What is Message contract in wcf?

Message is a packet of data which contains important information. WCF use this message to transfer from source to destination path.

WCF uses a SOAP message for communication. SOAP message contain message Envelop, Header and body.

Message contract is used to control the structure of a message body and serialization process. It is used to send/access the information over SOAP. Using message contract you can customize the parameter sent using a SOAP message between the client and the server.

How to Define/Declare MessageHeader and MessageBody?

MessageHeader:-
A Message Header is applied to a member of a message contract to declare the member within the message header. 

[MessageContract(IsWrapped = true)]

public class EmpRequest
{

  [MessageHeader(Name = "EmpIdentity")]
  public string EmpId;

}

Message Body:-

A Message Body Member is applied to a member of a message contract to declare the member within the message body.

[MessageContract(IsWrapped = true)]

public class EmpResponse

{

    [MessageBodyMember]

    public Employee EmpINfo;

}

 

 

Example:-

Create WCF Service application.

 

Code for IService.cs :-

using System;

using System.Collections.Generic;

using System.Linq;

using System.Runtime.Serialization;

using System.ServiceModel;

using System.ServiceModel.Web;

using System.Text;

 

// NOTE: You can use the "Rename" command on the "Refactor" menu to change the interface name "IService" in both code and config file together.

[ServiceContract]

public interface IService

{

 

    [OperationContract]

    [FaultContract(typeof(string))]

    EmpResponse GetEmpInfo(EmpRequest request);

 

 

            // TODO: Add your service operations here

}

 

// Use a data contract as illustrated in the sample below to add composite types to service operations.

 

[MessageContract(IsWrapped = true)]

public class EmpRequest

{

    [MessageHeader(Name = "EmpIdentity")]

    public string EmpId;

}

 

[MessageContract(IsWrapped = true)]

public class EmpResponse

{

    [MessageBodyMember]

    public Employee EmpINfo;

}

 

[DataContract]

public class Employee

{

    [DataMember(Name = "FirstName", Order = 1)]

    public string FirstName;

 

    public string firstName

    {

        get { return firstName; }

        set { firstName = value; }

    }

 

    [DataMember(Name = "LastName", Order = 2)]

    public string LastName;

 

    public string lastName

    {

        get { return lastName; }

        set { lastName = value; }

    }

 

    [DataMember(Name = "Address", Order = 3)]

    public string Address;

 

    public string address

    {

        get { return address; }

        set { address = value; }

    }

}

 

Code for Service.cs :-

 

using System;

using System.Collections.Generic;

using System.Linq;

using System.Runtime.Serialization;

using System.ServiceModel;

using System.ServiceModel.Web;

using System.Text;

 

// NOTE: You can use the "Rename" command on the "Refactor" menu to change the class name "Service" in code, svc and config file together.

public class Service : IService

{

            public string GetData(int value)

            {

                        return string.Format("You entered: {0}", value);

            }

            public CompositeType GetDataUsingDataContract(CompositeType composite)

            {

                        if (composite == null)

                        {

                                    throw new ArgumentNullException("composite");

                        }

                        if (composite.BoolValue)

                        {

                                    composite.StringValue += "Suffix";

                        }

                        return composite;

            }

    private const string EmpId = "d2nf@5";

    public EmpResponse GetEmpInfo(EmpRequest request)

    {

        EmpResponse response = new EmpResponse();

 

        if (request.EmpId != EmpId)

        {

            string error = "Invalid Emp Id";

            throw new FaultException<string>(error);

  }

       response.EmpINfo = new Employee();

        response.EmpINfo.firstName = "Sushil";

        response.EmpINfo.lastName = "Modi";

        response.EmpINfo.address = "Bangalore"

        return response;

    }

}

 

Now deploy the Service on IIS or Local Server.

Create one Windows or Console application.

Add service reference into your application.

After adding service reference, create an object of Service Client proxy class and call the GetEmpInfo method and display the Employee info as given below.

class Program

{

static void Main(string[] args)

{

Try

{

   ServiceReference2.ServiceClient ref2 = new ServiceClient();

   ServiceReference2.Author a = ref2.GetAuthorInfo("d2nf@5");

   Console.WriteLine("First Name: " + a.firstName + "\t" + "Last Name" +                a.lastName + "\t" + "Address : " + a.address);

}

 catch (FaultException<string> ex)

 {

   Console.Write(ex.Detail + "<br/>");

 }

}

If you pass wrong EmpId the it show “Invalid Emp Id”.