1.WS* Protocols
WCF can implement the WS* protocols by using a binding called WsHttpBinding.This binding makes use of some of the WS* protocols and adds the needs behaviors,such as transactional message calls,reliability,discovery,and addressing.
2.WSDL
WSDL is a XML-formatted definition of the contract. It contains all metadata for the interface of the service including function names, parameter names, and their types and the types of return values. The purpose of a WSDL file is to define this contract in a cross-platform way as the types are expressed in XML types.
3.Contract-First Principle
Remember that services are black boxes;
4.Atomic Service Transactions
WCF supports transactions by implementing the WS-Atomic Transaction(WS-AT) protocol. Most often transactions on the service level to transactions on the database level.