WCF Contarcts

 A contract is a agreement between two or more parties for common understanding and it is a is a platform-neutral and standard way of describing what the service does. In WCF, all services expose contracts.
1) Operation Contract: An operation contract defines the parameters and return type of an operation.

[OperationContract] double Add(double i, double j);

2) Service Contract: Ties together multiple related operations contracts into a single functional unit. [ServiceContract] //System.ServiceModel public interface IMath { [OperationContract] double Add(double i, double j); [OperationContract] double Sub(double i, double j); [OperationContract] Complex AddComplexNo(Complex i, Complex j); [OperationContract] Complex SubComplexNo(Complex i, Complex j); } 3) Data Contract: The descriptions in metadata of the data types that a service uses. [DataContract] //using System.Runtime.Serialization public class Complex { private int real; private int imaginary; [DataMember] public int Real { get; set; } [DataMember] public int Imaginary { get; set; } }