How to implement MessageContract in WCF?

Question

Okay this is the scenario !! I know I am definitely making some mistakes but I want to clear out the basics and I want to implement them successfully. I have an Employee class which is a DataContract in WCF and FullTimeEmployee and PartTimeEmployee extend the class. In my EmployeeService we return the objects of FullTimeEmployee and PartTimeEmployee based on user inputs respectively from a console application client( Only in Demo purpose ). Now I want to tweak the SOAP messages by MessgaeContract. I want the request object to be called EmployeeRequestObject and the response object the EmployeeResponseObject and I want to include same license Keys in their headers.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.Text;

namespace EmployeeServiceLibrary
{
[ServiceContract]
public interface IEmployeeService
{
    [OperationContract]
    EmployeeResponse GetEmployee(EmployeeRequest request);
}

#region EmployeeRequestObject

[MessageContract(IsWrapped=true,WrapperName="EmployeeRequestObject",WrapperNamespace="http://Chiranjib_VAIO.com/")]
public class EmployeeRequest
{
    [MessageBodyMember(Namespace = "http://Chiranjib_VAIO.com/")]
    public int EmployeeRequestID { get; set; }

    [MessageHeader(Namespace = "http://Chiranjib_VAIO.com/")]
    public string EmployeeRequestLicenseKey { get; set; }
}
#endregion

#region EmployeeResponseObject
public class EmployeeResponse
{
    public EmployeeResponse()
    {
    }

    public EmployeeResponse(EmployeeRequest e)
    {
        this.EmployeeResponseLicenseKey = e.EmployeeRequestLicenseKey+"_Response";
    }

    [MessageHeader(Namespace = "http://Chiranjib_VAIO.com/")]
    public string EmployeeResponseLicenseKey { get; set; }
}
#endregion

[KnownType(typeof(FullTimeEmployee))]
[KnownType(typeof(PartTimeEmployee))]
[DataContract]
public abstract class Employee
{
    [DataMember]
    public int EmployeeId { get; set; }

    [DataMember]
    public string Name { get; set; }

    [DataMember]
    public string Gender { get; set; }

    [DataMember]
    public EmployeeType EmpType { get; set; }
}

public enum EmployeeType
{
    FullTimeEmployee=0,
    PartTimeEmployee=1
}

[DataContract]
public class FullTimeEmployee : Employee
{
    [DataMember]
    public decimal AnnualSalary { get; set; }
}

[DataContract]
public class PartTimeEmployee : Employee
{
    [DataMember]
    public int HoursWorked { get; set; }

    [DataMember]
    public decimal SalaryPerHour { get; set; }
}
}

When User inputs a 0 I want a FullTimeEmployee Object to be returned and when inputs a 1 I want a PartTimeEmployee Object to be returned. Here is the Service file

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.Text;

namespace EmployeeServiceLibrary
{
public class EmployeeService : IEmployeeService
{
    public EmployeeResponse GetEmployee(EmployeeRequest request)
    {
        int empId = request.EmployeeRequestID;
        switch (empId)
        {
            case 0:
                return new FullTimeEmployee()
                {
                    EmployeeId=1,
                    Name="Chiranjib Nandy",
                    Gender="Male",
                    EmpType=EmployeeType.FullTimeEmployee,
                    AnnualSalary=1500
                };
            case 1:
                return new PartTimeEmployee()
                {
                    EmployeeId = 1,
                    Name = "Archana Nandy",
                    Gender = "Female",
                    EmpType = EmployeeType.PartTimeEmployee,
                    HoursWorked=9,
                    SalaryPerHour=150
                };
            default: return null;
        }
    }
}

}

But the error is saying cannot implicitly convert EmployeeServiceLibrary.FullTimeEmployee to EmployeeServiceLibrary.EmployeeResponse. How to achieve the desired behavior ? Helps are badly appreciated !! Thanks

Answer 1

Your code wont compile, as both your return types implement Employee , not EmployeeResponse . You can encapsulate a Employee object inside your EmployeeResponse

public class EmployeeResponse
{
   public EmployeeResponse(EmployeeRequest e)
   {
       this.EmployeeResponseLicenseKey = e.EmployeeRequestLicenseKey+"_Response";
   }

   [MessageHeader(Namespace = "http://Chiranjib_VAIO.com/")]
   public string EmployeeResponseLicenseKey { get; set; }

   public Employee Employee { get; set; }
}

And then modify your code to:

public EmployeeResponse GetEmployee(EmployeeRequest request)
{
    int empId = request.EmployeeRequestID;
    switch (empId)
    {
        case 0:
            return new EmployeeResponse
            {
               Employee = new FullTimeEmployee()
               {
                 EmployeeId=1,
                 Name="Chiranjib Nandy",
                 Gender="Male",
                 EmpType=EmployeeType.FullTimeEmployee,
                 AnnualSalary=1500
               }
            }
        case 1:
            return new EmployeeResponse
            {
               Employee = new PartTimeEmployee()
               {
                  EmployeeId = 1,
                  Name = "Archana Nandy",
                  Gender = "Female",
                  EmpType = EmployeeType.PartTimeEmployee,
                  HoursWorked=9,
                  SalaryPerHour=150
               }
            }

        default: return null;
}