The .NET 4 Framework makes it easier for developers to work with services from their managed code applications. With .NET 4, the WCF technology provides several different types of services to start from, based on your particular needs, but they all share the same underlying infrastructure.
Here’s how the pieces align:
· SOAP Services – Allows full flexibility for building operation-centric services. This includes industry standard interoperability, as well as channel and host plug-ability. Use this for operation-based services which need to do things such as interoperability with Java, be consumed by multiple clients, flow transactions, use message based security, use transports or channels in addition to HTTP, or host in processes outside of IIS.
· WebHttp Services – Best when you are exposing operation-centric HTTP services to be deployed at web scale or are building a RESTful service and want full control over the URI/format/protocol. Support for HTTP services was added to WCF in .NET Framework 3.5 and generally referred to as “WCF REST”. A number of significant improvements, such as content negotiation have been added in .NET Framework 4.
· Data Services –Data Services are best when you are exposing your data model and associated logic through a RESTful interface; it includes a full implementation of the Open Data (OData) Protocol for .NET (more on this below) to make this process very easy. . WCF Data Services was originally released as ‘ADO.NET Data Services’ with the release of .NET Framework 3.5 SP1;
· Workflow Services – Is best for long running, durable operations or where the specification and enforcement of operation sequencing is important. Workflow services are implemented using Windows Workflow Foundation (WF) activities that can make use of WCF for sending and receiving WCF-based service requests.
· RIA Services – is best for building an end-to-end Silverlight application. WCF RIA services will be released with Silverlight 4, and is built upon WCF.
Check-out this blog post from The .NET Endpoint for the full story: http://blogs.msdn.com/endpoint/archive/2010/01/04/wcf-data-services-ria-services-alignment-questions-and-answers.aspx