In simple words contract defines the functionality provides/offers by a service and functionally uses by the client.
Main point to note is: Contract can be completely independent of the implementation of service.
In WCF [Windows Comunication Foundation] can be grouped in following three different contract types:

Data Contract
Describes a data structure.Maps CLR types to XSD. In other words we can say that it defines the Data received by and returned from Service.
Here CLR types are mapped to XML schemas. Data Contract requires explicit marking of the fields that should be serialized with the …

Debugging a WCF Service
Following are the 3-different ways to start debugging a WCF service:

When you are debugging a client process that calls a service. Here debugger steps into the service also service does not have to be in the same solution as your client application.
When you are debugging a client process that requests to a service and here service must be a part of your solution.
When you are using Attach to Process to attach to currently running service. Here debugging begins inside the service.

Debugging with Visual Studio 2008
Using Visual …