ADO.NET Data Services

ADO.NET Data Services (codename "Astoria") [cite web | url = http://blogs.msdn.com/data/archive/2007/12/10/ado-net-data-services-ctp-released.aspx | title = ADO.NET Data Services CTP Released! | accessdate = 2007-11-12] is a platform for what Microsoft calls "Data Services". It is actually a combination of the runtime and a web service through which the services are exposed. In addition, it also includes the Data Services Toolkit which lets Astoria Data Services be created from within ASP.NET itself. The Astoria project was announced at MIX 2007, and the first developer preview was made available on April 30, 2007. The first CTP was made available as a part of the ASP.NET 3.5 Extensions Preview. The final version was released as part of Service Pack 1 of the .NET Framework 3.5 on August 11 2008.

Overview

ADO.NET Data Services exposes data, represented as Entity Data Model (EDM) objects, via web services accessed over HTTP. The data can be addressed using a REST-like URI. The Astoria service, when accessed via the HTTP GET method with such a URI, will return the data. The web service can be configured to return the data in either plain XML, JSON or RDF+XML. In the initial release, formats like RSS and ATOM are not supported, though they may be in the future. In addition, using other HTTP methods like PUT, POST or DELETE, the data can be updated as well. POST can be used to create new entities, PUT for updating an entity, and DELETE for deleting an entity.

The URIs representing the data will contain the physical location of the service, as well as the service name. In addition, it will also need to specify an EDM Entity-Set or a specific entity instance, as in respectively http://dataserver/service.svc/MusicCollectionor http://dataserver/service.svs/MusicCollection [SomeArtist] The former will list all entities in the "Collection" set whereas the latter will list only for the entity which is indexed by "SomeArtist".

In addition, the URIs can also specify a traversal of a relationship in the Entity Data Model. For example, http://dataserver/service.svs/MusicCollection [SomeSong] /Genretraverses the relationship "Genre" (in SQL parlance, joins with the "Genre" table) and retrieves all instances of "Genre" that are associated with the entity "SomeSong". Simple predicates can also be specified in the URI, like http://dataserver/service.svs/MusicCollection [SomeArtist] /ReleaseDate [Year eq 2006] will fetch the items that are indexed by "SomeArtist" and had their "release" in "2006". Filtering and partition informationcan also be encoded in the URL as http://dataserver/service.svs/MusicCollection?$orderby=ReleaseDate&$skip=100&$take=50

References

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* [http://astoria.mslivelabs.com/Overview.doc Microsoft Codename "Astoria" Overview]

External links

* [http://msdn.microsoft.com/en-us/library/cc907912.aspx Using Microsoft ADO.NET Data Services]
* [http://www.asp.net/downloads/3.5-extensions/ ASP.NET 3.5 Extensions Preview]
* [http://blogs.msdn.com/astoriateam/ ADO.NET Data Services (Project Astoria) Team Blog]
* [http://entmag.com/news/article.asp?EditorialsID=9105 Access Cloud Data with Astoria: ENT News Online]