Abstract

This section details the steps required to provide Microsoft Entity Framework access to Oracle Schema Objects using the OpenLink Virtuoso Universal Server. This is achieved by linking the required Oracle 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 Oracle Schema objects linked into the Virtuoso Server.

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

Oracle DBMS.  An Oracle DBMS hosting the required Schema Objects needs to be available. In this section the Oracle Human Resources sample database will be used to demonstrate the process.

An Oracle DBMS hosting the required Schema Objects needs to be available. In this section the Oracle Human Resources sample database will be used to demonstrate the process.

ODBC Driver for Oracle.  An Oracle ODBC Driver is required for Linking the Oracle Schema Objects into the Virtuoso Server. The OpenLink ODBC Driver for Oracle will be used in this section, for which a functional ODBC Data source name of "ora10ma" will be assumed to exist on the machine hosting the Virtuoso Server.

An Oracle ODBC Driver is required for Linking the Oracle Schema Objects into the Virtuoso Server. The OpenLink ODBC Driver for Oracle will be used in this section, for which a functional ODBC Data source name of "ora10ma" 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

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.

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 Oracle 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 Oracle database schema before attempting to generate an EDM. In the case of the Oracle Human Resources database all tables are not nullable, thus this should not be an issue in this case.

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 Oracle database schema before attempting to generate an EDM. In the case of the Oracle Human Resources database all tables are not nullable, thus this should not be an issue in this case.