Patent Publication Number: US-2007106723-A1

Title: Information processing apparatus, data displaying method, information processing system and computer readable recording medium recorded thereon the data displaying program

Description:
TECHNICAL FIELD  
      The present invention relates to a technique for displaying data on a displaying unit connected to an information processing apparatus in an information processing system in which a data retaining apparatus (server) keeping data (for example, contents data) and the information processing apparatus executing a process on the data kept in the data retaining apparatus are connected over a network.  
     BACKGROUND ART  
      There has been a system in which an equipment functioning as a client among a plurality of equipments (for example, personal computers, recording/regenerating devices, portable recording/regenerating devices, recording devices, portable recording devices) connected over a network performs processes such as recording/regenerating and the like on not only data (for example, contents data of media contents) kept in itself but also data (hereinafter, referred to as contents data) kept in another equipment on the network. Incidentally, another equipment (data retaining apparatus) keeping data on the network will be hereinafter referred to as a server.  
      In such a system, an information processing apparatus (hereinafter, referred to simply as a client) operating as a client retrieves contents data from a server on the network on the basis of an application program (hereinafter, referred to simply as an application) executing a process on the contents data, displays a contents name or the like of the retrieved contents data on a display unit (monitor or the like) connected to this information processing apparatus, and executes a process such as regeneration or the like.  
      Incidentally, the client retrieves contents data from a server connected to the network by executing multi-casting on the basis of an extension discriminating an attribute of the contents data, for example, and makes a list of contents information such as a contents name, an attribute and so forth of the retrieved contents data.  
      The client executes a process on the contents data, using the listed contents information.  
      There have been a technique which establishes a communication with a terminal inside a LAN from the outside by using the Internet communication (refer to Patent Document 1 below, for example), and a technique which transfers contents among a plurality of nodes connected over a network to distribute and place plural sorts of contents in each node (refer to Patent Document 2 below, for example).  
      In the above-mentioned known system, the client retrieves and lists contents data distributed on the network each time an application executing a process on the contents data is activated.  
      For this, there may occur a case where, depending on the activation state of the server, for example, when the power source of the server connected to the network is in the OFF state, or when the server is in the stand-by state, or when the server is physically disconnected from the network, contents data kept in this server is not listed because the contents data kept in the server is not retrieved although the clients accessed to the contents data kept in the server in the past, and, as a result, a contents name and the like, which is data identification information of the contents data, are not displayed on the display unit.  
      Another case is that when the activation state of the server changes and the server becomes absent from the network while the application executing a process on the contents data is activated, contents information relating to the contents data kept in this server is deleted from the list, and is not displayed on the display unit.  
      As this, the known system has a disadvantage that contents data that should exist may abruptly disappear for a user (operator) operating the client because the contents data is not displayed on the display unit connected to the client depending on the activation state of the server keeping the contents data although the contents data was accessed in the past.  
      In order to restore the activation state of the server, the user has to go up to the server and restore the activation state of the server. Further, the contents kept in the server cannot be displayed unless the client is re-activated and the contents data is retrieved and listed, which is troublesome for the user.  
      In the light of the above problems, an object of the present invention is to make it possible to display, with certainty, data identification information about data that was retrieved in the past irrespective of the activation state of a data retaining apparatus keeping the data, and readily discriminate whether the data of the displayed data identification information is usable or not.  
      Patent Document 1: Japanese Patent Application Laid-Open No. 2003-169075  
      Patent Document 2: Japanese Patent Application Laid-Open No. 2003-216521  
     DISCLOSURE OF THE INVENTION  
      To attain the above object, an information processing apparatus according to this invention is an information processing apparatus connected to at least one data retaining apparatus over a network to execute a process on data kept in said data retaining apparatus, which comprises a data information obtaining unit obtaining data information relating to the data kept in the data retaining apparatus, a data list keeping unit keeping data identification information about the data and a retaining place in which the data is kept as a data list on the basis of the data information obtained by the data information obtaining unit, a data retaining apparatus monitoring unit monitoring whether the data retaining apparatus is accessible or not on the basis of data retaining apparatus information relating to the data retaining apparatus connected to said network, and a display controlling unit displaying the data identification information registered in the data list together with information representing whether the data of the data identification information is accessible or not on a displaying unit on the basis of the data list kept by the data list keeping unit and a situation of the monitoring by the data retaining apparatus monitoring unit.  
      Incidentally, it is preferable that the data list is based on data information obtained last by the data information obtaining unit in order to display the data information on the displaying unit by the display controlling unit.  
      It is preferable that the data retaining apparatus monitoring unit detects a change in connection state of the data retaining apparatus to the network to monitor whether the data retaining apparatus is accessible or not. At this time, it is preferable that the data retaining apparatus monitoring unit detects the change in connection state of the data retaining apparatus to the network on the basis of activation/stop information transmitted from the data retaining apparatus.  
      Further, it is preferable that the display controlling unit displays a data retaining apparatus name of the data retaining apparatus in which the data of the data identification information is kept together with the data identification information on the displaying unit.  
      It is preferable that the information processing apparatus further comprises a data selecting unit selecting data to be processed on the basis of the data list, and an activating unit activating said data retaining apparatus which keeps the data selected by the data selecting unit, when the situation of the monitoring of the data retaining apparatus by the data retaining apparatus monitoring unit is inaccessible.  
      To attain the above object, a data displaying method according to this invention is a data displaying method in an information processing apparatus connected to at least one data retaining apparatus over a network to execute a process on data kept in the data retaining apparatus, the data displaying method for displaying the data on a displaying unit equipped to said information processing apparatus comprises the steps of a data information obtaining step obtaining data information relating to the data kept in the data retaining apparatus, a data list keeping step keeping data identification information of the data and a retaining place in which the data is kept as a data list on the basis of the data information obtained at the data information obtaining step, a data retaining apparatus monitoring step monitoring whether the data retaining apparatus is accessible or not on the basis of data retaining apparatus information relating to the data retaining apparatus connected to the network, and a display controlling step displaying, on the displaying unit, the data identification information registered in the data list together with information representing whether the data of the data identification information is accessible or not on the basis of the data list kept at the data list keeping step and a situation of the monitoring at the data retaining apparatus monitoring step.  
      It is preferable that the data list is based on data information obtained last at the data information obtaining step in order to display the data information on the displaying unit at the display controlling step.  
      It is preferable that, at the data retaining apparatus monitoring step, a change in connection state of the data retaining apparatus to the network is detected to monitor whether the data retaining apparatus is accessible or not. At this time, it is preferable that, at the data retaining apparatus monitoring step, the change in connection state of the data retaining apparatus to the network is detected on the basis of activation/stop information transmitted from the data retaining apparatus.  
      It is preferable that, at the display controlling step, a data retaining apparatus name of the data retaining apparatus in which the data of the data identification information is kept is displayed together with the data identification information on the displaying unit.  
      It is preferable that the data displaying method further comprises the steps of a data selecting step selecting data to be processed on the basis of the data list, and an activating step activating said data retaining apparatus which keeps the data selected at the data selecting step, when the situation of the monitoring at the data retaining apparatus monitoring step of the data retaining apparatus is inaccessible.  
      To attain the above object, an information processing system according to this invention is an information processing system in which at least one data retaining apparatus and an information processing apparatus executing a process on data kept in the data retaining apparatus are connected over a network, which comprises a data information obtaining unit obtaining data information relating to the data kept in the data retaining apparatus, a data list keeping unit keeping data identification information about the data and a retaining place in which the data is kept as a data list on the basis of the data information obtained by the data information obtaining unit, a data retaining apparatus monitoring unit monitoring whether the data retaining apparatus is accessible or not on the basis of data retaining apparatus information relating to the data retaining apparatus connected to the network, and a display controlling unit displaying the data identification information registered in the data list together with information representing whether the data of the data identification information is accessible or not on a displaying unit connected to the information processing apparatus on the basis of the data list kept by the data list keeping unit and a situation of the monitoring by the data retaining apparatus monitoring unit.  
      It is preferable that the data list is based on data information obtained last by the data information obtaining unit in order to display the data information on the displaying unit by the display controlling unit. At this time, it is preferable that the data retaining apparatus monitoring unit detects a change in connection state of the data retaining apparatus to the network to monitor whether the data retaining apparatus is accessible or not.  
      Further, it is preferable that the data retaining apparatus comprises an activation notifying unit notifying the data retaining apparatus monitoring unit of activation/stop information representing an activation state of the data retaining apparatus itself, and the data retaining apparatus monitoring unit detects the change in connection state of the data retaining apparatus to the network on the basis of the activation/stop information transmitted from the activation notifying unit of the data retaining apparatus.  
      It is preferable that the display controlling unit displays a data retaining apparatus name of the data retaining apparatus in which the data of the data identification information is kept together with the data identification information on the displaying unit.  
      It is preferable that the information processing system further comprises a data selecting unit selecting data to be processed on the basis of the data list, and an activating unit activating the data retaining apparatus which keeps the data selected by the data selecting unit, when the a situation of the monitoring of the data retaining apparatus by the data retaining apparatus monitoring unit is inaccessible.  
      To attain the above object, a data displaying program according to this invention is a data displaying program for making a computer realize a function of displaying data on a displaying unit connected to an information processing apparatus in an information processing system in which at least one data retaining apparatus and the information processing apparatus executing a process on the data kept in the data retaining apparatus are connected over a network, the computer program making the computer function as a data information obtaining unit obtaining data information relating to the data kept in the data retaining apparatus, a data list keeping unit keeping data identification information about the data and a retaining place in which the data is kept as a data list on the basis of the data information obtained by the data information obtaining unit, a data retaining apparatus monitoring unit monitoring whether the data retaining apparatus is accessible or not on the basis of data retaining apparatus information relating to the data retaining apparatus connected to the network, and a display controlling unit displaying the data identification information registered in the data list together with information representing whether the data of the data identification information is accessible or not on a displaying unit on the basis of the data list kept by the data list keeping unit and a situation of the monitoring by the data retaining apparatus monitoring unit.  
      To attain the above object, a computer readable recording medium according to this invention is recorded thereon the above data displaying program.  
      According to this invention, on the displaying unit, displayed are data identification information registered in a data list on the basis of a data list including the data identification information of data and a retaining place in which the data is kept, and a situation of monitoring by the data retaining apparatus monitoring unit whether the data retaining apparatus is accessible or not, and information representing whether the data of the data identification information is accessible or not on the basis of a situation of the monitoring of the data retaining apparatus keeping the data of the data identification information by the data retaining apparatus monitoring unit. For this, even when the data retaining apparatus keeping the data is inaccessible, it is possible to display, with certainty, the data on the displaying unit. Namely, it is possible to display data registered in the data list, which was accessed in the past, irrespective of the activation state of the data retaining apparatus.  
      Information representing whether data of data identification information is displayed together with the data identification information on the displaying unit, whereby the user can discriminate, at a glance, whether the data displayed on the displaying unit is usable or not. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  Block diagram showing a structure of an information processing system according to an embodiment of this invention;  
       FIG. 2  Diagram showing a server list kept by a server list keeping unit in the information processing system according to the embodiment of this invention;  
       FIG. 3  Flowchart for illustrating a procedure for monitoring by a server monitoring unit in the information processing system according to the embodiment of this invention;  
       FIG. 4  Flowchart for illustrating a procedure for monitoring by the server monitoring unit in the information processing system according to the embodiment of this invention;  
       FIG. 5  Flowchart for illustrating a procedure for monitoring by the server monitoring unit in the information processing system according to the embodiment of this invention;  
       FIG. 6  Flowchart for illustrating a procedure for monitoring by the server monitoring unit in the information processing system according to the embodiment of this invention;  
       FIG. 7  Schematic diagram showing an example of display of contents on a displaying unit in the information processing system according to the embodiment of this invention;  
       FIG. 8  Schematic diagram showing an example of the display of the contents on the displaying unit in the information processing system according to the embodiment of this invention;  
       FIG. 9  Flowchart for illustrating a procedure for restoring a server to an active state by an activating unit in the information processing system according to the embodiment of this invention;  
       FIG. 10  Flowchart for illustrating a procedure for initial setting in the information processing system according to the embodiment of this invention;  
       FIG. 11  Flowchart for illustrating a procedure for a data displaying method according to the embodiment of this invention;  
       FIG. 12  Block diagram showing a structure of an information processing system according to a modification of this invention;  
       FIG. 13  Schematic diagram showing an example of display of contents on a displaying unit of the information processing system in  FIG. 12  according to the modification of this invention;  
       FIG. 14  Block diagram showing a structure of an information processing system according to a modification of this invention;  
       FIG. 15  Block diagram showing a structure of an information processing system according to a modification of this invention;  
       FIG. 16  Schematic diagram showing an example of display of a server on the displaying unit in the information processing system according to the embodiment of this invention; and  
       FIG. 17  Schematic diagram showing an example of display on the displaying unit displayed when the activating unit of the information processing system is executed according to the embodiment of this invention. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION  
      Hereinafter, description will be made of an embodiment of the invention with reference to the drawings.  
      [1] As to an Embodiment of the Invention  
      First, description will be made of an information processing system (information processing apparatus) according to an embodiment of this invention.  FIG. 1  is a block diagram showing a structure of an information processing system  100  according to an embodiment of this invention.  
      As shown in  FIG. 1 , in the information processing system  100 , an equipment (hereinafter, referred to as a server)  20  as being a data retaining apparatus, which keeps data (for example, contents data such as media contents or the like) and an information processing apparatus  30  operating as a client are connected over a network  10 .  
      The sever  20  is, for example, a personal computer, a recording/regenerating apparatus, a portable recording/regenerating apparatus, a recording apparatus, or a portable recording apparatus, which keeps data (hereinafter, referred to as contents data). The server  20  comprises, at least, a contents data keeping unit (data keeping unit)  21 , a power source controlling unit  22  and an activation state notifying unit  23 .  
      The contents data keeping unit  21  keeps contents data.  
      The power source controlling unit  22  controls a power source state or an activation state of itself (that is, the server  20 ). The power source controlling unit  22  activates the power source to the ON state according to an activate instruction (MP: Magic Packet) from an activating unit  72  to be described later.  
      The activation state notifying unit  23  notifies another equipment (here, the information processing apparatus  30 ) connected to the network  10  of activation/stop information representing the activation state of itself.  
      Namely, the activation state notifying unit  23  notifies another equipment on the network  10  that itself is activated when the power source of itself is activated to the ON state, and notifies another equipment on the network  10  that itself is stopped when the power source of itself is switched to the OFF state or to the stand-by state, for example.  
      The activation state notifying unit  23  responds to an inquiry from another equipment (here, a power source state confirming unit  55  of the information processing apparatus  30  to be described later), and sends the activation information when itself is active.  
      The information processing apparatus  30  as being a client executes a process on contents data kept by the server  20 . The information processing apparatus  30  comprises a contents information obtaining unit (data information obtaining unit)  40 , a contents list updating unit (data list updating unit)  41 , a contents list keeping unit (data list keeping unit)  42 , a server information obtaining unit (data retaining apparatus information obtaining unit)  50 , a server list updating unit (data retaining apparatus list updating unit)  51 , a server list keeping unit (data retaining apparatus list keeping unit)  52 , a server monitoring unit (data retaining apparatus monitoring unit)  53 , a displaying unit  60 , a display controlling unit  61 , a contents selecting unit (data selecting unit)  70 , a contents processing unit (data processing unit)  71  and the activating unit  72 .  
      The contents information obtaining unit  40  obtains contents information (data information) such as a contents name (data identification information) an attribute, a retaining place and so forth relating to contents data (for example, data of media contents) kept in the contents data keeping unit  21  in the server  20 .  
      The contents list updating unit  41  makes a contents list (data list) on the basis of the contents information obtained by the contents information obtaining unit  40 , and updates the contents list each time the contents information obtaining unit  40  newly obtains the contents information.  
      The contents list keeping unit  42  keeps the contents list made and updated by the contents updating unit  41  on the basis of the contents information obtained by the contents information obtaining unit  40 .  
      Here, the contents list includes, at least, a contents name and a retaining place [for example, a server name (server ID; Identification) ] at which contents data of this contents name is kept as the data identification information.  
      The server information obtaining unit  50  obtains server information (data retaining apparatus information) relating to another equipment (here, the server  20 ) connected to the network  10 . The server information obtaining unit  50  detects another equipment connected to the network  10  to obtain a UUDI (Universally Unique Identification), an IP (Internet Protocol) address, an MAC (Media Access Control) address, a server name, etc., of the detected another equipment as server information.  
      The server list updating unit  51  makes a server list on the basis of the server information about the another equipment on the network obtained by the server information obtaining unit  50 . Additionally, when the server information obtaining unit  50  obtains a change in the equipment (server) connected to the network  10 , the server list updating unit  51  updates the server list on the basis of the change.  
      The server list keeping unit  52  keeps the server list made and updated by the server list updating unit  51  on the basis of the server information obtained by the server information obtaining unit  50 .  
       FIG. 2  is a diagram showing a server list kept by the server list keeping unit  52 . As shown in  FIG. 2 , the server list includes a UUID, an IP address, an MAC address and a server name (data retaining apparatus name) of, and accessibility/inaccessibility information on each of other equipments (here, the server  20 ) connected to the network  10 .  
      Here, the UUID is a unique ID (for example, ID of 128 Bits) as a server name possessed by the server  20 , which is used to specify the server  20 . The IP address is an address used when the information processing apparatus  30  communicates with the server  20 . The MAC address is an address used when the activating unit  72  to be described later restores the server  20  to the activated state. The server name is used to be displayed on the displaying unit  60  connected to the information processing apparatus  30 . The accessibility/inaccessibility information (here, flag) is information representing whether the server  20  is accessible or not, updated on the basis of monitoring by the server monitoring unit  53  to be described later. Here, when the server  20  is accessible, the information is set to “1,” while set to “0” when the server  20  is inaccessible. Incidentally, in  FIG. 2 , the accessibility/inaccessibility information is set to “0.” 
      The server monitoring unit  53  comprises an activation state receiving unit  54  and an activation state confirming unit  55  to monitor whether the server  20  is accessible or not on the basis of the server information (here, the UUID, in particular) obtained by the server information obtaining unit  50 . The server monitoring unit  53  updates the accessibility/inaccessibility information in the server list kept by the server list keeping unit  52  on the basis of a situation of the monitoring (that is, whether the server  20  is accessible or not).  
      The activation state receiving unit  54  receives the activation/stop information transmitted from the activation state notifying unit  23  of the server  20 .  
      The activation state confirming unit  55  inquires the activation state from the server  20  to confirm the activation state of the server  20  when itself (that is, the information processing unit  30 ) is activated or when an application used to execute a process on contents data kept by the server  20  is activated.  
      Now, description will be made of a method of monitoring the server  20  by the server monitoring unit  53 . First, described is a method of monitoring (confirming the activation state of) the server  20  performed by the server monitoring unit  53  when the information processing apparatus  30  is activated.  FIG. 3  is a flowchart (steps S 100  to S 106 ) at the time that the server  20  is active. As shown in  FIG. 3 , when the information processing apparatus  30  is activated (step S 100 ), the activation state confirming unit  55  of the server monitoring unit  53  inquires the activation state from the server  20  (searches for the server) in order to confirm the activation state of the server  20  (step S 101 ). At this time, the activation state confirming unit  55  designates a destination address and a destination port on the basis of the server list shown in  FIG. 2  described above, and makes an inquiry. Since this information processing system  100  complies with UPnP (Universal Plug and Play), the inquiry is made by using SSDP (Simple Service Discovery Protocol).  
      When the server  20  receives the inquiry made by the activation state confirming unit  55  (step S 102 ), the activation state notifying unit  23  of the server  20  transmits a response (activation information) when the server  20  is active (step S 103 ) and the activation state receiving unit  54  receives the response from the server  20  (step S 104 ). At this time, the server  20  transmits the IP address and the like along with the UUID as transmission information of the response.  
      Next, the information processing apparatus  30  compares the UUID received by the activation state receiving unit  54  with a UUID in the server list kept by the server list keeping unit  52  (step S 105 ). When these UUDIs are in agreement with each other, the server monitoring unit  53  determines that the server  20  is active and is in the accessible state, and sets the accessibility/inaccessibility information on the server  20  in the server list to “accessible” (here, “1”). At this time, the IP address of the server  20  kept in the server list is updated.  
      As a result of comparison of the UUID received by the activation state receiving unit  54  with each of UUIDs in the server list kept by the server list keeping unit  52 , there is not found any UUID coinciding thereto in the server list (that is, when the server cannot be specified), the server monitoring unit  53  determines it as a new server connection, and obtains server information on a newly-connected server by means of the server information obtaining unit  50 , then newly registers this newly-connected server in the server list.  
       FIG. 4  is a flowchart in the case where the server  20  is inactive (steps S 110  to S 113 ). As shown in  FIG. 4 , when the information processing apparatus  30  is activated (step S 110 ), the activation state confirming unit  55  inquires of the server  20  in a manner similar to the above step S 101  (step S 111 ). Since a response is not transmitted from the server  20  when the server  20  is stopped or is in the inaccessible state, the activation state receiving unit  54  receives no response (step S 112 ). In this case, the server monitoring unit  53  determines that the server  20  is in the inaccessible state, and sets the accessibility/inaccessibility information on the server  20  in the server list kept by the server list keeping unit  52  to “inaccessible” (step S 113 ; here, the accessibility/inaccessibility information remaining “0 ” and being kept).  
      As this, the server monitoring unit  53  confirms the connection state to the network  10  of the server  20  (that is, whether accessible or not) when itself is activated.  
      On the other hand, description will be made of a method of monitoring (confirming the activation state of) the server  20  performed by the server monitoring unit  53  while the information processing apparatus  30  is active.  FIG. 5  is a flowchart (steps S 120  to S 124 ) in the case where the server  20  is stopped. When the server  20  is stopped and becomes inaccessible while the information processing apparatus  30  and the server  20  are both active, the server  20  notifies, by means of the activation state notifying unit  23 , the information processing apparatus  30  of stop information (activation/stop information) representing that itself is stopped by using SSDP (step S 120 ), and is stopped (step S 121 ). The activation state notifying unit  23  transmits the UUID to the information processing apparatus  30  together with a notification of the stop information by SSDP.  
      When the activation state receiving unit  54  of the information processing apparatus  30  receives the stop information and the UUID transmitted from the activation state notifying unit  23  of the server  20  (step S 122 ), the server monitoring unit  53  specifies the server  20  on the basis of the received UUID (step S 123 ), and sets the accessibility/inaccessibility information on the server  20  in the server list kept by the server list keeping unit  52  to “inaccessible” (step S 124 ; here, setting the accessibility/inaccessibility information to “0”).  
      Next, description will be made of a case where the server  20 , which has been stopped and inaccessible up to that time, is activated and becomes accessible while the information processing apparatus  30  is active.  FIG. 6  is a flowchart (steps S 130  to S 134 ) in the case where the server  20  is activated while the information processing apparatus  30  is active. As shown in  FIG. 6 , when the server  20  is activated (step S 130 ), the activation state notifying unit  23  of the server  20  notifies the information processing apparatus  30  of activation information (activation/stop information) representing that the server  20  is activated by using SSDP (step S 131 ). At this time, the activation state notifying unit  23  transmits the UUID to the information processing apparatus  30  together with the activation information.  
      When the activation state receiving unit  54  of the information processing apparatus  30  receives the activation information and the UUID transmitted from the activation state notifying unit  23  of the server  20  (step S 132 ), the server monitoring unit  53  specifies the server  20  on the basis of the received UUID (step S 133 ), and sets the accessibility/inaccessibility information on the server  20  in the server list kept by the server list keeping unit  52  to “accessible” (step S 134 ; here, setting the accessibility/inaccessibility information to “1”).  
      Incidentally, when the server cannot be specified at the above step S 133 , the server monitoring unit  53  determines it as a new server connection, obtains server information on the newly connected server by means of the server information obtaining unit  50 , and newly registers this newly connected server in the server list.  
      As this, the server monitoring unit  53  of the information processing apparatus  30  detects a change in the connection state of the server  20  to the network  10  (that is, whether accessible or not) on the basis of the activation/stop information notified from the activation state notifying unit  23  of the server  20 .  
      The displaying unit  60  is, for example, a monitor. The display controlling unit  61  controls display contents on the displaying unit  60 .  
      The display controlling unit  61  performs a display control on the basis of an application program executing a process on contents data to display a contents name registered in the contents list, a server name in which contents data of the contents name is kept, and information representing whether the contents data of the contents name is accessible or not on the displaying unit  60 , on the basis of the contents list kept by the contents list keeping unit  42  and the server list kept by the server list keeping unit  52 .  
      Namely, the display controlling unit  61  confirms a server name in which contents data of the contents name is kept on the basis of the contents list when displaying the contents name registered in the contents list on the displaying unit  60 , and confirms whether the contents data of the contents name to be displayed on the displaying unit  60  is accessible or not by confirming the accessibility/inaccessibility information on a server of the server name on the basis of the server list. The display controlling unit  61  changes the display on the displaying unit  60  according to whether the contents data is accessible or not.  
      When the contents data is accessible, the display controlling unit  61  displays only a contents name of the contents data on the displaying unit  60 , for example. When the contents data is inaccessible, the display controlling unit  61  displays an X-mark together with the contents name of the contents data on the displaying unit  60  (refer to  FIG. 8  to be described later).  
      At this time, the display controlling unit  61  performs the display control on the basis of the contents list (namely, the latest contents list) based on contents information that the contents information obtaining unit  40  obtains latest.  
      In other words, the contents list used for display on the displaying unit  60  by the display controlling unit  61  is a contents list as the latest history based on contents information that the contents information obtaining unit  40  obtains latest in order to display it on the displaying unit  60 .  
      Accordingly, in the case where an access to the server  20  is possible when the display controlling unit  61  newly displays a contents name or the like on the displaying unit  60 , display based on contents information newly obtained by the contents information obtaining unit  40  is performed. In the case where an access to the server is impossible because the activation state of the server  20  is the stand-by state or the pause state, display is performed on the basis of the latest contents list kept beforehand by the contents list keeping unit  42 , and the X-mark is displayed together with the contents name.  
      Now, an example of display on the displaying unit  60  will be explained.  FIG. 7  is an example of display on the displaying unit  60  in the case where an access to the server  20  is possible.  FIG. 8  is an example of display on the displaying unit  60  in the case where an access to the server  20  is impossible. As shown in  FIG. 7 , when an access to the server  20  is possible, contents names (music A to C) of contents data (here, music data) kept by the server  20  are displayed on the displaying unit  60  on the basis of the latest contents list. As shown in  FIG. 8 , when an access to the server  20  is impossible, the X-mark is displayed on the left of the contents name (music A to C) as information (here, information representing “inaccessible”) representing whether an access to the contents data is accessible or not.  
      A shaded contents name (here, music B) in  FIGS. 7 and 8  is designated by an input device such as a mouse or the like connected to the information processing apparatus  30 , for example, representing a contents name selected by the contents selecting unit  70  to be described later. In the examples of display shown in  FIGS. 7 and 8 , a server name (here, server A) of the server  20  that keeps contents data of the contents name selected by the contents selecting unit  70  is displayed in a column denoted by a reference numeral  62  on the top right-hand corner on the screen. An Operation button group  63  shown in  FIGS. 7 and 8  is used to execute a process on contents data of a selected contents name.  
      The contents selecting unit  70  selects a contents data, on which a process is to be executed, on the basis of the contents list. Here, a user who is operating the information processing apparatus  30  selects a contents name that the user desires to execute a process thereon among contents names displayed on the displaying unit  60 , thereby selecting contents data of this contents name.  
      The contents processing unit  71  executes a process (when the contents data is music data, regeneration, edition or the like of the music, for example) on the contents data selected by the contents selecting unit  70 .  
      The activating unit  72  activates (restores the power source state to the ON state) the server  20  in order to enable an access to the server  20  when the server  20  that keeps the contents selected by the contents selecting unit  70  is in the inaccessible state (that is, when the accessibility/inaccessibility information about the server  20  indicates “inaccessible”).  
      Now, description will be made of a procedure for restoring the server  20  to the active state by the activating unit  72  with reference to a flowchart (steps S 140  to S 147 ) shown in  FIG. 9 .  
      As shown in  FIG. 9 , the information processing apparatus  30  first selects a server (here, the server  20 ) to be restored to the activation state (turning the power source state thereof to the ON state) (step S 140 ). The information processing apparatus  30  specifies an MAC address from the UUID of the selected server  20  on the basis of the server list kept by the server list keeping unit  52  (step S 141 ), and transmits an activate instruction (MP: Magic Packet) to turn the power source state of the server  20  to the active state from the activating unit  72  to the power source controlling unit  22  of this server  20 , designating this MAC address (step S 142 ).  
      When receiving the activate instruction (MP) from the activating unit  72  of the information processing unit  30  (step S 143 ), the power source controlling unit  22  of the server  20  determines whether the power source controlling unit  22  itself complies with the activate instruction transmitted from the activating unit  72  (step S 144 ).  
      When not complying with the activate instruction (MP) (No route at step S 144 ), the server  20  terminates the process (step S 145 ).  
      When complying with the activate instruction (MP) (Yes route at step S 144 ), the server  20  confirms whether the MAC address designated by the activating unit  72  agrees with its own MAC address (step S 146 ).  
      When the MAC address designated by the activating unit  72  does not agree with its own MAC address (No route at step S 146 ), the server  20  terminates the process (step S 145 ). When the MAC address designated by the activating unit  72  agrees with own MAC address (Yes route at step S 146 ), the power source controlling unit  22  of the server  20  restores its own power source to the active state (ON state) (step S 147 ).  
      Next, description will be made of a contents displaying method (data displaying method; operation of the information processing system  100 ) according to the embodiment of this invention. In the contents displaying method according to the embodiment of this invention, the initial setting shown in a flowchart (steps S 1  to S 6 ) in  FIG. 10  is performed at the time of the initial operation (activation) of the information processing system  100 .  
      Namely, when the information processing apparatus  30  is initially activated, the server information obtaining unit  50  obtains server information about another equipment (here, the server  20 ) connected to the network  10  (step S 1 ; data retaining apparatus information obtaining step), the server list updating unit  51  makes the server list shown in  FIG. 2  described above (step S 2 ; data retaining apparatus list making step), and the server list keeping unit  52  keeps the made server list (step S 3 ; data retaining apparatus list keeping step).  
      The contents information obtaining unit  40  obtains contents information on contents data kept by the server  20  from the server  20  connected to the network  10  on the basis of the server list kept by the server list keeping unit  52 , by using a retrieving function of UPnP, for example (step S 4 ; data information obtaining step).  
      The contents list updating unit  41  then makes a contents list on the basis of the contents information obtained at the contents information obtaining step S 4 , by using at least a contents name and a retaining place of contents data of this contents name (step S 5 ; data list making step), and the contents list keeping unit  42  keeps the made contents list (step S 6 ; data list keeping step).  
      The information processing apparatus  30  executes a process on contents data by using the server list and the contents list made and kept as this.  
       FIG. 11  is a flowchart (steps S 10  to S 21 ) showing a procedure for a contents displaying method (operation of the information processing system  100 ) according to the embodiment of this invention.  
      As shown in  FIG. 11 , in the information processing system  100 , the server monitoring unit  53  always monitors the connection state (that is, the activation state) of the server  20  as described above with reference to  FIGS. 3 through 6  (step S 10 ; data retaining apparatus monitoring step), and updates the accessibility/inaccessibility information kept in the server list according to a situation of the monitoring (step S 11 ).  
      When a display instruction to display contents on the display  60  is generated by the user who is operating the information processing apparatus  30  (step S 12 ), the contents information obtaining unit  40  retrieves contents data kept in the contents data keeping unit  21  of the server  20  and again obtains contents information (step S 14 ) when the server  20  is accessible (Yes route at step S 13 ).  
      Next, the contents list updating unit  41  updates the contents list kept by the contents list keeping unit  42  on the basis of the contents information obtained this time (step S 15 ), and the contents list keeping unit  42  keeps the updated contents list (step S 16 ; data list keeping step).  
      When the server  20  is inaccessible (No route at step S 13 ), the processes at the above steps S 14  to S 16  are not carried out.  
      The display controlling unit  61  performs the display control in order to display the contents name on the displaying unit  60  on the basis of the contents list kept by the contents list keeping unit  42  and the server list kept by the server list keeping unit  52  (step S 17 ; display controlling step). Namely, the display controlling unit  61  performs the display control on the basis of the contents list newly updated this time when the server  20  is accessible. When the server  20  is inaccessible, the display controlling unit  61  performs the display control on the basis of the contents list kept latest by the contents list keeping unit  42 . At this time, the accessibility/inaccessibility information in the server list indicates “inaccessible” because the server  20  is inaccessible. Thus, the display controlling unit  61  displays the X-mark together with the contents name on the displaying unit  60 .  
      When the process on the contents data displayed on the displaying unit  60  is performed, the user of the information processing apparatus  30  selects a contents name displayed on the displaying unit  60  in order to execute a process on the contents data. Namely, the user selects contents that the user desires to execute a process thereon on the basis of the latest contents list kept by the contents list keeping unit  42  (step S 18 ; data selecting step).  
      When the server  20  keeping the selected contents is in the inaccessible state (Yes route at step S 19 ), the activating unit  72  activates the server  20  to bring the server into the accessible state in order to make the contents data selected at the above step S 18  usable (step S 20 ; activating step).  
      When the server  20  is accessible (No route at step S 19 ), the process at the above step S 20  is not performed.  
      The contents processing unit  71  executes a process (regeneration, edition or the like of music when the content data is music data, for example) on the contents data selected at the above step S 18  (step S 21 ).  
      As above, according to the information processing system  100  and the contents displaying method as being the embodiment of this invention, it is possible to display a display (contents name) of contents data kept by the server  20  on the displaying unit  60  on the basis of a contents list kept latest by the contents list keeping unit  42  even if an access to the server  20  is impossible because the contents list keeping unit  42  keeps contents information obtained by the contents information obtaining unit  40  as a contents list.  
      The user cannot discriminate whether displayed contents are accessible (usable) or not only by displaying them on the displaying unit  60  on the basis of the latest contents list. According to the information system  100  and the contents displaying method as being the embodiment of this invention, the server monitoring unit  53  always monitors the connection state of the server  20  and sets the accessibility/inaccessibility information in the server list kept by the server list keeping unit  52  to “inaccessible” when the server  20  is inaccessible, and the display controlling unit  61  displays information representing whether the server  20  keeping contents data of a contents name displayed on the displaying unit  60  is accessible or not (that is, whether the contents data is accessible or not) on the basis of this accessibility/inaccessibility information. Whereby, the user using the information processing apparatus  30  can discriminate at a glance whether contents being now displayed on the displaying unit  60  are usable or not.  
      Since the display controlling unit  61  displays, on the displaying unit  60 , a server name of the server  20  keeping contents data of this contents name together with the contents name on the basis of the contents list kept by the contents list keeping unit  42 , the user using the information processing apparatus  30  can recognize at a glance which server is inaccessible.  
      Since the activating unit  72  can activate the server  20  in order to make the server  20  accessible when the server  20  is in the stand-by state or in the pause state, or when the power source condition thereof is the OFF state, the user using the information processing apparatus  30  can readily activate (restore the power source condition to the ON state) the server  20  without bothering to go up to a place where the server  20  is installed.  
      [2] As to Modifications of the Invention  
      Note that the present invention is not limited to the above embodiment, but may be modified in various ways without departing from the scope of the invention.  
      The above embodiment has been described by way of example where only the server  20  is connected as an equipment connected to the network  10  other than the information processing apparatus  30 . However, this invention is not limited to this. Like an information processing system  101  shown in  FIG. 12 , a plurality (here, two) servers  20  and  200  may be connected to the network  10 , for example. Incidentally, the server  200  is configured similarly to the server  20 . In this case, the information processing apparatus  30  performs a process on the server  200  similar to the process on the server  20 .  
      Accordingly, when the server  20  is in the accessible state but the server  200  is in the inaccessible state, for example, the contents information obtaining unit  40  newly obtains contents information about the accessible server  20 , and the display controlling unit  61  displays on the basis of a contents list based on the newly obtained contents information. On the other hand, for the inaccessible server  200 , the display controlling unit  61  displays on the basis of a contents list based on contents information obtained latest by the contents information obtaining unit  40 .  
      In this case, the display controlling unit  61  attaches, on the displaying unit  60 , the X-mark to contents names (music D to F) of contents data kept by the server  200 , while not attaching the X-mark to contents names (music A to C) of contents data kept by the server  20 , as shown in  FIG. 13 .  
      In the above embodiment, the information processing apparatus  30  performs the process on only contents data kept by the server  20 . However, this invention is not limited to this. For example, like the information processing system  102  shown in  FIG. 14 , the information processing apparatus  30  may have a contents data keeping unit  80  for keeping contents data, and the contents processing unit  71  of the information processing apparatus  30  may perform a process on the contents data kept by the contents data keeping unit  80 . In which case, the contents information obtaining unit  40 , the contents list updating unit  41  and the contents list keeping unit  42  handle the contents data kept by the contents data keeping unit  80  in a manner similar to the manner of handling the contents data kept in the contents data keeping unit  21  of the server  20 .  
      Further, like an information processing system  103  shown in  FIG. 15 , a plurality (here, two) of information processing apparatuses  90  having both the function of the server  20  described above and the function of the information processing apparatus  30  described above may be connected on the network  10 , and these information processing apparatuses  90  may operate as both the above information processing apparatus  30  and the above server  20 , for example.  
      In the above embodiment, the accessibility/inaccessibility information about the server  20  is kept in only the server list. However, this invention is not limited to this. Alternatively, the accessibility/inaccessibility information about the server  20  may be kept in the contents list.  
      The above embodiment has been described by way of only one example where the display controlling unit  61  displays contents names on the displaying unit  60  as shown in  FIGS. 7 and 8 , for example. However, in the above-described embodiment, the display controlling unit  61  may display a server name (here, server A) of the server  20  connected to the network  10  on the basis of the server list kept by the server list keeping unit  52  as shown in  FIG. 16 , for example. In which case, the X-mark as being information representing that the server  20  is inaccessible is displayed together with a server name of the server  20  when the server  20  is inaccessible, on the basis of the accessibility/inaccessibility information kept in the server list, as shown in  FIG. 16 .  
      In the above embodiment, the activating unit  72  may be activated by operating a mouse connected to the information processing apparatus  30  in a predetermined way. On a display screen shown in  FIG. 8  or a display screen shown in  FIG. 16 , the user selects a contents name or a server name attached the X-mark that the user desires to perform a process by operating the mouse, and operates the mouse in a predetermined way (for example, right-click, left-click, double-click) to operate the activating unit  72 , for example. Whereby, the user using the information processing apparatus  30  can readily activate the server without any cumbersome operation.  
      At this time, a display shown in  FIG. 17  may be displayed once on the displaying unit  60 , and a restore button  64  on the display screen may be again clicked by the mouse to operate the activating unit  72 .  
      [3] Others  
      The functions of the power source controlling unit  22 , the activation state notifying unit  23 , the contents information obtaining unit (data information obtaining unit)  40 , the contents list updating unit (data list updating unit)  41 , the contents list keeping unit (data list keeping unit)  42 , the server information obtaining unit (data retaining apparatus information obtaining unit)  50 , the server list updating unit (data retaining apparatus list updating unit)  51 , the server list keeping unit (data retaining apparatus list keeping unit)  52 , the server monitoring unit (data retaining apparatus monitoring unit)  53 , the activation state receiving unit  54 , the activation state confirming unit  55 , the display controlling unit  61 , the contents selecting unit (data selecting unit)  70 , the contents processing unit (data processing unit)  71  and the activating unit  72  are realized by executing a predetermined program (data displaying program) by a computer (including CPU, information processing apparatus, various terminals).  
      This program is provided in a form in which the program is recorded on a computer readable recording medium such as a flexible disk, a CD-ROM, a CD-R, a CD-RW, a DVD or the like. In this case, the computer reads the data displaying program from the recording medium, transfers the program to the internal storage or an external storage to store it, and uses the same. The program may be recorded on a storage (recording medium) such as a magnetic disk, an optical disk, a magneto-optical disk or the like, and provided to the computer from the storage over a communication line.  
      Here, the computer is a concept including hardware and an OS (Operating System), standing for hardware operating under control of the OS. When the OS is unnecessary and the application program solely operates the hardware, the hardware itself corresponds to the computer. The hardware has at least a microprocessor such as a CPU or the like, and a means for reading the computer program recorded on the recording medium. The application program as being the above data displaying program includes program codes for making the computer realize the functions of the power source controlling unit  22 , the activation state notifying unit  23 , the contents information obtaining unit  40 , the contents list updating unit  41 , the contents list keeping unit  42 , the server information obtaining unit  50 , the server list updating unit  51 , the server list keeping unit  52 , the server monitoring unit  53 , the activation state receiving unit  54 , the activation state confirming unit  55 , the display controlling unit  61 , the contents selecting unit  70 , the contents processing unit  71  and the activating unit  72 . A part of these functions may be realized by, not the application program, but the OS.  
      As the recording medium in the embodiment of this invention, there may be used various kinds of computer readable media such as an IC card, a ROM cartridge, a magnetic tape, a punched card, an internal storage (memory such as RAM, ROM or the like) of a computer, an external storage, a printed matter on which codes such as bar codes or the like are printed and so forth, other than a flexible disk, a CD-ROM, a CD-R, a CD-RW, a DVD, a magnetic disk, an optical disk and a magneto-optical disk mentioned above.