Using Microsoft Entity Frameworks to Access Progress Schema Objects with Virtuoso
This document details the steps required to provide Microsoft Entity Framework access to Progress Schema Objects using the OpenLink Virtuoso Universal Server. This is achieved by Linking the required Progress 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 Progress Schema objects linked into the Virtuoso Server.
- Prerequisites
- Progress/OE 10
- ODBC Driver for Progress (SQL-92)
- Virtuoso 5.10.x or later
- Microsoft Visual Studio 2008 SP1 or later
- Tasks
- Ensure Progress Primary Keys (PKs) are not NULLable
- Install and configure ODBC Driver for Progress (SQL-92)
- Install and configure Virtuoso
- Link Progress tables into Virtuoso
- Create a Visual Studio Entity Data Model (EDM)
- Use the EDM to create Entity Framework applications
Prerequisites
Progress/OE 10
A Progress DBMS hosting the required Schema Objects needs to be available.
In this document, the isports sample database will be used to demonstrate the process.
ODBC Driver for Progress (SQL-92)
A Progress ODBC Driver is required to link the Progress Schema Objects into the Virtuoso Server.
The OpenLink ODBC Driver for Progress (SQL-92) will be used in this document, for which a functional ODBC Data source name of prs101c will be assumed to exist on the machine hosting the Virtuoso Server.
Virtuoso 5.10.x or later
An OpenLink Virtuoso Universal Server installation including the Virtuoso Universal Server and ADO.NET Entity Framework Provider is required. The Virtuoso components must be Release 5.10.x or above, this being the minimum version containing support for Microsoft Entity Frameworks. We recommend using the latest Virtuoso component versions currently available.
Microsoft Visual Studio 2008 SP1 or later
Microsoft Visual Studio 2008 with Service Pack 1 or later is required, this being the earliest version containing the necessary Entity Framework support.
Tasks
Ensure Progress Primary Keys (PKs) are not NULLable
The Visual Studio 2008 Entity Data Model (EDM) requires that all primary keys are NOT NULLable. Visual Studio 2008 will fail to generate an EDM, if any primary keys are nullable. Therefore, ensure that any applicable primary keys are defined as not nullable in the Progress database schema before attempting to generate an EDM.
It seems that, by default, several Primary Keys (PKs) in the isports database allows <NULL> values. It seems somewhat nonsensical — that a unique key whose sole purpose is to identify rows in tables can be allowed to be <NULL>.
This issue is best addressed directly in the database schema, by redefining those PKs that allow <NULL> so as not to allow <NULL>. Progress does not seem to talk in terms of <NULL>. Instead, it uses the term Mandatory.
The following document will provide more specific details about how to ensure Progress PKs are not nullable —
- Ensuring Progress PKs are not nullable
Install and configure ODBC Driver for Progress (SQL-92)
The Virtuoso Virtual Database engine uses ODBC as the connectivity mechanism for linking remote database objects into its local schema. Thus, a Progress ODBC Driver must be available with a suitably configured DSN for connecting to the target database. The OpenLink ODBC Drivers for Progress have been used in this document, although in theory any Progress ODBC Driver can be used.
Installation instructions for the OpenLink ODBC Driver for Progress are available from:
Install and configure Virtuoso
Link Progress tables into Virtuoso
Create a Visual Studio Entity Data Model (EDM)
In the event that no entity-linking associations are automatically created (as is the case here with Progress), the associations will need to be created manually.
The following document details this process —
Use the EDM to create Entity Framework applications
Now that a Microsoft Entity Data Model has been created for the Progress isports database, Entity Framework applications can be created to make use of it.
