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.
中文版：
Microsoft对.NET的定义很广泛。除了支持所有的编程语言，不管是直接还是通过互操作，微软还希望能集成所有的通信框架和数据存储引擎。当WCF已经在标准化通信API的道路上取得领先时，微软的通用数据访问模型Entity Framework却落在了后面。
迄今为止，ADO.NET Entity Framework的主要问题是不支持非微软的主流数据库，例如Oracle。这为第三方厂商提供了机会。
其中一个就是Data Direct。对于大多数用户来说，他们提供的最重要的特性就是100%的托管代码实现。通常来说，这也并不是什么大不了的事，但在这里却意味着你完全不需要Oracle客户端。
另一家厂商是Devart。他们比Data Direct开始的更早，产品的特性也差不多。意料之中的是，不需要Oracle客户端也是他们最重要的特性。
与此同时，Oracle自己却显得异常沉寂。虽然Oracle也提供了ODP.NET，但是它只支持标准的ADO.NET。