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How to: Implement a Windows Communication Foundation Service Contract

This is the second of six tasks required to create a basic Windows Communication Foundation (WCF) service and a client that can call the service. For an overview of all six tasks, see the Getting Started Tutorial topic.

The next step in creating a WCF application is to implement the service interface. This involves creating a class called CalculatorService that implements the user-defined ICalculator interface..

To implement a WCF service contract

  • Open the Service1.cs or Service1.vb file and add the following code:

    //Service1.cs
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Runtime.Serialization;
    using System.ServiceModel;
    using System.Text;
    
    namespace GettingStartedLib
    {
        public class CalculatorService : ICalculator
        {
            public double Add(double n1, double n2)
            {
                double result = n1 + n2;
                Console.WriteLine("Received Add({0},{1})", n1, n2);
                // Code added to write output to the console window.
                Console.WriteLine("Return: {0}", result);
                return result;
            }
    
            public double Subtract(double n1, double n2)
            {
                double result = n1 - n2;
                Console.WriteLine("Received Subtract({0},{1})", n1, n2);
                Console.WriteLine("Return: {0}", result);
                return result;
            }
    
            public double Multiply(double n1, double n2)
            {
                double result = n1 * n2;
                Console.WriteLine("Received Multiply({0},{1})", n1, n2);
                Console.WriteLine("Return: {0}", result);
                return result;
            }
    
            public double Divide(double n1, double n2)
            {
                double result = n1 / n2;
                Console.WriteLine("Received Divide({0},{1})", n1, n2);
                Console.WriteLine("Return: {0}", result);
                return result;
            }
        }
    }
    
    
    ‘Service1.vb
    Imports System
    Imports System.ServiceModel
    
    Namespace GettingStartedLib
    
        Public Class CalculatorService
            Implements ICalculator
    
            Public Function Add(ByVal n1 As Double, ByVal n2 As Double) As Double Implements ICalculator.Add
                Dim result As Double = n1 + n2
                ' Code added to write output to the console window.
                Console.WriteLine("Received Add({0},{1})", n1, n2)
                Console.WriteLine("Return: {0}", result)
                Return result
            End Function
    
            Public Function Subtract(ByVal n1 As Double, ByVal n2 As Double) As Double Implements ICalculator.Subtract
                Dim result As Double = n1 - n2
                Console.WriteLine("Received Subtract({0},{1})", n1, n2)
                Console.WriteLine("Return: {0}", result)
                Return result
    
            End Function
    
            Public Function Multiply(ByVal n1 As Double, ByVal n2 As Double) As Double Implements ICalculator.Multiply
                Dim result As Double = n1 * n2
                Console.WriteLine("Received Multiply({0},{1})", n1, n2)
                Console.WriteLine("Return: {0}", result)
                Return result
    
            End Function
    
            Public Function Divide(ByVal n1 As Double, ByVal n2 As Double) As Double Implements ICalculator.Divide
                Dim result As Double = n1 / n2
                Console.WriteLine("Received Divide({0},{1})", n1, n2)
                Console.WriteLine("Return: {0}", result)
                Return result
    
            End Function
        End Class
    End Namespace
    

    Each method implements the calculator operation and writes some text to the console to make testing easier.

The following code shows both the interface that defines the contract and the implementation of the interface.

// IService1.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.Text;

namespace GettingStartedLib
{
        [ServiceContract(Namespace = "http://Microsoft.ServiceModel.Samples")]
        public interface ICalculator
        {
            [OperationContract]
            double Add(double n1, double n2);
            [OperationContract]
            double Subtract(double n1, double n2);
            [OperationContract]
            double Multiply(double n1, double n2);
            [OperationContract]
            double Divide(double n1, double n2);
        }
}

// Service1.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.Text;

namespace GettingStartedLib
{
    public class CalculatorService : ICalculator
    {
        public double Add(double n1, double n2)
        {
            double result = n1 + n2;
            Console.WriteLine("Received Add({0},{1})", n1, n2);
            // Code added to write output to the console window.
            Console.WriteLine("Return: {0}", result);
            return result;
        }

        public double Subtract(double n1, double n2)
        {
            double result = n1 - n2;
            Console.WriteLine("Received Subtract({0},{1})", n1, n2);
            Console.WriteLine("Return: {0}", result);
            return result;
        }

        public double Multiply(double n1, double n2)
        {
            double result = n1 * n2;
            Console.WriteLine("Received Multiply({0},{1})", n1, n2);
            Console.WriteLine("Return: {0}", result);
            return result;
        }

        public double Divide(double n1, double n2)
        {
            double result = n1 / n2;
            Console.WriteLine("Received Divide({0},{1})", n1, n2);
            Console.WriteLine("Return: {0}", result);
            return result;
        }
    }
}

‘IService.vb
Imports System
Imports System.ServiceModel

Namespace GettingStartedLib

    <ServiceContract(Namespace:="http://Microsoft.ServiceModel.Samples")> _
    Public Interface ICalculator

        <OperationContract()> _
        Function Add(ByVal n1 As Double, ByVal n2 As Double) As Double
        <OperationContract()> _
        Function Subtract(ByVal n1 As Double, ByVal n2 As Double) As Double
        <OperationContract()> _
        Function Multiply(ByVal n1 As Double, ByVal n2 As Double) As Double
        <OperationContract()> _
        Function Divide(ByVal n1 As Double, ByVal n2 As Double) As Double
    End Interface
End Namespace
Imports System
Imports System.ServiceModel


Namespace GettingStartedLib

    Public Class CalculatorService
        Implements ICalculator

        Public Function Add(ByVal n1 As Double, ByVal n2 As Double) As Double Implements ICalculator.Add
            Dim result As Double = n1 + n2
            ' Code added to write output to the console window.
            Console.WriteLine("Received Add({0},{1})", n1, n2)
            Console.WriteLine("Return: {0}", result)
            Return result
        End Function

        Public Function Subtract(ByVal n1 As Double, ByVal n2 As Double) As Double Implements ICalculator.Subtract
            Dim result As Double = n1 - n2
            Console.WriteLine("Received Subtract({0},{1})", n1, n2)
            Console.WriteLine("Return: {0}", result)
            Return result

        End Function

        Public Function Multiply(ByVal n1 As Double, ByVal n2 As Double) As Double Implements ICalculator.Multiply
            Dim result As Double = n1 * n2
            Console.WriteLine("Received Multiply({0},{1})", n1, n2)
            Console.WriteLine("Return: {0}", result)
            Return result

        End Function


        Public Function Divide(ByVal n1 As Double, ByVal n2 As Double) As Double Implements ICalculator.Divide
            Dim result As Double = n1 / n2
            Console.WriteLine("Received Divide({0},{1})", n1, n2)
            Console.WriteLine("Return: {0}", result)
            Return result

        End Function
    End Class
End Namespace

Now the service contract is created and implemented. Build the solution to ensure there are no compilation errors and then proceed to How to: Host and Run a Basic Windows Communication Foundation Service to run the service. For troubleshooting information, see Troubleshooting the Getting Started Tutorial.

If you are using Visual Studio, on the Build menu click Build Solution (or press CTRL+SHIFT+B).

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