Using Microsoft Entity Frameworks to Access Microsoft SQL Server Schema Objects with Virtuoso

This document details the steps required to provide Microsoft Entity Framework access to Microsoft SQL Server Schema Objects using the OpenLink Virtuoso Universal Server. This is achieved by linking the required Microsoft SQL Server Schema objects into Virtuoso using its built in Virtual Database engine, and then using the Virtuoso ADO.NET Entity Framework provider to query the remote Microsoft SQL Server Schema objects linked into the Virtuoso Server.

Prerequisites

The following prerequisites must be in place for this solution to be possible.

Microsoft SQL Server DBMS

A Microsoft SQL Server DBMS hosting the required Schema Objects needs to be available. In this document the Microsoft SQL Server Northwind sample database will be used to demonstrate the process.

ODBC Driver for Microsoft SQL Server

A Microsoft SQL Server ODBC Driver is required for Linking the Microsoft SQL Server Schema Objects into the Virtuoso Server. The OpenLink ODBC Driver for Microsoft SQL Server will be used in this document, for which a functional ODBC Data source name of "sql2k5ma" will be assumed to exist on the machine hosting the Virtuoso Server.

Virtuoso Universal Server

An Virtuoso installation including the Virtuoso Universal Server and ADO.NET Entity Framework Provider is required. The Virtuoso components used must be Release 5.10.x or above, this being the minimum version containing support for Microsoft Entity Frameworks.

Microsoft Visual Studio 2008 SP1

Microsoft Visual Studio 2008 Service Pack 1 is required, this being the only version containing the necessary Entity Framework support available at the time of writing.

Tasks

Ensure Microsoft SQL Server Primary Keys (PKs) are not nullable

The Visual Studio 2008 Entity Data Model (EDM) requires that all primary keys are *NOT* Nullable, and will fail to generate an EDM if any are. Thus ensure any tables to be used are defined as not nullable in the Microsoft SQL Server database schema before attempting to generate an EDM. In the case of the Microsoft SQL Server Human Resources database all tables are not nullable, thus this should not be an issue in this case.

Install and configure OpenLink ODBC Driver for Microsoft SQL Server

The Virtuoso Virtual Database engine uses ODBC as the connectivity mechanism for linking remote database objects into its local schema. Thus a Microsoft SQL Server ODBC Driver must be available with a suitably configured DSN for connecting to the target database. The OpenLink ODBC Drivers for MIcrosoft SQL Server have been used in this document, although in theory any Microsoft SQL Server ODBC Driver can be used.

Installation instructions for the OpenLink ODBC Driver for Microsoft SQL Server are available from:

Install and configure OpenLink Virtuoso Universal Server

Linking Microsoft SQL Server tables into Virtuoso

Creating Visual Studio hosted Entity Data Model (EDM)

Using EDM to create Entity Framework based applications

Now that a Microsoft Entity Data Model has been created for the Microsoft SQL Server Northwind database, Entity Framework applications can be created to make use of it.

Entity Frameworks based ADO.NET Data Service
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