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How to: Implement a Discoverable Service that Registers with the Discovery Proxy

This topic is the second of four topics that discusses how to implement a discovery proxy. In the previous topic, How to: Implement a Discovery Proxy, you implemented a discovery proxy. In this topic, you create a WCF service that sends announcement messages (Hello and Bye) to the discovery proxy, causing it to register and unregister itself with the discovery proxy.

To define the service contract

  1. Add a new console application project to the DiscoveryProxyExample solution called Service.

  2. Add references to the following assemblies:

    1. System.ServiceModel

    2. System.ServiceModel.Discovery

  3. Add a new class to the project called CalculatorService.

  4. Add the following using statements.

    using System;
using System.ServiceModel;

  5. Within CalculatorService.cs, define the service contract.

    // Define a service contract.
    [ServiceContract(Namespace = "http://Microsoft.Samples.Discovery")]
    public interface ICalculatorService
    {
        [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);
    }

  6. Also within CalculatorService.cs, implement the service contract.

    // Service class which implements the service contract.    
    public class CalculatorService : ICalculatorService
    {
        public double Add(double n1, double n2)
        {
            double result = n1 + n2;
            Console.WriteLine("Received Add({0},{1})", n1, n2);
            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;
        }
    }

To host the service

  1. Open the Program.cs file that was generated when you created the project.

  2. Add the following using statements.

    using System;
using System.ServiceModel;
using System.ServiceModel.Description;
using System.ServiceModel.Discovery;

  3. Within the Main() method, add the following code:

    // Define the base address of the service
Uri baseAddress = new Uri("net.tcp://localhost:9002/CalculatorService/" + Guid.NewGuid().ToString());
// Define the endpoint address where announcement messages will be sent
Uri announcementEndpointAddress = new Uri("net.tcp://localhost:9021/Announcement");

// Create the service host
ServiceHost serviceHost = new ServiceHost(typeof(CalculatorService), baseAddress);
try
{
   // Add a service endpoint
   ServiceEndpoint netTcpEndpoint = serviceHost.AddServiceEndpoint(typeof(ICalculatorService), new NetTcpBinding(), string.Empty);              

   // Create an announcement endpoint, which points to the Announcement Endpoint hosted by the proxy service.
   AnnouncementEndpoint announcementEndpoint = new AnnouncementEndpoint(new NetTcpBinding(), new EndpointAddress(announcementEndpointAddress));

   // Create a ServiceDiscoveryBehavior and add the announcement endpoint
   ServiceDiscoveryBehavior serviceDiscoveryBehavior = new ServiceDiscoveryBehavior();
                serviceDiscoveryBehavior.AnnouncementEndpoints.Add(announcementEndpoint);

   // Add the ServiceDiscoveryBehavior to the service host to make the service discoverable
   serviceHost.Description.Behaviors.Add(serviceDiscoveryBehavior);

   // Start listening for messages
  serviceHost.Open();

   Console.WriteLine("Calculator Service started at {0}", baseAddress);
   Console.WriteLine();
   Console.WriteLine("Press <ENTER> to terminate the service.");
   Console.WriteLine();
   Console.ReadLine();

   serviceHost.Close();
}
catch (CommunicationException e)
{
   Console.WriteLine(e.Message);
}
catch (TimeoutException e)
{
   Console.WriteLine(e.Message);
}   

if (serviceHost.State != CommunicationState.Closed)
{
   Console.WriteLine("Aborting the service...");
   serviceHost.Abort();
}

You have completed implementing a discoverable service. Continue on to How to: Implement a Client Application that Uses the Discovery Proxy to Find a Service.

Example

This is the full listing of the code used in this topic.

    // CalculatorService.cs
    //----------------------------------------------------------------
    // Copyright (c) Microsoft Corporation.  All rights reserved.
    //----------------------------------------------------------------
    
    using System;
    using System.ServiceModel;
    
    namespace Microsoft.Samples.Discovery
    {
        // Define a service contract.
        [ServiceContract(Namespace = "http://Microsoft.Samples.Discovery")]
        public interface ICalculatorService
        {
            [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);
        }
    
        // Service class which implements the service contract.    
        public class CalculatorService : ICalculatorService
        {
            public double Add(double n1, double n2)
            {
                double result = n1 + n2;
                Console.WriteLine("Received Add({0},{1})", n1, n2);
                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;
            }
        }
    }

    // Program.cs
    //----------------------------------------------------------------
    // Copyright (c) Microsoft Corporation.  All rights reserved.
    //----------------------------------------------------------------
    
    using System;
    using System.ServiceModel;
    using System.ServiceModel.Description;
    using System.ServiceModel.Discovery;
    
    namespace Microsoft.Samples.Discovery
    {
        class Program
        {
            public static void Main()
            {
                Uri baseAddress = new Uri("net.tcp://localhost:9002/CalculatorService/" + Guid.NewGuid().ToString());
                Uri announcementEndpointAddress = new Uri("net.tcp://localhost:9021/Announcement");
    
                ServiceHost serviceHost = new ServiceHost(typeof(CalculatorService), baseAddress);
                try
                {
                    ServiceEndpoint netTcpEndpoint = serviceHost.AddServiceEndpoint(typeof(ICalculatorService), new NetTcpBinding(), string.Empty);              
    
                    // Create an announcement endpoint, which points to the Announcement Endpoint hosted by the proxy service.
                    AnnouncementEndpoint announcementEndpoint = new AnnouncementEndpoint(new NetTcpBinding(), new EndpointAddress(announcementEndpointAddress));
                    ServiceDiscoveryBehavior serviceDiscoveryBehavior = new ServiceDiscoveryBehavior();
                    serviceDiscoveryBehavior.AnnouncementEndpoints.Add(announcementEndpoint);
    
                    // Make the service discoverable
                    serviceHost.Description.Behaviors.Add(serviceDiscoveryBehavior);
    
                    serviceHost.Open();
    
                    Console.WriteLine("Calculator Service started at {0}", baseAddress);
                    Console.WriteLine();
                    Console.WriteLine("Press <ENTER> to terminate the service.");
                    Console.WriteLine();
                    Console.ReadLine();
    
                    serviceHost.Close();
                }
                catch (CommunicationException e)
                {
                    Console.WriteLine(e.Message);
                }
                catch (TimeoutException e)
                {
                    Console.WriteLine(e.Message);
                }   
                
                if (serviceHost.State != CommunicationState.Closed)
                {
                    Console.WriteLine("Aborting the service...");
                    serviceHost.Abort();
                }
            }
        }
    }

See Also

Tasks

How to: Implement a Discovery Proxy
How to: Implement a Client Application that Uses the Discovery Proxy to Find a Service

Other Resources

WCF Discovery

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