Device Description Repository
Encyclopedia
The Device Description Repository (DDR) is a concept proposed by the Mobile Web Initiative
Device Description Working Group
(DDWG) of the World Wide Web Consortium
. The DDR is supported by a standard interface and an initial core vocabulary of device properties. Implementations of the proposed repository are expected to contain information about Web-enabled devices (particularly mobile devices). Authors of Web content will be able to make use of repositories to adapt their content to best suit the requesting device. This will facilitate the interaction and viewing of Web pages across devices with widely varying capabilities.
Information in a repository should include information such as the screen dimensions, input mechanisms, supported colors, known limitations, special capabilities etc.
The "DDR Core Vocabulary" was published in April 2008. It illustrates how to create definitions of properties that can be used in conjunction with the DDR Simple API.
The "DDR Simple API" specification was published as a W3C Recommendation
in December 2008.
The DDWG formally closed in December 2008. The Chair and volunteers agreed to maintain the DDWG home page and wiki after this time, to answer questions and encourage implementations.
The interface to the repository should provide the means of retrieving contextual information based on some evidence that identifies the context. Typically this means providing request headers through the interface and subsequently retrieving values for named properties. The W3C DDWG
produced an initial vocabulary of such properties (based on a formal ontology), and an interface for the retrieval functionality. The interface is designed in a language-neutral manner to enable many implementations on many platforms. The published specification includes samples in Java, IDL and WSDL.
On the 4th of November 2011 during Mobile2Days event the OpenDDR project was launched. It is a open source project aiming to be the reference community implementation of W3C's DDR Simple API and the reference community repository.
Mobile Web
The Mobile Web refers to the use of Internet-connected applications, or browser-based access to the Internet from a mobile device, such as a smartphone or tablet computer, connected to a wireless network....
Device Description Working Group
W3C Device Description Working Group
The W3C Device Description Working Group , operating as part of the World Wide Web Consortium Mobile Web Initiative , was chartered to "foster the provision and access to device descriptions that can be used in support of Web-enabled applications that provide an appropriate user experience on...
(DDWG) of the World Wide Web Consortium
World Wide Web Consortium
The World Wide Web Consortium is the main international standards organization for the World Wide Web .Founded and headed by Tim Berners-Lee, the consortium is made up of member organizations which maintain full-time staff for the purpose of working together in the development of standards for the...
. The DDR is supported by a standard interface and an initial core vocabulary of device properties. Implementations of the proposed repository are expected to contain information about Web-enabled devices (particularly mobile devices). Authors of Web content will be able to make use of repositories to adapt their content to best suit the requesting device. This will facilitate the interaction and viewing of Web pages across devices with widely varying capabilities.
Information in a repository should include information such as the screen dimensions, input mechanisms, supported colors, known limitations, special capabilities etc.
Status
The "requirements for a single logical device descriptions repository" were first published as a W3C Working Draft in April 2006, and completed as a "Working Group Note" in December 2007.The "DDR Core Vocabulary" was published in April 2008. It illustrates how to create definitions of properties that can be used in conjunction with the DDR Simple API.
The "DDR Simple API" specification was published as a W3C Recommendation
W3C recommendation
A W3C Recommendation is the final stage of a ratification process of the World Wide Web Consortium working group concerning a technical standard. This designation signifies that a document has been subjected to a public and W3C-member organization's review. It aims to standardise the Web technology...
in December 2008.
The DDWG formally closed in December 2008. The Chair and volunteers agreed to maintain the DDWG home page and wiki after this time, to answer questions and encourage implementations.
Background
The idea of implementing a Device Description Repository was discussed at an international workshop held by the DDWG in Madrid, Spain in July, 2006. This resulted in a proposal to re-charter DDWG to work on the formal design of the programming interfaces, and ways to populate a repository with data and make this available to anyone who wanted to build Web servers that could adapt content to suit the end user devices.Design goals
The architecture of the repository was not prescribed, but distributed solution are likely. In general, the desirable characteristics of a Device Description Repository are:- Relevance of data. The DDWGW3C Device Description Working GroupThe W3C Device Description Working Group , operating as part of the World Wide Web Consortium Mobile Web Initiative , was chartered to "foster the provision and access to device descriptions that can be used in support of Web-enabled applications that provide an appropriate user experience on...
includes content adaptation specialists who have identified a core set of device properties that are useful for adaptation. Other groups are likely to refine this knowledge. Keeping the information up-to-date will also be a challenge. - Ease of use. The interfaces should map easily to a variety of programming languages, and be as simple to use as other popular adaptation technologies (e.g. WURFLWurflWURFL stands for Wireless Universal Resource FiLe. It is a community effort focused on mobile device detection: the problem of presenting content on the wide variety of wireless devices. WURFL is a set of proprietary API's and an XML configuration file which contains information about device...
or OpenDDR). - Ease of deployment. Existing technologies like DNSDomain name systemThe Domain Name System is a hierarchical distributed naming system for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities...
show that global repositories can be deployed on a real-time basis. The W3C is unlikely to specify a particular server architecture. The DDWG has already identified a Web Service interface (e.g. SOAPSOAPSOAP, originally defined as Simple Object Access Protocol, is a protocol specification for exchanging structured information in the implementation of Web Services in computer networks...
) as a minimum requirement, and implementations are free to create the logic any way they wish (e.g. relational database queries) so long as the formal interface is supported. - Assured interoperability. The varied nature of the Web requires that the repository interfaces and data formats can be supported by the largest number of Web technologies. Formal descriptions of APIs and Data Vocabularies will be necessary.
- Assured availability. If Web servers rely on device descriptions to provide adapted content, then these descriptions must be available at all times. Multiple repository hosts and support for data caching are likely to be part of the repository architecture.
- Efficiency. To ensure that the repository does not create unnecessary burden on scarce resources, the load should be distributed and data formats should be designed for simple processing.
- Industry support. The backing of organisations like W3C and the Open Mobile AllianceOpen Mobile AllianceThe Open Mobile Alliance is a standards body which develops open standards for the mobile phone industry.- Principles :Mission: To provide interoperable service enablers working across countries, operators and mobile terminals....
, and of vendors, service providers and device manufacturers will be critical.
The interface to the repository should provide the means of retrieving contextual information based on some evidence that identifies the context. Typically this means providing request headers through the interface and subsequently retrieving values for named properties. The W3C DDWG
W3C Device Description Working Group
The W3C Device Description Working Group , operating as part of the World Wide Web Consortium Mobile Web Initiative , was chartered to "foster the provision and access to device descriptions that can be used in support of Web-enabled applications that provide an appropriate user experience on...
produced an initial vocabulary of such properties (based on a formal ontology), and an interface for the retrieval functionality. The interface is designed in a language-neutral manner to enable many implementations on many platforms. The published specification includes samples in Java, IDL and WSDL.
Implementations
Open and commercial implementations of the DDR Simple API are available. Some of these formed part of the W3C's implementation report prior to the API becoming a Web standard. The W3C's Mobile Web Initiative also tracks implementations of relevant mobile standards and other developer resources, including the DDR Simple API.On the 4th of November 2011 during Mobile2Days event the OpenDDR project was launched. It is a open source project aiming to be the reference community implementation of W3C's DDR Simple API and the reference community repository.
Links
- UAProfUAProfThe UAProf specification is concerned with capturing capability and preference information for wireless devices...
- W3C
- WURFLWurflWURFL stands for Wireless Universal Resource FiLe. It is a community effort focused on mobile device detection: the problem of presenting content on the wide variety of wireless devices. WURFL is a set of proprietary API's and an XML configuration file which contains information about device...
- MyMobileWeb DDR Simple API Implementation
- OpenDDR
- Mobile device detectionMobile device detectionMobile Device Detection refers to software that identifies the type of mobile device visiting a web site and either redirects the end user to a dedicated mobile web site or adapts the format of the web site to suit the end user’s device....