Patent Publication Number: US-2017374410-A1

Title: Information processing apparatus, information processing method, and program

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. application Ser. No. 15/249,040, filed Aug. 26, 2016, which is a continuation of U.S. application Ser. No. 14/538,083, filed Nov. 11, 2014, which is a continuation of U.S. application Ser. No. 13/934,473, filed Jul. 3, 2013, now U.S. Pat. No. 8,914,832, which claims the benefit of priority of Provisional Application Ser. No. 61/737,469, filed Dec. 14, 2012, the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     The present disclosure relates to an information processing apparatus, an information processing method, and a program, and particularly to an information processing apparatus, an information processing method, and a program suitable for use in a case where content displayed on a certain screen device which configures a home network is identified by an ACR (Automatic Content Recognition) service and metadata corresponding to the content is displayed, on a different screen device or an application is executed in accordance with the progression of the content. 
     For example, it is supposed to display, to a viewer of a TV (television) program, information (performers, a plot outline, a trailer and so forth) relating to the TV program (hereinafter referred to simply as program) being broadcast, information useful to a viewer (news, weather forecast, traffic information and so forth) although it does not have a direct relationship to the program, and so forth on the screen. 
     In order to implement this, a command used to acquire and start up an application program for exclusive use (hereinafter referred to simply as application) may be transmitted to a TV receiver or the like in a linked relationship with the progression of the program. Actually, in Japan, Europe and so forth, this has been implemented by transmitting the command or the application making use of a frequency band for data broadcasting in a TV broadcasting signal (refer to, for example, Japanese Patent Laid-Open No. 2006-50237). 
     In the meantime, in the United States, a frequency band for data broadcasting is not provided in a TV broadcasting signal, and a replacing method is not established. Therefore, it has not been implemented to execute an application in a linked relationship with the progression of a program. 
     It is to be noted that, in the United States, the number of households in which a program is viewed through a CATV, an IPTV or the like is greater than the number of households in which a TV broadcasting wave is received directly by and viewed on a TV receiver. Since the CATV or the IPTV sometimes extracts only video and audio signals of a program from a TV broadcasting signal and distributes the video and audio signals, even if a frequency band for data broadcasting is provided in a TV broadcasting signal in the United states, there is no guarantee that a data broadcasting signal including an application and related data is transmitted to a reception apparatus. 
     Further, it is requested recently to execute, even in a case in which not only a program being broadcast but also a program recorded, videos reproduced from a package medium such as a DVD or a BD, moving pictures, music or the like downloaded through the Internet (such programs and so forth mentioned are hereinafter referred to as content) are being viewed, an application in a linked relationship with the progression of the content. 
     In order to implement this request, it is necessary to identify the piece of content being viewed, and as one method therefor, a technique called ACR (Automatic Content Recognition) service is available (refer, for example, to Japanese Patent Laid-Open No. 2012-168801). 
     The ACR service is implemented by an ACR client and an ACR server. The ACR client, which is incorporated in a content reproduction apparatus such as a TV receiver, extracts, from content being viewed, signature data representative of a characteristic of the content and notifies the ACR server to request identification of the content. The ACR server compares the received signature data with signature data of content recorded in a database in advance to identify the content being viewed on the content reproduction apparatus. Further, the ACR server issues an ACR response including metadata relating to the identified content and information indicative of an application to be executed in a linked relationship (such application is hereinafter referred to as linked application) to the ACR client. 
     The content reproduction apparatus in which the ACR client which receives the response is incorporated acquires a linked application from a predetermined server and executes the linked application. 
     SUMMARY 
     Incidentally, in the United States, as a result of popularization of a CATV, an IPTV and so forth, a TV receiver is positioned as a displaying outputting device of an external apparatus such as a set top box of a CATV, an IPTV or the like as described above. 
     Therefore, a user has few opportunities to operate a remote controller of a TV receiver but frequently operates a remote controller of the external apparatus. Therefore, there is the possibility that an operation for a linked application started up in a TV receiver as a content reproduction apparatus which is operated by a remote controller of the TV receiver may not be favorable in convenience in use to the user. 
     Accordingly, taking the convenience to a user into consideration, a request to cause a second screen device, which is different from a content reproduction apparatus (TV receiver or the like) in which an ACR client is incorporated, to display metadata relating to content-being viewed on the content reproduction apparatus or to execute a linked application has been and is being generated. 
     Here, as the second screen device, for example, a tablet type terminal, a slate PC, a smartphone and so forth can be listed. 
     Further, in recent years, a second screen device of the type which can operate the external apparatus with a predetermined application program started up in the second screen device, namely, of the type which can be utilized as a remote controller for the external apparatus, is available. Therefore, implementation of the request described above is desired also from a point of view that operation inputting devices for a content reproduction apparatus and an external apparatus are consolidated on the second screen device. 
     Furthermore, mainly in the United States, there is a tendency that the screen size of a TV receiver and so forth as a content reproduction apparatus becomes greater than 50 to 60 inches, and a utilization form in which a plurality of pieces of content different from each other are displayed and viewed simultaneously on the screen of the increased size begins to be gradually popularized. Accordingly, also it is necessary to consider also a utilization form in which an ACR client is built in a TV receiver or the like which has such a large-sized screen and is linked with a second screen device. In the following description, a TV receiver or the like which has a large-sized screen and can display a plurality of different pieces of content at the same time is referred to as a multi-window screen device. 
       FIG. 1  is a schematic view of a space in a case where it is assumed to link a multi-window screen device in which an ACR client is built and a second (2nd) screen device with each other to utilize an ACR service and the devices are disposed in a home of a user or the like. 
     In  FIG. 1 , a multi-window screen device  1 - 1  is installed on the front of the user, and a multi-window screen device  1 - 2  is installed on a left side wall. A second screen device  3  is disposed in the proximity of the user. 
     A plurality of (in the case of  FIG. 1 , three) windows can be provided on the multi-window screen device  1 - 1 , and different pieces of content (which may be the same as each other) can be displayed at the same time in the windows. In the following description, for example, the piece of content displayed in a window A is referred to as content A. This similarly applies also to the other pieces of content displayed in the other windows. 
     The multi-window screen device  1 - 1  can transfer an ACR response, which includes an identification result and so forth of the pieces of content displayed in the windows, to the second screen device  3  by utilizing an ACR service. 
     Also the multi-window screen device  1 - 2  is similar to the multi-window screen device  1 - 1 . However, in  FIG. 1 , the multi-window screen device  1 - 2  is in a state in which only a window X is provided on the screen thereof and a content X is displayed in the window X. 
     The second screen device  3  can simultaneously display metadata corresponding to the pieces of content displayed in the windows of the multi-window screen device  1 - 1  or the multi-window screen device  1 - 2  and a started-up linked application in accordance with the progression of the content. 
     In the case of  FIG. 1 , the second screen device  3  is in a state in which a linked application A to the content A of the window A, another linked application C to the content C of the window C and metadata X of the content X of the window X are displayed simultaneously. 
     In the case where the utilization form illustrated in  FIG. 1  is assumed, there is the possibility that the user may not be able to rapidly grasp a corresponding relationship of the pieces of information (videos of the linked applications and metadata) displayed on the screen of the second screen device  3  to the pieces of content displayed in the windows of the multi-window screen devices  1 - 1  and  1 - 2 . 
     Accordingly, a contrivance allowing a user to rapidly grasp a corresponding relationship between a plurality of pieces of content which can be displayed simultaneously in the windows of the multi-window screen devices  1 - 1  and  1 - 2  and a plurality of pieces of information (videos of linked applications and metadata) which can be displayed on the second screen device  3  is required. 
     The present disclosure has been made in view of such a situation as described above and makes it possible for a user to rapidly grasp a corresponding relationship between a plurality of pieces of content which can be displayed simultaneously and information which is displayed separately. 
     According to a first mode of the present disclosure, there is provided an information processing apparatus which cooperates with a terminal apparatus to configure a home network system, including: a frame visual attribute setting section configured to set a frame visual attribute to a window provided on a screen to display a reproduced piece of content; a publication section configured to publish a command adapted to request notification of the frame visual attribute set to the window from the terminal apparatus to the terminal apparatus; and a notification section configured to notify the terminal apparatus of the frame visual attribute of the window in response to calling of the command from the terminal apparatus. 
     The display control section may set, to a plurality of windows provided on the screen to display a plurality of different pieces of content therein, different frame visual attributes, and the publication section may publish a command adapted to request notification of the frame visual attributes of the plurality of windows from the terminal apparatus to the terminal apparatus. 
     The frame visual attribute setting section may change the frame visual attributes of the windows in response to a request issued from the terminal apparatus utilizing the command. 
     The publication section may describe a URL of the command directly in the device description described expanding a prescription of UPnP to publish the URL of the command to the terminal apparatus. 
     The command may be WebAPI. 
     The publication section may multicast distribute a Notify message on the home network and publish the device description to the terminal apparatus in response to an access from the terminal apparatus based on the Notify message. 
     The publication section may publish the device description to the terminal apparatus in response to M-Search from the terminal apparatus. 
     According to the first mode of the present disclosure, the information processing apparatus may further include an identification request processing section configured to extract, from a reproduced piece of content, signature data representative of a characteristic of the piece of content, generate and transmit a query including at least the extracted signature data to an identification server and receive a response transmitted thereto from the identification server in response to the query and representative of a result of the identification of the reproduced piece of content, and the publication section may publish also a command adapted to render the identification request processing section operative from the terminal apparatus to the terminal apparatus. 
     According to the first mode of the present disclosure, there is provided an information processing method for an information processing apparatus which cooperates with a terminal apparatus to configure a home network system,, the method executed by the information processing apparatus, including: a frame visual attribute setting step of setting a frame visual attribute to a window provided on a screen to display a reproduced piece of content; a publication step of publishing a command adapted to request notification of the frame visual attribute set to the window from the terminal apparatus to the terminal apparatus; and a notification step of notifying the terminal apparatus of the frame visual attribute of the window in response to calling of the command from the terminal apparatus. 
     According to the first mode of the present disclosure, there is provided a program used to cause a computer, which cooperates with a terminal apparatus to configure a home network system, to function as: a frame visual attribute setting section configured to set a frame visual attribute to a window provided on a screen to display a reproduced piece of content; a publication section configured to publish a command adapted to request notification of the frame visual attribute set to the window from the terminal apparatus to the terminal apparatus; and a notification section configured to notify the terminal apparatus of the frame visual attribute of the window in response to calling of the command from the terminal apparatus. 
     In the first mode of the present disclosure, a frame visual attribute is set to a window provided on a screen to display a reproduced piece of content, and a command adapted to request notification of the frame visual attribute set to the window from the terminal apparatus is published to the terminal apparatus. Further, the terminal apparatus is notified of the frame visual attribute of the window in response to calling of the command from the terminal apparatus. 
     According to a second mode of the present disclosure, there is provided an information processing apparatus which cooperates with a content displaying apparatus, displaying a piece of content in a window provided on a screen, to configure a home network system, including: a command acquisition section configured to acquire a command adapted to request notification of a frame visual attribute set to the window provided on the screen of the content displaying apparatus to display a reproduced piece of content from the content displaying apparatus and call the command to receive notification of the frame visual attribute; a linked application execution section configured to acquire and execute a linked application to be executed in accordance with the progression of the piece of content displayed in the window provided on the screen of the content displaying apparatus; and a frame displaying controlling section configured to set a frame visual attribute same as the notified frame visual attribute to a frame in which an image by the linked application is to be displayed. 
     The command acquisition section may acquire a URL of the command described directly in a device description published by the content displaying apparatus and described expanding a prescription of UPnP. 
     The command may be WebAPI. 
     The command acquisition section may acquire the device description from the content displaying apparatus based on a Notify message multicast distributed on the home network by the content displaying apparatus. 
     The command acquisition section may acquire the device description supplied thereto from the content displaying apparatus searched out by M-Search. 
     The content displaying apparatus may include an identification request processing section configured to extract, from a reproduced piece of content, signature data representative of a characteristic of the piece of content, generate and transmit a query including at least the extracted signature data to an identification server and receive a response transmitted back from the identification server in response to the query and representative of a result of the identification of the reproduced piece of content. The command acquisition section may acquire also a command adapted to render the identification request processing section of the content displaying apparatus operative from the content displaying apparatus and receives the response transferred thereto from the content displaying apparatus by calling the command, and the linked application execution section may acquire and execute the linked application based on related metadata included in the received response and corresponding to the identified piece of content. 
     According to the second mode of the present disclosure, there is provided an information processing method for an information processing apparatus which cooperates with a content displaying apparatus, displaying a piece of content in a window provided on a screen, to configure a home network system, the method executed by the information processing apparatus, including: an acquisition step of acquiring a command adapted to request notification of a frame visual attribute set to the window provided on the screen of the content displaying apparatus to display a reproduced piece of content from the content displaying apparatus; a reception step of calling the command to receive the notification of the frame visual attribute; a linked application execution step of acquiring and executing a linked application to be executed in accordance with the progression of the piece of content displayed in the window provided on the screen of the content displaying apparatus; and a frame displaying controlling step of setting a frame visual attribute same as the notified frame visual attribute to a frame in which an image by the linked application is to be displayed. 
     According to the second mode of the present disclosure, there is provided a program used to cause a computer, which cooperates with a content displaying apparatus, displaying a piece of content in a window provided on a screen, to configure a home network system, to function as: a command acquisition section configured to acquire a command adapted to request notification of a frame visual attribute set to the window provided on the screen of the content displaying apparatus to display a reproduced piece of content from the content displaying apparatus and call the command to receive notification of the frame visual attribute; a linked application execution section configured to acquire and execute a linked application to be executed in accordance with the progression of the piece of content displayed in the window provided on the screen of the content displaying apparatus; and a frame displaying controlling section configured to set a frame visual attribute same as the notified frame visual attribute to a frame in which an image by the linked application is to be displayed. 
     In the second mode of the present disclosure, a command adapted to request notification of a frame visual attribute set to the window provided on the screen of the content displaying apparatus to display a reproduced piece of content is acquired from the content displaying apparatus, and the command is called to receive notification of the frame visual attribute. A linked application to be executed in accordance with the progression of the piece of content displayed in the window provided on the screen of the content displaying apparatus is acquired and executed, and a frame visual attribute same as the notified frame visual attribute is set to a frame in which an image by the linked application is to be displayed. 
     According to a third mode of the present disclosure, there is provided an information processing method for a home network system which includes a content displaying apparatus and a terminal apparatus, including: a frame visual attribute setting step by the content displaying apparatus of setting a frame visual attribute to a window provided on a screen to display a reproduced piece of content; a publication step by the content displaying apparatus of publishing a command adapted to request notification of the frame visual attribute set to the window from the terminal apparatus to the terminal apparatus; an acquisition step by the terminal apparatus of acquiring the published command; a notification step by the content displaying apparatus of notifying the terminal apparatus of the frame visual attribute of the window in response to calling of the command by the terminal apparatus; a linked application execution step by the terminal apparatus of acquiring and executing a linked application to be executed in accordance with the progression of the piece of content displayed in the window provided on the screen of the content displaying apparatus; and a frame displaying controlling step by the terminal apparatus of setting a frame visual attribute same as the notified frame visual attribute to a frame in which an image by the linked application is to be displayed. 
     In the third mode of the present disclosure, by the content displaying apparatus, a frame visual attribute is set to a window provided on a screen to display a reproduced piece of content, and a command adapted to request notification of the frame visual attribute set to the window from the terminal apparatus is published to the terminal apparatus. Meanwhile, by the terminal apparatus, the published command is acquired. Further, by the content displaying apparatus, the terminal apparatus is notified of the frame visual attribute of the window in response to calling of the command by the terminal apparatus. Then, by the terminal apparatus, a linked application to be executed in accordance with the progression of the piece of content displayed in the window provided on the screen of the content displaying apparatus is acquired and executed. Thereupon, a frame visual attribute same as the notified frame visual attribute is set to a frame in which an image by the linked application is to be displayed. 
     With the first mode of the present disclosure, the terminal apparatus can be notified of a frame visual attribute set to a window displaying a piece of content. 
     With the second mode of the present disclosure, a frame visual attribute same as the frame visual attribute set to the window displaying a piece of content on the content displaying apparatus can be set to a frame adapted to display an image by a linked application to be executed in accordance with the progression of the piece of content. 
     With the third mode of the present disclosure, a common frame visual attribute can be set to both of a window displaying a piece of content on the content displaying apparatus and a frame adapted to display an image by a linked application to be executed in accordance with the progression of the piece of content by the terminal apparatus. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of a space in the case where a multi-window screen device and a second screen device are linked with each other and an ACR service is utilized; 
         FIG. 2  is a schematic view of a space illustrating an outline of the present disclosure; 
         FIG. 3  is a block diagram showing an example of a configuration of an ACR service utilization system which is an embodiment of the present disclosure; 
         FIG. 4  is a block diagram showing an example of a configuration of an ACR server; 
         FIG. 5  is a block diagram showing an example of a configuration of an ACR client; 
         FIG. 6  is a view illustrating a data structure of ACR reference data; 
         FIG. 7  is a view illustrating a data structure of an ACR query; 
         FIGS. 8A and 8B  are views each illustrating a data structure of an ACR response; 
         FIG. 9  is a flow chart illustrating a pre-process in a home network system; 
         FIG. 10  is a flow chart illustrating another pre-process in the home network system; 
         FIG. 11  is a flow chart illustrating operations of the ACR service utilization system; and 
         FIG. 12  is a block diagram showing an example of a configuration of a computer. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the following, a best mode for carrying out the present disclosure (hereinafter referred to as embodiment) is described in detail with reference to the drawings. 
     Outline of ACR Serve Utilization System 
       FIG. 2  shows an outline of an ACR service utilization system which is an embodiment of the present disclosure. The ACR service utilization system includes multi-window screen devices  40 - 1  and  40 - 2  and a second screen device  50  which have a built-in ACR client and causes the devices to link with each other to utilize an ACR service. 
     In  FIG. 2 , the multi-window screen device  40 - 1  is installed on the front of a user, and the multi screen device  40 - 2  is installed on a left side wall. In the proximity of the user, the second screen device  50  is disposed. 
     A plurality of (in the case of  FIG. 2 , three) windows can be provided on a screen of the multi-window screen device  40 - 1 , and pieces of content different from each other (which may be the same as each other) can be displayed in the windows simultaneously. In the following description, for example, the piece of content displayed in a window A is referred to as content A. This similarly applies also to the other pieces of content displayed in the other windows. 
     Further, the multi-window screen device  40 - 1  can transfer an ACR response, which includes an identification result and so forth of the pieces of content displayed in the windows, to the second screen device  50  by utilizing the ACR service. 
     Furthermore, the multi-window screen device  40 - 1  can provide, to a frame of each window, an attribute (hereinafter referred to as frame visual attribute) which can be visually distinguished from frames of the other windows (including the window of the multi-window screen device  40 - 2 ). 
     As the frame visual attribute, a color, a thickness and a type of a frame line, a depth of three-dimensional display and so forth which can be set and changed by the CSS (Cascading Style Sheets) can be listed. In the case of  FIG. 2 , the frame line of each window is set different from those of the frames of the other windows, and the frame line of the window A is set to an alternate long and short dash line; the frame line of the window B is set to a solid line; and the frame line of the window C is set to a broken line. 
     The multi-window screen device  40 - 2  is similar to the multi-window screen device  40 - 1 . However, in  FIG. 2 , the multi-window screen device  40 - 2  is in a state in which only a window X is provided on the screen thereof and the frame line of the window W is set to an alternate long and two short dashes line to display content X. 
     In the second screen device  50 , metadata corresponding to the pieces of content displayed in the windows of the multi-window screen devices  40 - 1  and  40 - 2  and a linked application conforming to the progression of the content can be started up and displayed. 
     Further, in the second screen device  50 , it is possible to provide a frame to each piece of information to be displayed (a screen image of metadata or a linked application corresponding to the content)and set, to the frame, a frame visual attribute similar to that of the frame of the window in which the corresponding content is displayed. 
     In particular, in the case of  FIG. 2 , the second screen device  50  is in a state in which the linked application A corresponding to the content A of the window A is displayed in the frame of an alternate long and short dash line; the linked application C corresponding to the content C of the window C is displayed in the frame of a broken line; and metadata X corresponding to the content X of the window X is displayed in the frame of an alternate long and two short dashes line, simultaneously. It is to be noted that, also in a case in which such pieces of information are not displayed simultaneously but are displayed switchably, a frame visual attribute similar to that of the frame of the window in which the corresponding content is displayed can be set to the frame. 
     Example of Configuration of ACR Service Utilization System 
       FIG. 3  shows an example of a configuration of the ACR service utilization system of the embodiment of the present disclosure. 
     This ACR service utilization system  10  identifies more than one piece of content displayed simultaneously on the screens of the multi-window screen devices  40 - 1  and  40 - 2  such as a TV receiver having a large-sized screen and presents metadata relating to the pieces of content to the user through the second screen device  50  or executes a linked application in conformity with the progression of the content. In the following description, in the case where there is no necessity to individually distinguish the multi-window screen devices  40 - 1  and  40 - 2  from each other, each of them is referred to merely as multi-window screen device  40 . 
     Here, a piece of content is not limited to a program being broadcast. In particular, all AV content such as, for example, a program recorded and reproduced by an external apparatus such as a video recorder connected to the multi-window screen device  40 , a video of a cinema or the like reproduced from a package medium, and a moving picture and music downloaded through the Internet or the like are included in the content. Also a commercial message (hereinafter referred to as CM) inserted between programs or midway of a program is included in the content. 
     For the identification of a piece of content, the ACR service is utilized in which signature data (for example, a watermark or a fingerprint) extracted periodically from the piece of content being viewed and representative of a characteristic of the piece of content is compared with signature data of pieces of content registered in a database in advance to identify the piece of content. 
     The ACR service utilization system  10  is configured from a provider system  20  on the side which supplies-content and a linked application and so forth corresponding to the content, and a home network system  30  on the user side who views content or utilizes a linked application. 
     The provider system  20  and the home network system  30  are connected to each other through a broadcasting network  11  and a bidirectional communication network  12 . Here, the broadcasting network  11  includes a TV broadcasting network, a CATV network, an IPTV network and so forth. The bidirectional communication network  12  is an IP communication network represented by the Internet. 
     It is to be noted that lines between the multi-window screen device  40 - 2  belonging to the home network system  30  and the provider system  20  through the broadcasting network  11  and the bidirectional communication network  12  are omitted. 
     Description of Provider System  20   
     The provider system  20  is configured from a content, server  21 , a metadata server  22 , an application server  23  and an ACR server  24 . 
     The content, server  21  broadcasts content such as a program or a CM through the broadcasting network  11 . Further, the content server  21  supplies content to be broadcast to the ACR server  24 . It is to be noted that, in place of supplying content, a content identifier and signature data extracted in advance from the content may be supplied to the ACR server  24 . 
     The metadata server  22  supplies metadata corresponding to content broadcast from the content server  21  to the ACR server  24 . The metadata includes various kinds of information relating to the content, an identifier representative of a linked application to be executed in accordance with the progression of the content, data to be used in the linked application and so forth. 
     The application server  23  supplies an application and data to be utilized in the application through the bidirectional communication network  12  in accordance with a request from the second screen device  50  of the home network system  30 . 
     The ACR server  24  generates in advance ACR reference data in which a content identifier, an application identifier and so forth are coordinated with signature data extracted in a predetermined sampling period from various pieces of content which can be viewed on the multi-window screen device  40  of the home network system  30  to form a database and retains the database. The ACR server  24  generates an ACR response in response to an ACR query transmitted from any of ACR clients  42 A to  42 C of the multi-window screen device  40  based on the database of the ACR reference data, and transmits the ACR response. 
     It is to be noted that the content server  21 , metadata server  22 , application server  23  and ACR server  24  which configure the provider system  20  may be disposed in a concentrated manner at one place or may be disposed separately in a decentralized fashion. Or some of the components may be combined suitably. Further, a plural number of servers may be provided for each of the component servers. 
     Description of Home Network System  30   
     The home network system  30  is configured from the multi-window screen device  40  such as a TV receiver having a large-sized screen, and the second screen device  50  such as a tablet type terminal, a slate PC or a smartphone. The multi-window screen device  40  and the second screen device  50  are connected to each other, for example, by a wireless LAN. 
     It is to be noted that a plurality of such multi-window screen devices  40  and a plurality of such second screen devices  50  may be provided in the home network system  30 . 
     The multi-window screen device  40  provides a plurality of windows on the screen thereof and displays different pieces of content simultaneously in the windows so as to be viewed by the user. The multi-window screen device  40  includes a content renderer  41 , an ACR client  42 , a UPnP (Universal Plug and Play) server  43 , a local Web server  44 , and a window manager  45 . A number of such content renderers  41  and a number of such ACR clients  42  equal to the number of windows which can be set by the multi-window screen device  40  are incorporated. 
     In the present embodiment, it is assumed that the multi-window screen device  40  can provide three windows A, B and C on the screen thereof. In this instance, it is assumed that three content renders  41 A,  41 B and  41 C and three ACR clients  42 A,  42 B and  42 C are incorporated correspondingly. The number of windows which can be set is not limited to three. In the following description, where there is no necessity to individually distinguish the content renders  41 A,  41 B and  41 C from one another, each of them is referred to simply as content renderer  41 . This similarly applies also to the ACR clients  42 A,  42 B and  42 C. 
     The content renderer  41 A acquires and branches all pieces of content to be displayed in the window A on the screen of the multi-window screen device  40  and supplies the pieces of content to the ACR client  42 A. In particular, the content renderer  41 A acquires and branches not only content broadcast from the content server  21  but also content inputted through various input terminals (HDMI terminal and so forth) of the multi-window screen device  40  and supplies the acquired content to the ACR client  42 A. This similarly applies also to the content renderers  41 B and  41 C. 
     The ACR client  42 A extracts, from content inputted thereto from the content renderer  41 A, signature data representative of a characteristic of the content in a predetermined sampling period. Here, as the extraction method of signature data, an extraction method same as that used by the ACR server  24  of the provider system  20  (hereinafter described) is used. 
     Further, the ACR client  42 A generates an ACR query including the extracted signature data and transmits the ACR query to the ACR server  24  of the provider system  20  through the bidirectional communication network  12 . 
     Further, the ACR client  42 A receives and retains an ACR response transmitted thereto from the ACR server  24  in response to the ACR query transmitted therefrom. This similarly applies also to the ACR clients  42 B and  42 C. 
     The UPnP server  43  universally notifies an other device (in the present case, the second screen device  50 ), which configures the home network system  30  together with the multi-window screen device  40 , of details of a WebAPI (Web Application Program Interface) adapted to call a function of the multi-window screen device  40  (in the present case, to utilize the ACR service by the ACR client  42 ) in which the UPnP server  43  itself is incorporated. In particular, the UPnP server  43  newly defines a protocol on a basic protocol provided by a general UPnP server and uses the defined protocol to carry out universal notification (hereinafter described in detail). 
     The local Web server  44  allows an other device (in the present case, the second screen device  50 ) which configures the home network system  30  together with the multi-window screen device  40  to utilize a function of the multi-window screen device  40  (in the present case, in the present case, to utilize the ACR service by the ACR client  42 ) in which the local Web server  44  itself is incorporated. In particular, the local Web server  44  controls the ACR client  42  in response to the fact that the WebAPI let known from the UPnP server  43  is called to utilize the ACR service, and transfers an ACR response transmitted back from the ACR server  24  to the second screen device  50 . 
     The window manager  45  controls display of a frame of the windows provided on the screen of the multi-window screen device  40 . 
     The second screen device  50  presents, in the present embodiment, metadata of content being viewed principally on the multi-window screen device  40  to the user or executes a linked application in accordance with the progression of the content. The second screen device  50  includes a plurality of ACR applications  51 , a number of linked application managers  52  equal to the number of ACR applications  51 , and a window manager  53 . 
     In the present embodiment, it is assumed that the second screen device  50  includes three ACR applications  51   a ,  51   b  and  51   c  and three linked application managers  52   a ,  52   b  and  52   c . However, the number of them is not limited to three. In the following description, where there is no necessity to individually distinguish the ACR applications  51   a ,  51   b  and  51   c , each of them is referred to merely as ACR application  51 . This similarly applies also to the linked application managers  52   a ,  52   b  and  52   c.    
     The ACR application  51  is installed in advance in the second screen device  50  and is started up when the ACR service is utilized in a linked relationship with the multi-window screen device  40 . The ACR application  51  acquires a WebAPI adapted to read out a function which uses the ACR service from the UPnP server  43  and calls the WebAPI to acquire an ACR response from the ACR server  24  received by the ACR client  42  through the local Web server  44 . Furthermore, the ACR application  51  analyzes the acquired ACR response and notifies the linked application manager  52  of a result of the analysis. 
     The linked application manager  52  presents, in accordance with a notification from the ACR application  51 , metadata included in the ACR response to the user or acquires and executes a linked application corresponding to the content being viewed on the multi-window screen device  40  from the application server  23  through the bidirectional communication network  12 . It is to be noted that a Web browser can be used as the linked application manager  52 . 
     The window manager  53  carries out setting, to the frame which displays information (screen image of metadata or a linked application) displayed by each of the linked application managers  52 , same as the setting of the frame visual attribute of the window of the multi-window screen device  40  in which the corresponding content is displayed. 
     Example of Detailed Configuration of ACR Server  24   
       FIG. 4  shows an example of a detailed configuration of the ACR server  24  included in the provider system  20 . 
     The ACR server  24  is configured from a content acquisition section  61 , a signature extraction section  62 , an ACR database (DB)  63 , an ACR response generation section  64 , and a communication section  65 . 
     The content acquisition section  61  acquires content, which the content server  21  is scheduled to broadcast through the broadcasting network  11 , or various pieces of content, which can be viewed on the multi-window screen device  40 , from the content server  21  or the like and supplies the acquired content to the signature extraction section  62 . The signature extraction section  62  extracts, from the content supplied thereto from the content acquisition section  61 , signature data representative of a characteristic of the content in a predetermined sampling period using a predetermined extraction method and outputs the signature data to the ACR database  63 . 
     To the extraction method of signature data by the signature extraction section  62 , an existing arbitrary method can be applied. For example, a watermark embedded in advance in content may be extracted and used as signature data, or a fingerprint may be calculated and used as signature data. 
     If a fingerprint is used as signature data, then even if the resolution, aspect ratio, bit rate, encoding format or the like of content is converted, the same signature data can be obtained before and after the conversion. Accordingly, the identification accuracy when identification of content is carried out based on the signature data can be enhanced. 
     It is to be noted that, where a plurality of ACR servers  24  are involved, the same extraction method of signature data by the signature extraction section  62  need not be used by the individual ACR servers  24 , but an arbitrary extraction method can be adopted for each of the ACR servers  24 . 
     The ACR database  63  generates and stores ACR reference data in which a content identifier or the like representative of a piece of content of an extraction source from which each signature data is extracted is associated with each signature data inputted from the signature extraction section  62 . Consequently, the signature data extracted from the content are converted into a database. The data structure of ACR reference data is hereinafter described with reference to  FIG. 4 . 
     The ACR response generation section  64  refers to the ACR database  63  to identify a piece of content of an extraction source of signature data included in an ACR query transmitted thereto from the ACR client  42 . Further, the ACR response generation section  64  generates an ACR response which includes the content identifier as a result of the identification, associated metadata and so forth. The data structure of the ACR response is hereinafter described with reference to  FIGS. 8A and 8B . The communication section  65  receives an ACR query transmitted thereto from the ACR client  42  and outputs the ACR query to the ACR response generation section  64 , and transmits an ACR response generated by the ACR response generation section  64  to the ACR client  42 . 
     Example of Detailed Configuration of ACR Client  42   
       FIG. 5  shows an example of a detailed configuration of the ACR client  42  incorporated in the multi-window screen device  40 . 
     The ACR client  42  is configured from a signature extraction section  71 , an ACR query generation section  72 , a communication section  73 , and an ACR response retention section  74 . 
     The signature extraction section  71  extracts, from content branched and supplied from the content renderer  41 , signature data representative of a characteristic of the content in a predetermined sampling period and outputs the signature data to the ACR query generation section  72 . It is to be noted that the extraction method of signature data by the signature extraction section  71  is common to that by the signature extraction section  62  of the ACR server  24  to be utilized. 
     The ACR query generation section  72  generates an ACR query which includes signature data extracted by the signature extraction section  71  and is used to request the ACR server  24  to identify content. The data structure of the ACR query is hereinafter described with reference to  FIG. 7 . 
     The communication section  73  transmits an ACR query generated by the ACR query generation section  72  to the ACR server  24 , receives an ACR response transmitted thereto from the ACR server  24  and outputs the received ACR response to the ACR response retention section  74 . The ACR response retention section  74  retains the ACR response received by the communication section  73 . It is to be noted that the retained ACR response is transferred to the second screen device  50  by the local Web server  44 . 
     Data Structure of ACR Reference Data 
       FIG. 6  illustrates a data structure of ACR reference data formed as a database in the ACR database  63  of the ACR server  24 . 
     In ACR reference data  100 , a content identifier  102 , reproduction time  103  and related metadata  104  are associated with each signature data  101  extracted in a predetermined cycle from content. 
     The signature data  101  is extracted from content by the signature extraction section  62 . The content identifier  102  is information representative of a piece of content of an extraction source of the signature data  101 . The reproduction time  103  indicates progression timing of a piece of content represented by the content identifier  102  at a time at which the signature data  101  is extracted from the content, and is represented, for example, by an elapsed period of time from the top of the piece of content. 
     The related metadata  104  includes metadata of a piece of content represented by the content identifier  102 , a linked application identifier (information uniquely representing a linked application to be executed in accordance with the progression timing of a piece of content indicated by the reproduction time  103 ) and various data to be utilized by the executed linked application. 
     It is to be noted that the related metadata  104  may have contents which differ depending upon the progression timing of a piece of content indicated by the reproduction time  103 . 
     Data Structure of ACR Query 
       FIG. 7  illustrates a data structure of an ACR query generated by the ACR query generation section  72  of the ACR client  42 . 
     An ACR query  110  includes an ACR query identifier  111 , a signature type identifier  112 , a service identifier  113 , signature data  114 , a local timestamp  115 , a source address  116  and a signature  117 . 
     The ACR query identifier  111  is information used to uniquely specify the ACR query  110 . The signature type identifier  112  is information used to specify an extraction method used when the signature data  114  is extracted. The service identifier  113  is information used to select, where a plurality of ACR servers  24  exist, one of the ACR servers  24  to which the ACR query  110  is to be transmitted to obtain an ACR response. 
     The signature data  114  is extracted from content by the signature extraction section  71  of the ACR client  42 . The local timestamp  115  indicates a timing at which the signature data  114  is extracted from the content and is represented by time indicated by a local system clock of the multi-window screen device  40 . 
     The source address  116  is an address of the ACR client  42 , which originates the ACR query  110 , in the bidirectional communication network  12 , and is utilized as information representative of a transmission designation of an ACR response generated by the ACR server  24  in response to the ACR query  110 . The signature  117  suppresses falsification of the ACR query  110 . It is to be noted that the ACR query  110  may be transmitted after it is encoded fully. 
     Data Structure of ACR Response 
       FIGS. 8A and 8B  illustrate data structures of an ACR response generated by the ACR response generation section  64 . 
     An ACR response  120  has a data structure illustrated in  FIG. 8A  or SB.  FIG. 8A  illustrates a data structure of the ACR response  120  in the case where a piece of content of an extraction source of the signature data  114  included in the ACR query  110  is identified successfully, namely, in the case where the user of the multi-window screen device  40  successfully identifies the piece of content being viewed.  FIG. 8B  illustrates a data structure of the ACR response  120  in the case where the piece of content is not identified successfully. 
     In the ACR response  120  ( FIG. 8A ) in the case where the user of the multi-window screen device  40  successfully identifies the piece of content being viewed, an ACR query identifier  121 , a signature type identifier  122 , a service identifier  123 , a content identifier  124 , a reproduction time  125 , a local timestamp  126 , related metadata  127 , a source address  128  and a signature  129  are included. 
     Meanwhile, in the ACR response  120  ( FIG. 8B ) in the case where the user of the multi-window screen device  40  does not successfully identify the piece of content being viewed, the ACR query identifier  121 , the service identifier  122 , the source address  128 , the signature  129  and an identification failure flag  130  are included. 
     The ACR query identifier  121 , signature type identifier  122 , service identifier  123  and local timestamp  126  are used to specify the ACR query  110  which requests transmission of the ACR response  120 , and the ACR query identifier  111 , signature type identifier  112 , service identifier  113  and local timestamp  115  of the ACR query  110  are cited and described. 
     The content identifier  124 , reproduction time  125  and related metadata  127  represent a result of identification of content, and the content identifier  102 , reproduction time  103  and related metadata  104  of the corresponding ACR reference data  100  are cited and described. 
     The source address  128  is an address of the ACR server  24 , which transmits the ACR response  120 , in the bidirectional communication network  12 . The signature  129  is used to suppress falsification of the ACR response  120 . It is to be noted that the ACR response  120  may be entirely encrypted and transmitted to prevent falsification thereof. 
     The identification failure flag  130  is a flag representing failure by the ACR server  24  in identification of a piece of content of an extraction source of the signature data  114  included in the ACR query  110  from the ACR client  42 , namely, of a piece of content being viewed by the user of the multi-window screen device  40 . 
     Process of Home Network System  30  of ACR Service Utilization System  10   
     Now, two different processes when the second screen device  50  in the home network system  30  acquires a device description which is information relating to functions which can be utilized by the multi-window screen device  40  are described. 
     It is to be noted that the functions which can be utilized by the multi-window screen device  40  in the present embodiment indicate utilization of the ACR service by the ACR client  42  and application of a frame visual attribute to each window on the screen by the window manager  45 . 
       FIG. 9  is a flow chart illustrating processing in the case where, in a state in which the ACR application  51  is started up already in the second screen device  50 , the multi-window screen device  40  is connected to the network system  30  (including also the timing at which the multi-window screen device  40  is started up). 
     At step S 1 , the UPnP server  43  of the multi-window screen device  40  multicast distributes a Notify message defined by the UPnP given below to the home network system  30 . The Notify message is transferred to the home network system  30  using a UDP/IP and received, in the present case, by the ACR application  51  of the second screen device  50 . 
     NOTIFY*HTTP/1.1 . . . 
     LOCATION “http://192.168.0.4:55500”. . . 
     In the LOCATION header of the Notify message, an acquisition destination address of a device description of the multi-window screen device  40  is described. Therefore, at step S 11 , the ACR application  51  of the second screen device  50  acquires the device description from the acquisition destination address using a HTTP GET. 
     By the process described above, the ACR application  51  of the second screen device  50  can acquire the device description of the multi-window screen device  40 . 
       FIG. 10  is a flow chart illustrating a process when the ACR application  51  is started up in the second screen device  50  later in a state in which the multi-window screen device  40  has already been connected to the network system  30  and started up. 
     In this instance, since multicast distribution of the Notify message by the UPnP server  43  of the multi-window screen device  40  has been carried out already, the ACR application  51  of the second screen device  50  cannot receive the Notify message. Therefore, at step S 21 , the ACR application  51  searches ACR clients which can be utilized by an M-Search defined by the UPnP. 
     The UPnP server  43  of the multi-window screen device  40  responding to the M-Search answers the device description at step S 31 . The ACR application  51  receives the device description at step S 22 . 
     By the process described above, the ACR application  51  of the second screen device  50  can acquire the device description of the multi-window screen device  40 . 
     Example of Device Description 
     Here, an example of the device description is described. In order to describe a device description, for 
     example, an XML file is used. 
     A first example of the device description is described below. 
     First example of the device description 
     
       
         
           
               
               
             
               
                   
               
             
            
               
                   
                 &lt;root xmlns=“urn:schemas-upnp-org:device-1-0”&gt;  
               
               
                   
                 . . . 
               
               
                   
                 &lt;serviceList&gt;  
               
               
                   
                   &lt;service&gt;  
               
               
                   
                    &lt;serviceType&gt;“ urn:abc:service:ACRClient.v1” &lt;/service  
               
               
                   
                 Type&gt; (signifies ACR client service)  
               
               
                   
                    &lt;serviceId&gt;“ urn:UPnP:serviceId:1234”&lt;/serviceId&gt;  
               
               
                   
                 (signifies service ID of ACR client service)  
               
               
                   
                    &lt;SCPDURL&gt;&lt;/SCPDURL&gt;  
               
               
                   
                    &lt;controlUrL&gt;“ http://192.168.0.4:55500/getACRResponse”  
               
               
                   
                 &lt;/controlURL&gt;  
               
               
                   
                    &lt;WindowStyle&gt;“http://192.168.0.4:55500/windowStyle”  
               
               
                   
                 &lt;/WindowStyle&gt;  
               
               
                   
                   . . .  
               
               
                   
                   &lt;/service&gt;  
               
               
                   
                  &lt;/serviceList&gt;  
               
               
                   
                 . . .  
               
               
                   
                 &lt;/root&gt;  
               
               
                   
               
            
           
         
       
     
     It is to be noted that, in a &lt;SCPDURL&gt; element of a device description prescribed in an existing general UPnP, an acquisition destination address of a service description described in regard to ACR services which can be utilized by the ACR client  42  is described, and the ACR application  51  acquires the service description from the acquisition destination address using the HTTP GET. Further, the ACR application  51  sends a message of an action to a URL described in a &lt;controlURL&gt; element using a SOAP prescribed in the UPnP to call the action (in the present case, transmission of an ACR query and transfer of an ACR response). 
     However, in the present embodiment, in order to make it possible to call an action by a reduced number of steps, such a device description prescribed in the UPnP as described above is expanded such that the WebAPI adapted to call the action is described directly in the device description. 
     In particular, as in the case of the first example described hereinabove, for example, the &lt;SCPDURL&gt; element is left empty with nothing described therein, or else a predetermined dummy character string is described in the &lt;SCPDURL&gt; element while a server side script URL (in the case of the first example, http://192.168.0.4:55500/getACRResponse) of the WebAPI adapted to start up the ACR client and request transfer of the ACR response  120  is described directly in the &lt;controlURL&gt; element. 
     Further, a &lt;WindowStyle&gt; element which is not described in the UPnP is provided newly such that a server side script URL (in the case of the first example, http://192.168.0.4:55500/widowStyle) of the WebAPI adapted to notify the window manager  45  of a frame visual attribute or change the frame visual attribute is described directly in the &lt;WindowStyle&gt; element. 
     It is to be noted that a &lt;service&gt; element is described for each of the installed ACR clients  42 . Accordingly, in the case of the present embodiment, three &lt;service&gt; elements are described in a &lt;serviceList&gt;. 
     Or, a &lt;WebAPIURL&gt; element which is not prescribed by the UPnP may be provided newly such that a server side script URL of the WebAPI is described directly in the &lt;WebAPIURL&gt; element, as in the case of a second example described below. 
     Second example of the device description 
     
       
         
           
               
               
             
               
                   
               
             
            
               
                   
                 &lt;root xmlns=“urn:schemas-upnp-org:device-1-0”&gt; 
               
               
                   
                 . . .  
               
               
                   
                 &lt;serviceList&gt;  
               
               
                   
                   &lt;service&gt;  
               
               
                   
                    &lt;serviceType&gt;“ urn:abc:service:ACRClient.v1” &lt;/service 
               
               
                   
                 Type&gt; (signifies ACR client service)  
               
               
                   
                    &lt;serviceId&gt;“ urn:UPnP:serviceId:1234” &lt;/serviceId&gt;  
               
               
                   
                 (signifies service ID of ACR client service)  
               
               
                   
                    &lt;SCPDURL&gt;&lt;/SCPDURL&gt;  
               
               
                   
                    &lt;controlURL&gt;&lt;/controlURL&gt;  
               
               
                   
                    &lt;WebAPIURL&gt;“ http://192.168.0.4:55500/getACRResponse” 
               
               
                   
                 &lt;/WebAPIURL&gt;  
               
               
                   
                   &lt;WindowStyle&gt;“http://192.168.0.4:55500/windowStyle” 
               
               
                   
                 &lt;/WindowStyle&gt;  
               
               
                   
                   . . . 
               
               
                   
                   &lt;/service&gt;  
               
               
                   
                  &lt;/serviceList&gt;  
               
               
                   
               
            
           
         
       
     
     The ACR application  51  of the second screen device  50  which has acquired the device description of the first or second example can cause an action to be executed by calling the getACRResponse which is the server side script url of the WebAPI described in the &lt;controlURL&gt; element or the &lt;WebAPIDRL&gt; element of the device description using the HTTP GET. 
     In particular, it is possible to start up, if the ACR client  42  of the multi-window screen device  40  is not started up as yet, the ACR client  42 , cause the ACR client  42  to transmit the ACR query  110 , and transfer the ACR response  120  sent back in response to the ACR query  110 . It is to be noted that the transfer of the ACR response  120  is carried out in a state in which it is described in the body of an HTTP response returned in response to the WebAPI, for example, in the following manner using a JSON.
     HTTP/1.1 200 OK   Content-Type: application/json; charset=utf-8   . . .   

     “Contents of ACR response encoded by JSON” 
     A transaction which uses the WebAPI is carried out by repetitive polling while content is being viewed. Then, in response to the progression of the content, the related metadata  127  and so forth in the ACR response  120  converted currently are presented to the user through the second screen device  50 . 
     If the device description is expanded and standardized as described above, then the multi-window screen device  4   0  and the second screen device  50  which are fabricated and sold by different vendors can rapidly operate in a linked relationship with each other. 
     It is to be noted that, a WebSocket whose standardization is formulated by the IETF (Internet Engineering Task Force) and so forth may be used in place of use of the Web API. Where the WebSocket is used, a WebSocket server is provided in the local Web server  44  (or the ACR client  42  or second screen device  50 ) such that a session (TCP connection) establishment request is issued from both of the ACR application  51  and the ACR client  42  through the WebSocket server to establish a session and the ACR response  120  is transferred on the session using the JSON described hereinabove or the like. 
     In this instance, if the ACR client  42  receives a new ACR response  120  from the ACR server  24 , then the ACR response  120  is transferred immediately to the ACR application  51  through the established session. Accordingly, the necessity for polling which is necessitated where the WebAPI is used is eliminated, and immediate transfer of the ACR response  120  which does not rely upon the period of polling becomes possible. 
     Further, the ACR application  51  can acquire a frame visual attribute of a window provided on the screen of the multi-window screen device  40  from the window manager  45  through the local Web server  44  by calling a windowStyle, which is the server side script url of the WebAPI described in the &lt;WindowStyle&gt; element of the device description by the HTTP GET. 
     In particular, a frame visual attribute is described in the body of an HTTP response returned in response to the WebAPI, For example, if a color is set as a frame visual attribute, then 
     border-color:#ffa000−&gt; example of designating an orange border color
 
is described in the body of the HTTP response.
 
     It is to be noted that, if the frame visual attribute returned from the multi-window screen device  40 - 1  and the frame visual attribute returned from the multi-window screen device  40 - 2  overlap with each other, then it is possible to request one of the multi-window screen devices  40 - 1  and  40 - 2  to change the frame visual attribute. 
     In particular, a frame visual attribute into which the frame visual attribute is to be changed may be described into the body of a request by a HTTP POST request to the URL of the WebAPI of the &lt;WindowStyle&gt;element. The following example indicates a case in which an overlapping frame visual attribute is changed to (border-color:# ffa001). 
     POST/windowStyle HTTP/1.0 
     host: 192.168.0.4:55500 
     Content-Length: 20 
     border-color:#ffa001 
     Operation by ACR Service Utilization System  10   
     Now, operation of the ACR service utilization system  10  is described. 
     It is to be noted that, as a prerequisite of operation described below, it is assumed that, in the home network system  30 , the ACR application  51  of the second screen device  50  has already acquired, a device description from the UPnP server  43  of the multi-window screen device  40 . 
     Further, it is assumed that, in the ACR server  24  of the provider system  20 , ACR reference data  100  corresponding to various pieces of content which can be viewed on the multi-window screen device  40  have been generated and are registered in the ACR database  63 . 
       FIG. 11  is a flow chart illustrating operation of the ACR service utilization system  10 . 
     At step S 41 , the content server  21  of the provider system  20  starts transmission of content through the broadcasting network  11 . 
     On the other hand, in the home network system  30 , the multi-window screen device  40  starts reception and reproduction of the content at step S 51 . Here, if the ACR application  51  of the second screen device  50  calls the WebAPI which requests startup of the ACR client  42  and transfer of an ACR response at step S 61 , then the ACR client  42  and so forth start operation under the control of the local Web server  44  in response to the WebAPI. 
     In particular, if the ACR client  42  of the multi-window screen device  40  receives supply of a piece of content which is being viewed from the content renderer  41 , then the signature extraction section  71  extracts the signature data  114  from the piece of content and outputs the signature data  114  to the ACPI query generation section  72  at step S 52 . At step S 53 , the ACR query generation section  72  generates an ACR query  110  which includes the signature data  114 , and the communication section  73  transmits the generated ACR query  110  to the ACR server  24 . 
     In the ACR server  24  which receives the ACR query  110  from the ACPI client  42 , the ACR response generation section  64  refers to the ACR database  63  to identify a piece of content corresponding to the signature data  114  included in the received ACR query  110  at step S 42 . Further, the ACR response generation section  64  generates an ACR response  120  in response to a result of the identification of the piece of content and the communication section  65  transmits the generated ACR response  120  to the ACR client  42  at step S 43 . 
     The ACR client  42  which receives the ACR response  120  from the ACR server  24  supplies the received ACR response  120  to the local Web server  44  at step S 54 . The local Web server  44  transfers the ACR response  120  to the ACR application  51  of the second screen device  50 . 
     In the ACR application  51  which receives the ACR response  120  transferred thereto, the ACR application  51  of the second screen device  50  calls the WebAPI used to request notification of a frame visual attribute at step S 62 . In response to this, the local Web server  44  notifies the ACR application  51  of the frame visual attribute managed by the window manager  45  at step S 55 . 
     The ACR application  51  which receives the notification of the frame visual attribute notifies the window manager  53  of the frame visual attribute. The window manager  53  confirms whether or not the received frame visual attribute overlaps with the frame visual attribute notified already from an other multi-window screen device  40 . If an overlapping is detected, then the ACR application  51  requests change of the frame visual attribute by an HTTP POST request. The request is transmitted from the local Web server  44  to the window manager  45  at step S 56 . If the window manager  45  changes the frame visual attribute in accordance with the request, then the frame visual attribute after the change is conveyed as a notification from, the local Web server  44  to the ACR application  51 . The ACR application  51  which receives the frame visual attribute after the change notifies the window manager  53  of the frame visual attribute after the change at step S 64 . The window manager  53  sets the frame visual attribute of a screen image of a linked application to be displayed thereafter and the like based on the frame visual attribute after the change. 
     It is to be noted that, if it is confirmed at step S 62  that the frame visual attribute does not overlap, then a change of the frame visual attribute is not requested, and the process at step S 64  is executed. 
     Further, the processes at steps S 62  to S 64  may be executed immediately after the process at step S 61  without waiting for the process at step S 54  (transfer of an ACR response). 
     At step S 65 , the ACR application  51  analyzes the related metadata  127  included in the ACR response  120  transferred thereto and causes the linked application manager  52  to acquire a linked application to be executed in conformity with the progression of the piece of content being viewed. 
     At step S 66 , the linked application manager  52  acquires and executes the linked application supplied by the process at step S 44  by the application server  23 , It is to be noted that, if the linked application has been acquired already, then the acquisition can be omitted. Further, if the linked application has already been started up, then the startup of the linked application can be omitted. Furthermore, information included in the related metadata  127  is sometimes presented to the user without involving execution of the linked application. 
     At this time, the frame of the screen image of the linked application presented to the user has the frame visual attribute coinciding with the frame visual attribute of the frame of the window in which the corresponding piece of content is displayed on the multi-window screen device  40 . 
     The processes at steps S 41  to S 44 , processes at steps S 51  to S 56  and processes at steps S 61  to  66  described above are executed repetitively while the content is viewed. However, it is possible to omit the repetitions or reduce the frequency in execution of the processes at steps S 61  to S 66  and the processes at steps S 55  and S 56 . 
     Consequently, the second screen device  50  can operate the linked application in accordance with the progression of a piece of content being viewed on the multi-window screen device  40  by the user. 
     Further, the user can quickly grasp to which one of pieces of content displayed on the multi-window screen device  40  the screen image presented to the user by the second screen device  50  corresponds. 
     Incidentally, while it is possible to configure the servers from the content server  21  to ACR server  24  of the provider system  20  and the multi-window screen device  40  and second screen device  50  of the home network system  30 , which execute the series of processes described above individually by hardware, they may otherwise be implemented by a computer executing software. This computer includes a computer incorporated in hardware for exclusive use, a personal computer, for example, for universal use which can execute various functions by installing various programs, and so forth. 
       FIG. 12  is a block diagram showing an example of a hardware configuration of the computer described above. 
     In a computer  200 , a CPU (Central Processing Unit)  201 , a ROM (Read Only Memory)  202  and a RAM (Random Access Memory)  203  are connected to one another by a bus  204 . 
     Further, an input/output interface  205  is connected to the bus  204 . An inputting section  206 , an output ting section  207 , a storage section  208 , a communication section  209  and a drive  220  are connected to the input/output interface  205 . 
     The inputting section  206  is configured from a keyboard, a mouse, a microphone and so forth. The outputting section  207  is configured from a display unit, a speaker and so forth. The storage section  208  is configured from a hard disk, a nonvolatile memory or the like. The communication section  209  is configured from a network interface and so forth. The drive  220  drives a removable medium  211  such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory. 
     In the computer  200  configured in such a manner as described above, the CPU  201  loads a program stored, for example, in the storage section  208  into the RAM  203  through the input/output interface  205  and the bus  204  and executes the program to carry out the series of processes described above. 
     The program to be executed by the; computer  200  (CPU  201 ) can be recorded on and provided as the removable medium  211  as a package medium, for example. Further, the program can be provided through a wire or wireless transmission medium such as a local area network, the Internet or a digital satellite broadcast. 
     In the computer  200 , the program can be installed into the storage section  208  through the input/output interface  205  by loading the removable medium  211  into the drive  220 . Further, the program can be received by the communication section  209  through a wire or wireless transmission medium and installed into the storage section  208 . Otherwise, the program can be installed in advance in the ROM  202  or the storage section  208 . 
     It is to be noted that the program to be executed by the computer  200  may be a program by which the processes are carried out in a time series in the order-as described in the present specification or a program by which the processes are executed in parallel or at necessary timings such as when the processes are called. 
     It is to be noted that the embodiment of the present disclosure is not limited to the specific embodiment described hereinabove but can foe changed in various manners without departing from the subject matter of the present disclosure.