Introduction of Window Communication Foundation

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About This

I am writing this article to explain the fundamentals of WCF application. Here I have explained basic template provided by the VS 2010 IDE.

What is WCF?

Windows Communication Foundation (WCF) is a framework for building service-oriented applications (SOA). As its name suggests, WCF provides the .NET Framework with a basis for writing code to communicate across components, applications, and systems. It formerly named as “Indigo”.

Why WCF?

WCF was designed according to the tenets of service orientation. A service is a piece of code you interact with through messages. Services are passive. They wait for incoming messages before doing any work. Clients are the initiators. Clients send messages to services to request work. Using WCF, we can send data as asynchronous messages from one application to other applications using below .NET Framework technologies.

How to Create WCF?

We will see how to create basic WCF applications using Visual Studio IDE. Before going into the application, see some of the basic terms used in the application.

Step 1

Create a new WCF project using VS IDE.

Step 2

Delete the existing .cs files (IService.cs & Service.cs) and Create new two files IPersonService & PersonService.

IPersonService.cs has the following method declarations:

Person CreatePerson(Person createPerson); //Method will create a new person
List <Person> GetAllPerson(); 	     //Method will display all the persons in the list
Person GetAPerson(string id); 	     //Method will display a person
Person UpdatePerson(string id, Person updatePerson); //Method will update a person
void DeletePerson(string id); 	     //Method will delete a person

These codes are similar to that of normal Web Services, in the WCF application IPersonService interface class and methods are decorated with [ServiceContract] and [OperationContract] using System.ServiceModel namespace.

[ServiceContract] - A service contract specifies what an endpoint communicates to the outside world, i.e., only the class decorated with [ServiceContract] is visible for WCF client application.

[OperationContract] - Indicates that a method defines an operation that is part of a service contract in an application, i.e., only the method decorated with [OperationContract] is visible for WCF client application and class of this method must be decorated with [ServiceContract].

Sample template code created by the IDE is:

[ServiceContract]
public interface IPersonService
{
    [OperationContract]
    Person CreatePerson(Person createPerson);
    [OperationContract]
    List<Person> GetAllPerson();
    [OperationContract]
    Person GetAPerson(string id);
    [OperationContract]
    Person UpdatePerson(string id, Person updatePerson);
    [OperationContract]
    void DeletePerson(string id);
}

We can write class and its method as like Web Services, but we have to decorate with class & method using [ServiceContract] & [OperationContract]

How to Test WCF?

Step 1

You can run the application; it will run the “WCF Service Host” and run the WCF Test Client application.

Or you can run & test the application using template created by the IDE. To test the WCF application, you have to run WCFTestClient.exe which is in C:\Program Files\Microsoft Visual Studio 10.0\Common7\IDE with the application URL (like http://localhost/demo/mex).

WCFTestClient.exe http://localhost/demo/mex

Step 2

Testing method CreatePerson()

• Double click the “CreatePerson()” method in the WCT Test Client window
• Enter the values in the “Request” section
• Click “Invoke” button.
• Answer will populate in the “Responses” Section

Similarly, you can Invoke the methods GetAllPersion(), GetAPerson(), UpdatePerson() & DeletePerson().

What is Endpoints in WCF?

An address associated with WCF service which is used to locate and identify the WCF service is known as endpoint.

Client applications (like Remoting, WSE, ASMX, MSMQ, and Enterprise Services) can communicate with WCF Services using these Endpoints.

Endpoint Address - All communication with a Windows Communication Foundation (WCF) service occurs through its endpoints. Each “ServiceEndpoint“ contains an Address, a Binding, and a Contract. It usually known as ABC.

• Address – Specifies where to find the service
• Binding – Specifies how to communicate with the service
• Contact – Specifies which operations are available

Creating Service Endpoint

Step 1

In the application Solution Explorer, right click the App.config file in the popup menu click “Edit WCF Configuration” item.

It pops up the WCF Configuration window.

There are three Endpoints in the configuration file, by save & close, these changes will reflect in the app.config file.

App.Cofig file has three Endpoints:

1. Mex
   • Address=”mex”
   • Binding=”mexHttpBinding”
   • Contract=”IMetadataExchange”
2. Basic
   • Address=”basic”
   • Binding=”basicHttpBinding”
   • Contract=”WCFPersonService.IPersonService”
3. WS
   • Address=”ws”
   • Binding=”wsHttpBinding”
   • Contract=”WCFPersonService.IPersonService”

In these Endpoints, Mex endpoint is mandatory; it must have all the WCF application. Mex is exposing the Metadata to the client application.

Client can communicate using any of other two endpoints (Basic, WS).

How to Consume the WCF Service?

Add the WCF Service reference using Add Reference... menu in the console application, see the below code to consume the WCF services.

ServiceReference1.Service1Client sc= new ServiceReference1.Service1Client("basic");
Person varPerson = sc.CreatePerson(objPerson); // This line creates a person using
		// WCF application & returns that person to the client application

Please refer to the attached project for detailed code.

Conclusion

I hope this article helps you to understand the basics of WCF applications. Please feel free to comment.

References

1. http://msdn.microsoft.com/en-us/library/dd560536.aspx
2. http://msdn.microsoft.com/en-us/magazine/cc163647.aspx
3. http://msdn.microsoft.com/en-us/library/ee958158.aspx

History

• 2^nd September, 2011: Initial version