Microsoft’s vision for .NET is a wide one. In addition to their desire for it to support all programming languages, either directly or through interoperability layers, they also want to bring together all communication frameworks and data storage engines. While WCF is making headway for standardizing communication APIs, their universal data access model Entity Framework is lagging behind.
A major problem up until now is that the ADO.NET Entity Framework did not come with out of the box support for the major non-Microsoft databases such as Oracle. This has opened a door for third-party vendors to fill in the gaps.
Once such vendor is Data Direct. For many users their most important claim to fame is being 100% managed code. Usually that isn’t really a big deal, but in this case it means that you can completely avoid the Oracle client.
Another vendor is Devart. Devart’s offering has been on the scene a bit longer than Data Direct and offers a comparable feature list. And not surprisingly, not needing the Oracle client is number 1 on their feature list as well.
Oracle itself is strangely quiet on the matter. While Oracle does offer ODP.NET, it is limited to the standard ADO.NET design patterns.