Language-Integrated Querying of XML Data in SQL Server

Developers need to access persistent XML data programmatically. Object-oriented access is often the preferred method. Translating XML data into objects or vice-versa is a hard problem due to the data model mismatch and the difficulty of query translation. Our prototype addresses this problem by transforming object-based queries and updates into queries and updates on XML using declarative mappings between classes and XML schema types. Our prototype extends the ADO.NET Entity Framework and leverages its object-relational mapping capabilities. We demonstrate how a developer can interact with stored relational and XML data using the Language Integrated Query (LINQ) feature of .NET. We show how LINQ queries are translated into a combination of SQL and XQuery. Finally, we illustrate how explicit mappings facilitate data independence upon database refactoring.