is a block diagram of a network system according to the invention. 
         FIG. 4A  is a sample screen display showing a list of recording reservations displayed on a television receiver according to the invention. 
         FIG. 4B  is a sample screen display showing a list of recording reservations displayed on another television receiver according to the invention. 
         FIG. 4C  is a sample screen display showing a list of recording reservations displayed on yet another television receiver according to the invention. 
         FIG. 5A  is a block diagram of the part of a television receiver according to the invention that is related to the recording reservation function. 
         FIG. 5B  is a block diagram of the part of another television receiver according to the invention that is related to the recording reservation function. 
         FIG. 5C  is a block diagram of the part of yet another television receiver according to the invention that is related to the recording reservation function. 
         FIG. 6  is a block diagram of a recording device according to the invention. 
         FIG. 7A  shows an example of a recording reservation information command from a television receiver  200 A. 
         FIG. 7B  shows an example of a recording reservation information command from a television receiver  200 A. 
         FIG. 7C  shows an example of a recording reservation information command from a television receiver  200 A. 
         FIG. 7D  shows an example of recording reservation list information. 
         FIG. 8  shows an example of a recording reservation list. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A system for displaying program recording reservations according to the present invention is used in a network system having a plurality of reservation clients connected to at least one reservation server. 
     The reservation server is a device with a function for recording video signals received from a tuner and signals input from an external input terminal, and is comparable to devices such as video decks, hard disk drive/DVD recorders, personal computers, cell phones, software programs, and other such constructions. 
     Embodiment 1 
       FIG. 3  shows a network system having a program recording reservation display system according to the invention. In  FIG. 3  reference numeral  100  denotes a recording device, and reference numerals  200 A,  200 B, and  200 C denote television receivers. When the television receivers are considered generically, they are denoted television receiver  200 . 
     Each of the television receivers  200 A,  200 B, and  200 C has at least one type of program recording reservation function. For example, in the embodiment described below, television receiver  200 A has a reservation function that uses program selection method (1) described above, television receiver  200 B has a reservation function that uses program selection methods (1) and (2) described above, and television receiver  200 C has a reservation function that uses program selection methods (1) and (3) described above. Note that these reservation functions are used by way of example only, and other reservation functions may be used. 
       FIG. 5A ,  FIG. 5B , and  FIG. 5C  show television receiver  200 A, television receiver  200 B, and television receiver  200 C, respectively, with a recording reservation device according to the invention. 
     Each of the television receivers  200 A,  200 B, and  200 C has an input/output port  20 , DLNA interpreter  21 , reservation list data extraction unit  22 , program identification information interpreter/generator  24 , tag detector  26 , common reservation code reader  28 , information assembler  30 , reservation list generator  32 , and operating unit  34 . 
     The operating unit  34  has, for example, a GUI screen drawing controller (not shown in the figure) and a remote control receiver (not shown in the figure) for the television receiver, draws an electronic program guide and program identification information input screen, sends program reservation operations from a remote control device for reserving a program selected from the electronic program guide to the program identification information interpreter/generator  24 , and instructs the program identification information interpreter/generator  24  to configure a program recording reservation based on program identification information (input information such as the channel number, recording start time, recording time, and recording image quality) input by the user. 
     Because television receiver  200 A is compatible only with program selection method (1), only a manual input reservation interpreter/generator  24   a  is rendered in the program identification information interpreter/generator  24 . 
     Because television receiver  200 B has two reservation functions, the (1) direct channel (direct manual) method and the (2) direct CDS EPG (DIRECT CDSEPG) method, both a manual input reservation interpreter/generator  24   a  and a CDS EPG input reservation interpreter/generator  25   b  are rendered in the program identification information interpreter/generator  24 . 
     Furthermore, because television receiver  200 C has two reservation functions, the (1) direct channel (direct manual) method and the (2) direct CDS NONEPG (DIRECT CDSNONEPG) method, both a manual input reservation interpreter/generator  24   a  and CDS NONEPG input reservation interpreter/generator  25   c  are rendered in the program identification information interpreter/generator  24 . 
     In the situation described below a recording reservation for the morning news show has been programmed by the user inputting the channel number of the station that broadcasts the desired morning news program, the date and time that the morning news program starts, and the broadcast time, that is, how long the morning news program is broadcast (referred to as the “program length”), by the operating unit  34 . The manual input reservation interpreter/generator  24   a  shown in  FIG. 5A  compiles reservation code data Ra(D 1 ) (SRS service compatible) based on the manually input data, and the DLNA interpreter  21  generates an SRS:CreateRecordSchedule command from the compiled reservation code data Ra(D 1 ) and sends the SRS:CreateRecordSchedule command through the I/O port  20  to the recording device  100 . 
     Based on the DLNA guidelines, the television receiver  200 B acquires the electronic program guide information from the recording device  100  using the CDS:Browse command, and displays the EPG information as an electronic program listing on the operating unit  34 . When the user selects and programs recording the Japanese cooking program, for example, using the electronic program guide displayed by the operating unit  34 , the program identification information (CDS Item ID) for the selected show is extracted from the CDS:Browse command response and passed to the CDS EPG input reservation interpreter/generator  24   b  shown in  FIG. 5B . The CDS EPG input reservation interpreter/generator  24   b  compiles reservation code data Rb(D 1 ) based on the program identification information (CDS Item ID), and the DLNA interpreter  21  generates an SRS:CreateRecordSchedule command from the compiled reservation code data Rb(D 1 ) and sends the SRS:CreateRecordSchedule command through the I/O port  20  to the recording device  100 . 
     Based on the DLNA guidelines, the television receiver  200 C then acquires the electronic program guide information from the recording device  100  using the CDS:Browse command, and displays the channel information acquired by the operating unit  34  as a channel listing. When the user selects the channel on which the golf lesson program is broadcast from the channel list presented by the operating unit  34  and enters a recording reservation for the broadcasting time, the virtual channel ID (CDS Item ID) of that channel is executed from the response to the CDS:Browse command and passed together with the broadcast time information to the CDS NON EPG input reservation interpreter/generator  24   c  shown in  FIG. 5C . The CDS NONEPG input reservation interpreter/generator  24   c  then compiles reservation code data Rc(D 1 ) based on the CDS NONEPG input from the virtual channel ID (CDS Item ID) and broadcast time, and the compiled reservation code data Rc(D 1 ) is sent as the SRS:CreateRecordSchedule command through the I/O port  20  to the recording device  100  by the DLNA interpreter  21 . 
       FIG. 7A ,  FIG. 7B , and  FIG. 7C  respectively show examples of the recording reservation information compiled as XML document objects (SRS Document) in the SRS:CreateRecordSchedule command when the recordings were reserved by television receivers  200 A,  200 B, and  200 C. 
       FIG. 7A  shows the recording reservation information  701  that is compiled in television receiver  200 A. The recording reservation information  701  is the recording reservation information for the morning news program indicated by the reservation code data Ra(D 1 ) shown in  FIG. 5A . As described above, because reservations by the television receiver  200 A are based on the direct channel (direct manual) method (1), the program scheduled for recording (the “recording reservation program”) is identified by an information object  704  combining information (class element) indicating that the program selection method (1) was used, information (scheduledChannelID element) identifying the channel, the recording start time (scheduledStartDateTime element), and the recording time (scheduledDuration element). 
       FIG. 7B  shows the recording reservation information  702  that is compiled in television receiver  200 B. The recording reservation information  702  is the recording reservation information for the Japanese cooking program indicated by the reservation code data Rb(D 1 ) shown in  FIG. 5B . As described above, because reservations by the television receiver  200 B are based on the direct CDS EPG (DIRECT CDSEPG) method (2), the recording reservation program is identified by an information object  705  combining information (class element) indicating that program selection method (2) was used, and the program identification information (CDS Item ID) (scheduledCDSObjectID element) assigned to each program by the recording device  100 , which is a DLNA server. Note that the program identification information (CDS Item ID) is acquired by the television receiver  200 B, that is, the DLNA client, searching for the program as the DLNA content. 
       FIG. 7C  shows the recording reservation information  703  that is compiled in television receiver  200 C. The recording reservation information  703  is the recording reservation information for the golf lesson program indicated by the reservation code data Rc(D 1 ) shown in  FIG. 5C . As described above, because reservations by the television receiver  200 C are based on the direct CDS NONEPG (DIRECT CDSNONEPG) method (3), the recording reservation program is identified by an information object  706  combining information (class element) indicating that program selection method (3) was used, the virtual channel ID (CDS Item ID) (scheduledCDSObjectID element) that is assigned to each channel by the recording device  100 , which is a DLNA server, the recording start time (scheduledStartDateTime element), and the recording time (scheduledDuration element). Note that the virtual channel ID (CDS Item ID) is acquired by the television receiver  200 C, that is, the DLNA client, searching for the channel as DLNA content. 
       FIG. 6  shows a recording device  100  that has a recording reservation device according to the invention. The recording device  100  has an input/output (I/O) port  2 , a DLNA interpreter  4 , a program identification information interpreter/converter  6 , a common reservation code generator  8 , a common reservation tag inserter  10 , reservation queue memory  12 , a timer  14 , and a recorder  16 . 
     Note that in the example described below a recording reservation for the morning news program is set on television receiver  200 A, a recording reservation for the Japanese cooking program is set on television receiver  200 B, and then a reservation for the golf lesson program is set on television receiver  200 C. 
     The DLNA interpreter  4  interprets the SOAP command received through the I/O port  2 , and outputs the result to the program identification information interpreter/converter  6  or reservation queue memory  12 . For example, if reservation code data Rc(D 1 ) is received by the SRS:CreateRecordSchedule command from the television receiver  200 C, the reservation code data Rc(D 1 ) is extracted from the SRS:CreateRecordSchedule command and the extracted reservation code data Rc(D 1 ) is output to the program identification information interpreter/converter  6 . For example, if the reservation list acquisition command SRS:BrowseRecordSchedules is received from the television receiver  200 C, a reservation list data acquisition command is output to the reservation queue memory  12 . 
     The program identification information interpreter/converter  6  interprets the reservation code data Rc(D 1 ) to extract the program identification information, converts the program identification information to tuner information and recording timer information for the recording device  100 , and stores the tuner information and recording timer information in the reservation queue memory  12 . Note that various interpreting units are rendered in the program identification information interpreter/converter  6 . In the example shown in  FIG. 6 , the program identification information interpreter/converter  6  has four interpreting units, that is, a manual input reservation interpreter  6   a , a CDS EPG input reservation interpreter  6   b , a CDS NONEPG input reservation interpreter  6   c , and a program code input reservation interpreter  6   d.    
     Because the reservation code data Rc(D 1 ) was generated based on the direct CDS NONEPG (DIRECT CDSNONEPG) method (3), the reservation code data Rc(D 1 ) is interpreted by the CDS NONEPG input reservation interpreter  6   c . An appropriate identification code or flag is set in the reservation code data Rc(D 1 ) so that the method used to program the reservation can be identified. 
     The CDS NONEPG input reservation interpreter  6   c  of the program identification information interpreter/converter  6  compiles data including the tuner information, which is the original data, and data related to the reservation code data converted to recording timer information as reservation code data Rc(D 1 , D 2 ). Note that (D 1 ) is a program identifier ID used in program selection method (3), and (D 2 ) is the recording reservation information required for the recording device  100  to actually start recording after conversion and includes such recording parameters as tuner information, recording timer information, and image quality setting. Parameter D 1 , which is the program identification information that is specified when a reservation is made by television receiver  200 C, which is a reservation client, and the recording reservation information parameter D 2  after conversion, are both added to the reservation code data Rc(D 1 , D 2 ). 
     The common reservation code generator  8  converts the interpreted/converted recording reservation information to a common reservation code, and produces common reservation code D 3 . The common reservation code D 3  may use the program identifier ID output by any single method used by the interpreters  6   a  to  6   d , such as program selection method (1) that specifies the program using the channel number, recording start date/time, and recording time, or a code output by a method other than those used by interpreters  6   a  to  6   d  may be used. The reservation code converted to a common reservation code is denoted by parameter D 3 . Service information SI including an identifier for identifying the broadcast channel (network_id, transport_id, service_id), and an identifier (event_id) for identifying the program, are set as the common reservation code. 
     The common reservation tag inserter  10  adds a common reservation tag to the common reservation code generated by the common reservation code generator  8 , that is, parameter D 3 . An identification flag or identification mark such as the identifier ID may be added instead of a common reservation tag. The reservation code data including the common reservation tag is denoted Rc(D 1 , D 2 , D 3 ). Note that one or both of parameters D 1  and D 2  may be omitted from the reservation code data output from the common reservation tag inserter  10 . 
     The reservation code data received from the television receivers  200 A,  200 B, and  200 C is stored sequentially in the reservation queue memory  12 . Note that in the example described below reservation code data Ra(D 1 , D 2 , D 3 ) and Rb(D 1 , D 2 , D 3 ) are already recorded, and a third reservation described by reservation code data Rc(D 1 , D 2 , D 3 ) is then added. Parameters D 1 , D 2 , and D 3  are parameters with different formats, but each is a parameter including at least such information as the reservation channel, the reservation start time, and the reservation end time (or program duration information). 
     The timer  14  checks the recording start date/time in parameter D 2  of each reservation code data entry recorded in the reservation queue memory  12 . When the time kept by the timer  14  reaches the recording start date/time in any reservation code data Ra, Rb, Rc entry, the channel number, recording time, and recording parameters are sent to the recorder  16  based on the information in parameter D 2 , and recording the program starts through a tuning and receiving means (not shown in the figure) such as the tuner of the recording device  100 . 
     An operation whereby a reservation list is produced using all reservation information is described next. An operation for viewing all reservation information on television receiver  200 C is described first. 
     A reservation list data request for compiling a reservation list is output by the operating unit  34  shown in  FIG. 5C . More specifically, the SRS:BrowseRecordSchedules command, which is a reservation list acquisition command, is sent to the recording device  100 . This request is sent through the DLNA interpreter  4  and I/O ports  20  and  2  to the reservation queue memory  12  ( FIG. 6 ). The method of the related art returns only parameter D 1  from each reservation code data entry as the response to the reservation list acquisition command. In this embodiment of the invention, however, each of the parameters D 1 , D 2 , D 3  is sent from all reservation code data entries Ra(D 1 , D 2 , D 3 ), Rb(D 1 , D 2 , D 3 ), and Rc(D 1 , D 2 , D 3 ) retrieved from the reservation queue memory  12  as the response to the reservation list acquisition command. 
       FIG. 7D  shows an example of the recording reservation list information in the SRS:BrowseRecordSchedules response sent from the recording device  100  as the response to the reservation list acquisition command. A common reservation code  708  (equivalent to parameter D 3 ) is included in the recording reservation list document  707 . Program identification information  704  to  706  (equivalent to parameter D 1 ) is included in the recording reservation list document  707  in addition to the common reservation codes  708 . 
     Note, also, that in addition to the programs reserved for recording by the television receivers  200 A,  200 B, and  200 C, programs reserved for recording by the recording device  100  may also be included in the recording reservation list document  707 . Because reservations programmed on the recording device  100  are not based on the SRS:CreateRecordSchedule command, they are managed using only the information contained in the common reservation code  708  or as a reservation set by directly specifying the channel, and are thus a combination of the common reservation code  708  and information with the same format as program identification information  704 . 
     The response is sent through I/O ports  2  and  20  and the DLNA interpreter  21  to the reservation list data extraction unit  22 . The reservation list data extraction unit  22  extracts reservation code data parameters D 1  and D 3 , which contain the reservation list data, from the response packets to the reservation list acquisition request command (SRS:BrowseRecordSchedules). The tag detector  26  detects the common program identification information tags in the extracted parameter D 3 . The common reservation code reader  28  reads the common program identifier ID that is identified by the detected common reservation tags. As a result, the reservation code group Ra (D 3 ), Rb (D 3 ), Rc (D 3 ) denoted by parameter D 3  only in the common reservation code is output from the common reservation code reader  28 . 
     The information assembler  30  assembles the data required for the reservation list using parameter D 3  of the common reservation code in the reservation code group. 
     The reservation list generator  32  produces and displays a list of all reservations on screen ( FIG. 4C ). As shown in  FIG. 4C , when the reservation list is viewed on television receiver  200 C, all of the programs that were reserved by television receiver  200 A and television receiver  200 B, including programs that are reserved using reservation functions that are not available on television receiver  200 C, can be viewed in addition to the programs (a golf lesson show in this example) that were reserved on the television receiver  200 C. More specifically, because the reservation list is produced using parameter D 3  of the common reservation code, all recording reservations can be viewed regardless of the television receiver  200  and regardless of the reservation method used to program the recordings. 
       FIG. 8  shows an example of a recording reservation list. The recording reservation list includes shows that are reserved by the recording device  100  for recording, such as “Drama at 2:00” in this example, instead of displaying only the programs for which recording reservations are programmed by the television receivers. Note, further, that programs reserved for recording may be indicated by highlighting  801  in the case of normal recording reservations, and by reverse highlighting  802  in the case of automatic recording reservations. A normal recording reservation as used herein refers to programs for which recording reservations are programmed individually, and an automatic recording reservation refers to recording reservations that are programmed once to record one segment of an on-going series, such as Star Trek, with the ensuing segments then automatically programmed for recording. Automatic recording reservations can also be programmed based on the user&#39;s viewing history. 
     Note, also, that automatic recording reservation programs may be omitted from the displayed recording reservation list even if the recording reservation information is received as a SOAP response, for example. 
     If automatic recording reservations and normal recording reservations are prioritized on the recording device  100 , whether recording is possible may be determined based on the available recording capacity of the recording device  100  when a recording reservation command for an automatic recording reservation program is received, for example. 
     Furthermore, when an automatic recording reservation is programmed, a normal recording reservation is then added by the user, and at least part of the recording times of the automatic recording reservation and the normal recording reservation overlap or there is not enough recording capacity to complete the recordings, the normal recording reservation may be given priority and the recording time of the automatic recording reservation may be shortened, for example. 
     Further alternatively, when the available recording capacity becomes insufficient, automatic recording reservation programs may be deleted or automatically recorded programs that have been left unseen for a long time may be automatically deleted. 
     Note that the reservation operation is described above using a television receiver by way of example, but devices other than television receivers, such as recording devices, cell phones, personal computers, and other devices connected to the network can also execute the reservation operation. Devices that can execute the reservation operation are “reservation devices.” 
     Note, further, that the reservation list data can also be viewed using the method of the related art on the television receiver  200 C. In this situation, when the display mode of the reservation list data is changed to the conventional mode, the data from the reservation list data extraction unit  22  is sent to the program identification information interpreter/generator  24 , and only the reservation list data corresponding to existing reservation functions can be seen. In this case only programs that are reserved by functions corresponding to the reservation functions of the television receiver  200 C appear in the reservation list. 
     An operation for viewing all reservation information on the television receiver  200 C is described above. By executing the same process on television receiver  200 A and television receiver  200 B, however, all reservation lists from television receiver  200 A to television receiver  200 C can be compiled and displayed (see  FIG. 4A  and  FIG. 4B ). 
     In this embodiment of the invention the recording device  100  sends a common reservation code to the television receiver  200 A to  200 C as the response to reservation list acquisition command. Alternatively, however, the common reservation code generator  8  may generate a DLNA public ID and send the DLNA public ID with the common reservation code as the response. By sending the CDS:Browse command, which is a CDS (Content Delivery Service)-standard information acquisition command for acquiring content information (DIDL: Digital Item Declaration Language) corresponding to the DLNA public ID, to the recording device  100 , the television receiver  200 A to  200 C in this case can acquire the content information and URL for the content in response. As a result, the reservation completion status can be checked based on the acquired content information and URL. For example, it can be determined that recording failed if the response to the CDS service acquisition command is an error, and it can be determined that recording failed if the recording time in the content information is short. 
     Furthermore, the television receivers  200 A to  2000  may store past electronic program guide information for a specified period of time, and the DLNA public ID may be additionally displayed when past electronic program guide information is displayed. 
     Alternatively, whether or not recording is possible may be determined using a CDS service acquisition command, and the result of determining whether recording was a success or failure may be displayed in the past electronic program guide information instead of displaying the DLNA public ID. As a result, recorded programs can be reproduced easily using only the electronic program guide. 
     Application In Industry 
     The present invention can be used in a network system interconnecting a plurality of television receivers and at least one recording device. 
     The invention being thus described, it will be obvious that it may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.