WCF Beginners : ABC of EndPoint and Channel

What does ABC imply for WCF Service ? => ENDPOINT

What does ABC imply for WCF Service ? => ENDPOINT

Configuration of endpoint is done as below :

Contract: Attribute used in WCF is Service Contract

E.g.:

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using System;

using System.ServiceModel;

namespace Microsoft.ServiceModel.Samples

{

    // Define a service contract.

    [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);

    }

    // Step 1: Create service class that implements the service contract.

    public class CalculatorService : ICalculator

    {

         // Step 2: Implement functionality for the service operations.

        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;

        }

    }

}

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Where and How?

Following is configuration required for WCF service, Configuration we will see in depth in later articles,

Note following tabgs,

Services

->Service[attribute->Name]

->Enpoint[Attribute-> address, binding, contract]

Configuration is enough for understanding the explanation and figure mentioned earlier.

xml version="1.0" encoding="utf-8" ?>

<configuration>

  <system.serviceModel>

    <behaviors>

      <serviceBehaviors>

        <behavior name="CalculatorServiceBehavior">

          <serviceMetadata httpGetEnabled="True"/>

        behavior>

      serviceBehaviors>

    behaviors>

    <services>

      <service name="Microsoft.ServiceModel.Samples.CalculatorService"

               behaviorConfiguration="CalculatorServiceBehavior">

        <endpoint address="http://localhost:8080/calcservice" binding="basicHttpBinding" contract="ICalculator"/>

        <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange"/>

      service>

    services>

  system.serviceModel>

configuration>

EndPoints:

All communication with a Windows Communication Foundation (WCF) service occurs through the endpoints of the service. Endpoints provide clients access to the functionality offered by a WCF service.

Each endpoint consists of four properties:

·         An address that indicates where the endpoint can be found. 

·         A binding that specifies how a client can communicate with the endpoint. 

·         A contract that identifies the operations available. 

·         A set of behaviors (OperationContract) that specify local implementation details of the endpoint. 

Client Communication:

• ·         Consume Services via Channels based on Endpoints (Binding)
• ·         Client retrieves Endpoint using Metadata information (WSDL)
• ·         Regarding WSDL and Metadata we will see in coming articles.

Channels is whole huge topic can’t be covered in scope of this article though.

Channels Abstract:

The Windows Communication Foundation (WCF) channel stack is a layered communication stack with one or more channels that process messages. WCF binding is composed of binding elements and each binding element is corresponding to a specific channel in Channel Stack.

Application-to-application communication can have many aspects. Perhaps a SOAP envelope needs to be created, for example, wrapping whatever information is being sent. Maybe one or more of the WS-* technologies should be used, such as WS-ReliableMessaging or WS-Security. Perhaps the information to be sent should be represented using JavaScript Object Notation (JSON). Or maybe none of these things are required: Just sending plain XML might be sufficient. And however a message is structured, it must eventually be sent to its destination using HTTP, TCP, Microsoft Messaging Queuing (MSMQ), or something else.

 WCF's Design for Diversity was the reason for which 2 big ideas were introduced “Binding and Channels” to WCF. By specifying a particular binding, a WCF client or service implicitly creates a channel stack that implements a particular set of communication behaviors. So, a single channel in channel stack is unit of binding.

Next we will see ,

• ServiceContract
• OperatioCOntract
• DataContract
• MessageContract