Microsoft has published two papers explaining the vision for the future of data access in .NET. The combination of ADO.NET, Entity Framework, and LINQ will mean .NET will finally have real object mapping capabilities not just to relational stores but also between languages and other data formats such as XML. The papers were briefly available in May but then taken down, these new papers are the official release. At the moment, there has not been a CTP for the Entity Framework.
Unlike existing attempts at O/R mapping that define mappings directly between objects and database schema's, Microsoft proposes a new conceptual model that decouples objects (or other data presentation formats) and relational databases:
Unlike existing attempts at O/R mapping that define mappings directly between objects and database schema's, Microsoft proposes a new conceptual model that decouples objects (or other data presentation formats) and relational databases:
The conceptual data model is made real by the creation of an extended relational model, called the entity data model (EDM), that embraces entities and relationships as first class concepts, a query language for the EDM, a comprehensive mapping engine that translates from the conceptual to the logical (relational) level, and a set of model-driven tools that help create entity-object, object-xml, entity-xml transformers. Collectively, all these services are called the Entity Framework. ADO.NET, the Entity Framework, and .NET Language Integrated Query (LINQ) innovations in C# and Visual Basic represent a next-generation data access platform for Microsoft.The papers:
- Next-Generation Data Access - Microsoft's vision to raise the level of abstraction of data access to the conceptual level.
- The ADO.NET Entity Framework Overview
LINQ to SQL has its roots in ObjectSpaces, which was first announced at the PDC in 2001. After PDC03 it was merged with WinFS. It later reappeared as DLinq. The DLinq overview document published in September 2005 was subtitled ".NET Language Integrated Query for Relational Data" and talks at length about creating and querying entity classes. It states "DLinq is part of the ADO.NET family of technologies". In hindsight this is an amazing statement, because it is obvious that at the time the DLinq efforts were totally oblivious to the ADO.NET Entity Framework efforts. And conversely, the ADO.NET vNext efforts seemed oblivous to LINQ by introducing yet another query language called Entity SQL.