Patent Publication Number: US-2006004576-A1

Title: Server device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2004-192933, filed Jun. 30, 2004, the entire contents of which are incorporated herein by reference.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to contents management technology in digital versatile disk (DVD) recorders and the like.  
      2. Description of the Related Art  
      Remarkable improvements have recently been made in compressing and encoding technology and expanding and decoding technology and contents including moving images can be handled easily via a network (see, for example, Jpn. Pat. Appln. KOKAI Publication No. 2001-155022). Some users have a plurality of DVD recorders (server devices) connected to the same home network. For users&#39; operability, the server devices have a function of making the contents of all the server devices available using any one of the server devices as an entrance.  
      The above function is fulfilled if the entrance server device collects and manages the uniform resource locators (URL) of contents of the other server devices. In order to use the contents in a playback unit such as a personal computer via a network, a user has only to gain access to only a specific server device wherever the contents are located. The user&#39;s operability can thus be improved.  
      Some server devices do not transfer any contents without receiving a transfer-preparation request. More specifically, even though a user acquires the URL of a desired content from an entrance server device and traces another server device having the content based on the URL to request the transfer of the content, a transfer-preparation request has been transmitted to the entrance server device and thus it is not transmitted to the other server devices, with the result that the content is not transferred.  
      A server device that requires a transfer-preparation request generally requires a transfer-completion request when it completes transferring a content. Naturally, the transmission of this transfer-completion request is not taken into consideration and thus becomes impossible.  
     BRIEF SUMMARY OF THE INVENTION  
      According to an embodiment of the present invention, a server device that receives a request for contents from a playback unit connected to the server device via a network, comprises a database which stores related information of each of the contents, the related information including a location of each of the contents and causing the playback unit to select and acquire a desired content; a retrieving unit configured to retrieve another server device connected to the network; a registering unit configured to create related information of a content of a retrieved server device and to store the related information in the database, when the retrieving unit retrieves the another server device; and a relay unit configured to transmit a transfer-preparation request to the another server device, then acquires the content from the another server device, and transfers the content to the playback unit, when the content of the another server device is requested from the playback unit, wherein the registering unit determines whether or not the another server device requires the transfer-preparation request before the content is transferred, creates related information described a location of the content such that the another server device is directly traced and stores the related information in the database when the transfer-preparation request is not required, and creates related information described the location of the content such that the another server device is traced via the relay unit and stores the related information in the database when the transfer-preparation request is required.  
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
      The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention.  
       FIG. 1  is a block diagram of a home network system configured by a server device according to an embodiment of the present invention;  
       FIG. 2  is a block diagram of a home network system configured by a prior art server device;  
       FIG. 3  is a flowchart showing a first operating procedure of a registration and deletion unit of the server device according to the embodiment of the present invention;  
       FIG. 4  is a flowchart showing a second operating procedure of the registration and deletion unit of the server device according to the embodiment of the present invention; and  
       FIG. 5  is a flowchart showing an operating procedure of a relay unit of the server device according to the embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      An embodiment of the present will be described with reference to the accompanying drawings.  
       FIG. 1  is a block diagram of a home network system configured by a server device according to an embodiment of the present invention. Referring to  FIG. 1 , a first server  1 , a second server  2  and a playback unit  3  are connected via a channel  4  in the home network system. For easy understanding,  FIG. 1  shows one second server  2  and one playback unit  3 . However, two or more second servers  2  can be connected to the home network system, as can be two or more playback units  3 . The present embodiment is based on the premise that a universal plug and play (UPnP) Media Server, a UPnP Media Renderer and a UPnP control point are applied to the home network system.  
      The first server  1  is a server device according to the present embodiment and corresponds to the UPnP Media Server. The first server  1  includes a first database  11 , a first content  12 , a registration and deletion unit  13  and a relay unit  14 . The first database  11  and first content  12  are data sections configured on a storage medium of the first server  1 . The registration and deletion unit  13  and relay unit  14  are processing sections generated as a result of executing related programs by a processor of the first server  1 .  
      The first database  11  corresponds to UPnP Content Directory Service and stores a first database element  111  and a third database element  112 . The first database element  111  describes meta information about the first content  12  in the first server  1  itself. This meta information includes the URL of the content (“URL1” as the URL of the first content  1 ). The third database element  112  describes meta information about the second content  22  in the second server  2 . This meta information also includes a URL; however, this URL is not the URL of the second content  22  but a combination of the URL of the relay unit  14 , that of a control unit  23  in the second server  2  and that of the second content  22  (“URL4?server=URL3&amp;content=URL2”). The third database element  112  is created by the registration and deletion unit  13  in the steps described later.  
      The first content  12  is included in the first server  1  and can be read out by “URL1.” When the registration and deletion unit  13  detects on the channel  4  a server (second server  2 ) other than the server (first server  1 ) to which the unit  13  belongs, it fetches a database element (second database element  211 ) from the database (second database  21 ) of the detected server and stores it in the first database  11 . This stored database element is the third database element  112  descried above. The registration and deletion unit  13  allows the contents of two or more servers on the channel  4  to be read by the first database  11  in a unified way.  
      Assume in the present embodiment that the second server  2  requires a transfer-preparation request before its content is transferred. The registration and deletion unit  13  refers to a device description  24  (described later) of the second server  2  to recognize that the second server  2  requires the transfer-preparation request before its content is transferred, rewrite the URL of the second database element  211  as described above, and store it in the third database  112 . In other words, the third database element  112  stores a combination of “URL4” as the URL of the relay unit  14 , “URL3” as the URL of the control unit  23  of the second server  2  and “URL2” as the URL of the second content  22  in the form of URL 4 ?server=URL 3 &amp;content=URL 2 .  
      When the second server  2  does not require any transfer-preparation request, the registration and deletion unit  13  stores “URL2” in the third database element  112  as the URL of the second content  22 . When the second server  2  disappears from the channel  4 , the unit  13  deletes the database element from the first database  11 .  
      As a result of rewriting the URL of the database element to include the URL of the relay unit  14  itself as described above, if the relay unit  14  is required a content from the playback unit  3 , the relay unit  14  sends a transfer-preparation request to the control unit  23  of “URL3” that is included in the URL of the required content in the form of “URL4?server=URL3&amp;content=URL2.” Then, the relay unit  14  acquires the content by “URL2” and transfers it to the playback unit  3 . When the relay unit  14  completes transferring the content, it issues a transfer-completion request to the control unit  23  of “URL3.” 
      In order to clarify the differences between the server device of the present embodiment and the prior art server device,  FIG. 2  shows a home network system configured by the prior art server device. In the system shown in  FIG. 2 , the URL of the second content is stored in the third database element as it is though the second server requires a transfer-preparation request and a transfer-completion request. This system does not include any relay unit serving as an intermediate for acquiring the second content while transmitting a transfer-preparation request and a transfer-completion request to the second server.  
      Though the second server  2 , playback unit  3  and channel  4  of the present embodiment are the same as those of the prior art home network system, they will be described briefly below.  
      Like the first server  1 , the second server  2  corresponds to the UPnP Media Server and includes the second database  21 , second content  22 , control unit  23  and device description  24 .  
      The second database  21  corresponds to the UPnP Content Directory Service and stores the second database element  211 . Like the first database element  111  in the first server  1 , the second database element  211  describes meta information about the second content  22  in the second server  2  itself. This meta information includes the URL of the content (“URL2” as the URL of the second content  22 ). The second content  22  is included in the second server  2  and can be read by “URL2.” 
      The control unit  23  corresponds to, for example, a UPnP ConnectionManager Service and controls the transmission of contents from the second server  2 . Upon receiving a transfer-preparation request such as a UPnP PrepareForConnection Action, the control unit  23  prepares to transmit a content. After the content is transmitted, the control unit  23  receives a transfer-completion request such as a UPnP ConnectionComplete Action.  
      The device description  24  corresponds to, for example, a UPnP device description and a service description and describes information about the second server  2 . Referring to the device description  24 , a user can determine whether or not the second server  2  requires a transfer-preparation request prior to the transfer of a content.  
      The playback unit  3  corresponds to, for example, a Media Renderer and a control point, and fetches a content from a server and plays it back. Prior to this playback, the playback unit  3  fetches database elements  111  and  112  from the first database  11  in the first server  1  and presents them to a user. If the user selects one of the database elements, the playback unit  3  traces the URL of the selected one to acquire its content and play it back. The channel  4  connects each of the servers and the playback unit to transfer information and contents between them.  
      The operating principle of the server device according to the present embodiment will be described with reference to FIGS.  3  to  5 .  FIGS. 3 and 4  are flowcharts showing an operating procedure of the registration and deletion unit  13  in the first server  1 .  
      The registration and deletion unit  13  monitors another server device connected to the channel  4  at regular time intervals (step A 1 ). If the unit  13  detects a new server device (YES in step A 2 ), it registers the content of the detected server device (step A 3 ).  FIG. 4  shows a flow of this registration.  
      The registration and deletion unit  13  refers to the device description of the detected server device (step B 1 ) and determines whether or not the detected server device requires a transfer-preparation request based on the device description (step B 2 ). If the transfer-preparation request is required (YES in step B 2 ), the unit  13  rewrites the URL of the content to trace the content via the relay unit (step B 3 ) and stores the database element in the database (step B 4 ). If it is not required (NO in step B 2 ), the unit  13  stores the database element without modification in the database (step B 4 ).  
      If the unit  13  detects a server device that disappeared from the channel  4  (YES in step A 4 ), it deletes the database element of the content of the server device from the database (step SA 5 ).  
       FIG. 5  is a flowchart showing an operating procedure of the relay unit  14 .  
      When the relay unit  14  is requested a content from the playback unit, the relay unit  14  transmits a transfer-preparation request to a server device represented by the URL of the content (step C 1 ). After the transfer-preparation request is transmitted, the relay unit  14  acquires the requested content from the server device by the URL (step C 2 ) and transfers it to the playback unit (step C 3 ).  
      When the relay unit  14  completes acquiring the content from the server device and transferring it to the playback unit, it transmits a transfer-completion request to the server device (step C 4 ).  
      As described above, in the server device (first server  1 ) of the present embodiment, the registration and deletion unit  13  determines whether or not a transfer-preparation request is required when it stores a database element about the content of another server device (second server  2 ) connected to the channel  4 . If the transfer-preparation request is required, the unit  13  rewrites the URL of the content to trace the content via the relay unit  14 . The relay unit  14  serves as an intermediate for obtaining a desired content while transmitting a transfer-preparation request and a transfer-completion request to another server device. Consequently, the contents of another server device that requires a transfer-preparation request and a transfer-completion request can be used appropriately.  
      Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.