WCF is based on SOA architecture. Its main objective is to achieve features of SOA and coming as close as possible to it. It is basically a framework for creating and distributing the connected applications. WCF provides the set if classes which provides developer a facility to create a SOA applications.

So do you know what is SOA?

SOA stands for Service oriented architecture, A loosely coupled architecture which seperates the distinct functional units which can be accessible over the nework and users can combine and reuse the in the applications. Following are the four principals of SOA

1) Explicit boundaries – It means services can be accessible freely by other services and can be deployed anywhere regardless of envoirment or development language of the other service.

2) Autonomous Services – As services demand change, it means services are build and deployed independent of other services. Each service must be managed and versioned differently and should not affect the services in the process.

3) Policiy based compatability – This allow service to move from one envoirment to other without changing the behaviour of service. Two services must know each other policies and look for similarites so that they can start communicating. If they can’t satisft each other policies they can’t communicate.

4) Shared schemas and contracts – Schema means data and contracts means behavior. The contract contains the information regarding the structure of message. Services do not pass classes and objects, they passes schemas and contracts.

Few points about SOA :-

1) They are location and platform independet.
2) Services are isolated.
3) Services are protocol, format, and transport neutral. Service communication information is flexible.
4) Services are scalable.
5) They are not constrained. For example if you need to move service you just need to change policy, not the service itself.

Some main features of WCF :-

1) Transactions :- Remember database transactions? example if you have 4 transactions and if one of them fails all four should roll back ye? The same comes in WCF, now you can group the communcations into the transactions.

2) Hosting :- Now services can be hosted with different hosting enviorment, such as Windows NT Services, Windows Forms, and console applications, and well as IIS (Internet Information Services) and Windows Activation Services (WAS).

3) Securtiy :- Enhanced security is provided in WCF. Each and every communication is authenticated. WCF includes message integrity and message confidentiality. WCF also enables your application to integrated intp existing security infrastructure.

4) Queuing. As WCF use MSMQ message transport. Message can be queued and safely stored, providing the consistent state of communcation. Queuing collect and stores the information from sending application and forwards it to recieving application.

So thats all about WCF in brief. WCF is a very useful feature provided by microsoft for service oriented applications.