Abstract:
The present invention relates to a method for providing an interoperable digital rights management system for content data on a client based on synchronization technology, the method comprising the steps of:—receiving of a selection of content data from the, client,—generating of an XML file having a defined DTD format, the XML file comprising license information and a locator for the content data,—sending of the XML file to the client, synchronizing any license status relates data produced on the client back to the server.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to the field of providing content data to a client, and more particularly without limitation to the management of digital license rights.  
       BACKGROUND AND PRIOR ART  
       [0002]     The digital representation of media content combined with computing and networking technologies provides a powerful way to publish. According to this relatively new mode of publishing, networking technology permits the delivery of digitized media content over a network such as the Internet to end user client computers. Communication protocols define how the digitized media content is exchanged over the network. A media player runs on the end user client computer to allow the user to render the media content.  
         [0003]     Digital rights management is a central issue in the on-line commercialization of digital media content data. Digital media content data can promise of video and audio data, images, documents, software and other forms of digital content.  
         [0004]     The usual property of digital content is that the publisher (or re-seller) gives or sells the content to a client, but continues to restrict rights to use the content even after the content is under the sole physical control of the client. For instance, a publisher will typically retain copyright to a work so that the client cannot reproduce or publish the work without permission.  
         [0005]     A publisher could also adjust pricing according to whether the client is allowed to make a persistent copy, or is just allowed to view the content on-line as it is delivered. These scenarios reveal a peculiar arrangement. The user that possesses the digital content data often does not have full rights to their use; instead, the provider retains at least some of the rights.  
         [0006]     A variety of digital rights management systems and methods are known from the prior art which are used to enforce that usage of the content data by the client is within the scope of the license the user has obtained from the publisher.  
         [0007]     U.S. Pat. No. 6,330,670 shows a digital rights management operating system which protects rights-managed data, such as downloaded content, from access by untrusted programs while the data is loaded into memory or on a page file as a result of the execution of a trusted application that accesses the memory. To protect the rights-managed data resident in memory, the digital rights management operating system refuses to load an untrusted program into memory while the trusted application is executing or removes the data from memory before loading the untrusted program. This way unauthorised copying of the rights-managed data can be prevented.  
         [0008]     U.S. Patent applications 2002/0013772A1 and U.S. 2002/0108049A1 show further digital rights management systems.  
         [0009]     Windows® Media Rights Manager® is an end-to-end digital rights management (DRM) system which is commercially available from Microsoft. This system offers content providers and retailers a flexible platform for the secure distribution of digital media files. It lets content providers deliver songs, videos, and other digital media content over the Internet in a protected, encrypted file format and it helps protect digital media (such as songs and videos) by packaging digital media files.  
         [0010]     A packaged media file contains a version of a media file that has been encrypted and locked with a key. This packaged file is also bundled with additional information from the content provider. The result is a packaged media file that can only be played by a person who has obtained a license.  
         [0011]     One of the problems of digital rights management is that different publishers and content providers use different digital rights management methods. A client device therefore needs to support multiple digital rights management methods to enable a user to obtain and render content data from publishers using different kinds of digital rights management methods.  
         [0012]     Another problem related to prior art digital rights management systems is that no renewal of a license can be obtained when the client device is off-line. For example the user has purchased a license which enables him or her to play back the content data a fixed amount of times. When the user is travelling and no network connection is available he or she may use up the acquired license so that no more play back is possible. In this instance the user needs to wait until he or she can reconnect the client device to the network for renewal of the licence.  
         [0013]     The present invention therefore aims to provide an improved method for providing content data to a client as well as a corresponding computer program and computer system.  
       SUMMARY OF THE INVENTION  
       [0014]     The invention provides for a method for providing of content data to a client which enables usage of multiple digital rights management systems in a generic way. This is accomplished by means of using an XML based document for the exchange of data based on a document type definition (DTD) which defines a format of interchanging digital rights management data independently from a particular digital rights management system a publisher uses. When the user has purchased a license the corresponding digital rights management data, i.e. the license information, is provided to the client device of the user in the form of an extended markup language (XML) file having the defined DTD format. The client device parses the XML file in order to extract the license information and stores the license information locally. Further the client device uses the locator contained in the XML file to download the content data. The content could also be directly included in the document, depending on the size of it. A rendering application on the client device, such as a windows media player, may then be used to render the content data which has been downloaded.  
         [0015]     In accordance with a preferred embodiment of the invention the rendering application checks with the common license client of the client device for license status information. If the desired rendering of the content data is covered by the actual license status the rendering can start and the license status is adapted correspondingly. When the license has expired playback is disabled. The use of the license is recorded by the common licence client in the local database.  
         [0016]     In accordance with a further preferred embodiment of the invention playback is not disabled when the license has expired but usage of the content data after expiration of the license is tracked and stored in the local license database. When the client device is re-connected to a network a process is started in order to retroactively pay for the required license rights. This way the user is enabled to still play back content data when the original license has expired and the user has no access to a network connection while travelling. In particular, this enables subscription based business models.  
         [0017]     Further preferred embodiments of the present invention are set forth in the dependent claims. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]     In the following preferred embodiments of the invention will be described in greater detail by making reference to the drawings in which:  
         [0019]      FIG. 1  is a block diagram of an embodiment of a computer system of the invention,  
         [0020]      FIG. 2  is an example of an XML file having a defined DTD format for communicating license information to a client device,  
         [0021]      FIG. 3  is a block diagram of a preferred embodiment of a client device in accordance with the invention,  
         [0022]      FIG. 4  is illustrative of a flow diagram of an embodiment of a method of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0023]      FIG. 1  shows a block diagram of a computer system  100 . The computer system  100  has a server computer  102  which implements a web-portal  104 . Web-portal  104  provides a platform for the selection of digital content data and purchase of license rights for the usage of such digital content data.  
         [0024]     Server computer  102  has content selection database  106  which is coupled to web-portal  104  in order to enable a user to perform database queries for the user&#39;s identification and selection of desired content data, such as music, video, images, software or other digital media content data.  
         [0025]     The client computer  108  can be coupled to server computer  102  via a computer network, such as the Internet or a wireless network. By means of client computer  108  a user can select content data from the web-portal  104 , purchase and pay for licenses and receive digital rights management data, i.e. license information, in the form of an XML file in DTD format. Client computer  108  can be a personal computer, a personal digital assistant, a mobile telephone or another stationary or portable device which can be connected to server computer  102  over a computer network.  
         [0026]     Server computer  102  can be coupled to license server  110 . License server  110  has license database  112  in which the license conditions of publishers and other providers of digital media content data are stored. Server computer  102  can request such license conditions from license server  110  which queries license database  112  to return the license conditions of a particular digital media content data file to server computer  102 .  
         [0027]     The digital media content data is stored in content database  116  of content server  114 . Client computer  108  can request downloading of a desired content data file from content server  114 ; it needs to provide a corresponding license key in order to enable the download operation.  
         [0028]     The preferred embodiment considered here is particularly advantageous in that a variety of digital rights management methods can be used by server computer  102  without a requirement that client computer  108  supports the exact same digital rights management method. The reason for this kind of flexibility is that the defined DTD format provides a generic and common way for interchanging of digital rights management data. Irrespective of the particular digital rights methodology which is used by server computer  102 , client computer  108  can parse the XML file in the DTD format in order to extract the required digital rights management information and protect the content data accordingly.  
         [0029]     For details of the DTD grammar reference is made to the XML specification (http://www.w3.org/TR/REC-xml) which is incorporated herein by reference in its entirety.  
         [0030]      FIG. 2  shows an example of an XML file in a pre-defined DTD format which is sent from server computer  102  to client computer  108 . Line  200  of the DTD file indicates the ‘source’, i.e. the content provider which distributes the license information, such as the URL (uniform resource locator) for accessing content database  116  on content server  114 . In the example considered here this URL is ‘www.songsforsale.com’.  
         [0031]     Line  202  of the DTD file provides an indication of the ‘target’, i.e. a reference to the local rendering application which uses the licensing information. In the example considered here this is the MP3player/video1 rendering application on the client computer  108 .  
         [0032]     Line  204  indicates the type and/or the format of the embedded license information. In other words line  204  indicates the digital rights management method which is to be used. In the example considered here this is ‘MSFTMediaRightManager’.  
         [0033]     Line  206  of the DTD file indicates an identifier (ID) of the licensed content data item. By means of this key the ‘source’ can unambiguously identify the content data. In this example the ID is ‘10536681’.  
         [0034]     Line  208  of the DTD file indicates license information, such as a key required for downloading of the content data or the key required to execute the file on the client, data indicating the scope of the license, i.e. a fixed number of allowed playbacks or a certain duration. Further state information can be included here such as used/unused, valid/expired, . . .  
         [0035]     This can be followed by another line  208  indicating such license information for another content data item with another ID given in a subsequent line  206 .  
         [0036]      FIG. 3  shows a more detailed block diagram of client computer  108 . Client computer  108  has a program module for interfacing of client computer  108  with server computer  102  over a computer network. Program module  300  has a parser  302  for parsing of an XML file in DTD format which has been received from server computer  102  (cf.  FIG. 1 ). Further program module  300  has content download module  304  for requesting download of content data and receiving the content data.  
         [0037]     Client computer  108  has a local license database  308  for storing of license information which has been extracted by means of parser  302  from the XML file.  
         [0038]     Content data which has been downloaded is stored in local content database  310 . Rendering application program  312  can access local content database  300  through common license client  311  for rendering of content data by means of output device  314 , such as a speaker or a display. Further client computer  108  has a user interface  316  through which a user can select a content data file from the local content database  310  for rendering by the rendering application  312 .  
         [0039]     In operation client computer  108  receives an XML file in DTD format from server computer  102  (cf.  FIG. 1 ). The XML file is parsed by parser  302  of program module  300 . The license information data extracted by parser  302  from the XML file is stored in local license database  308 . The content data is downloaded by means of content download module  304  from the content server (cf.  FIG. 1 ) or can be contained in the same XML document (depending on the size).  
         [0040]     The downloaded content data is stored in local content database  310  for later rendering by rendering application  312 .  
         [0041]     The user can select a particular content data file via user interface  316  for playback. A corresponding request is entered from the user interface  316  into rendering application  312 . In response rendering application  312  requests the common license client to check the license status of the requested content data in local license database  308 . If the license status is sufficient for playback the content data is returned by the common license client by retrieving it from the local content database  310  and rendered by rendering application  312 . If the license status is insufficient for rendering, rendering is disabled.  
         [0042]     The digital rights management method indicated in the XML file may allow that a user continues to use the content data even after the original license has been exhausted provided that the amount of usage of the content data after expiration of the original license is tracked and stored by the common license client  311  in local license database  308  for later payment. If such a digital rights management method is specified for the requested content data in local license database  308  application program  312  still renders the content data and stores the amount of usage of the content data in the local license database  308 . When the client computer  108  is re-connected to the network license a synchronization of entries which have been made in local license database  308  is performed by means of synchronization module  307  and renewal module  306  is started to renew the license and provide payment for the amount of usage of the content data after expiration of the original license.  
         [0043]     This way license renewal module  306  implements an automatic process for renewal of a license which has been previously purchased. Synchronization module  307  can be based on any synchronization technique, such as SyncML.  
         [0044]     It is to be noted that a variety of further rendering application programs can be installed. These rendering application programs rely on the common license client  311  for obtaining and updating license status related data.  
         [0045]      FIG. 4  is illustrative of a corresponding method. In step  400  a selection of content data is made by means of a client on a web-portal. In step  402  the web-portal requests the license conditions for the selected content data from a license server computer and offers corresponding license options to the client. In step  404  the client selects a certain license type and provides payment in step  406  by inputting of a payment identifier, such as a credit card number.  
         [0046]     In step  408  the web-portal generates an XML file in a pre-defined DTD format containing the license information.  
         [0047]     The XML file is transmitted to the client.  
         [0048]     In step  410  the client parses the XML file and stores the extracted license information in its local license database in step  412 . In step  414  the content data is downloaded by the client by means of the license information contained in the XML file and stored in its local content database. In step  416  a user selects certain content data which has been downloaded for rendering. In response a corresponding rendering application program checks the license status of the content data to be rendered in step  418 .  
         [0049]     Depending on the license status rendering is started in step  420 . In step  422  the rendering application program updates the license information stored in the local license database by calling the common license client API. For example if the license encompasses the fixed number of playbacks of the content data the remaining number of playbacks is decremented accordingly by the common license client. When the license has been used up renewal of the license is requested in step  424  from the client.  
         [0050]     A corresponding request is sent to the web-portal and an additional XML file is received by the client for renewal of the license. This renewal of the license can be performed in response to a corresponding request of the user or it can be triggered automatically when the original license has expired depending on the settings which have been chosen by the user.  
       LIST OF REFERENCE NUMERALS  
       [0051]    
       
         
               
               
               
             
           
               
                   
                   
               
               
                   
                   
               
             
             
               
                   
                 computer system 
                 100 
               
               
                   
                 server computer 
                 102 
               
               
                   
                 web-portal 
                 104 
               
               
                   
                 consistent selection database 
                 106 
               
               
                   
                 client computer 
                 108 
               
               
                   
                 license server 
                 110 
               
               
                   
                 license database 
                 112 
               
               
                   
                 content server 
                 114 
               
               
                   
                 content database 
                 116 
               
               
                   
                 line 
                 200 
               
               
                   
                 line 
                 202 
               
               
                   
                 line 
                 204 
               
               
                   
                 line 
                 206 
               
               
                   
                 line 
                 208 
               
               
                   
                 program module 
                 300 
               
               
                   
                 parser 
                 302 
               
               
                   
                 content download module 
                 304 
               
               
                   
                 license renewal module 
                 306 
               
               
                   
                 synchronization module 
                 307 
               
               
                   
                 local license database 
                 308 
               
               
                   
                 local content database 
                 310 
               
               
                   
                 common license client 
                 311 
               
               
                   
                 rendering application 
                 312 
               
               
                   
                 output device 
                 314 
               
               
                   
                 user interface 
                 316