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Understand WCF: Part 7: Self Hosting in WCF Application

You are reading the "Understand WCF" article series. In this series we are explaining all about WCF. The previous few articles explained various important concepts of WCF applications. You can read them here:
In this article we will learn to host WCF applications in a self-hosting environment. As we know, WCF is the next and updated solution of Web Services and one basic difference between them is, it's a hosting environment. We can host a Web Service only in an IIS server and consume it by HTTP protocol. WCF leverages the limitation, we can host a WCF service in various environments. So, let's see what are the possible ways to host a WCF service.
 

Various WCF hosting environments

 
The following are the various hosting environments:
  • Self-hosting
  • IIS server
  • Windows Activation Server (WAS)
Ok, so there are three different environments for WCF services. But the most popular environment is IIS server and the next choice is to self-hosting. We can say that 70% of services run in IIS server, 25% runs self-hosted and the remaining are hosted in WAS.
 

What WCF Self-Hosting is

 
Let's learn the concept of Self-Hosting. The single line answer is "It hosts with the same solution". What does that mean? It means that, we have our project (it may be Windows or a web application or something else) and we want to host one WCF service within this solution locally. This type of hosting is called Self-Hosting. To implement self hosting we need to include System.Service.Model.ServiceHost namespace that we will see in the example.
 
Let's implement a self-hosting example step-by-step.
 
We will now implement the self-hosting example step-by-step. Please follow it.
 
Step 1: Create a console application.
 
As we said, self-hosting can be done in any type of application; we will implement self-hosting in the console application.
 
wcf Console application 
 
We have given the name "client" to this console application. Now proceed to the next step.
 
Step 2: Add the System.ServiceModel.dll to the project.
 
This is our next step, go to Solution Explorer and right-click on References then select "Add references" then add a reference for "System.ServiceModel".
 
wcf System.ServiceModel reference 
 
Once you click on "OK" the reference will be added to your solution. So, click "OK" and go to the next step.
 
Step 3: Add one interface to the solution.
 
As we know in WCF we need to implement a ServiceContract, so we need to define the interface. Add one interface to the solution.
 
wcf Interface 
 
Step 4: Add the following code to the interface.
 
Now we will declare the methods in the interface. Here is simple code.
  1. using System;  
  2. using System.Collections.Generic;  
  3. using System.Linq;  
  4. using System.ServiceModel;  
  5. using System.Text;  
  6. using System.Threading.Tasks;   
  7.   
  8. namespace Client  
  9. {  
  10.     [ServiceContract]  
  11.     interface ITestService  
  12.     {  
  13.         [OperationContract]  
  14.         String WelcomeUser(String name);  
  15.     }  
  16. }  
So, we have declared the interface called "ITestService". This interface contains one method (WelcomeUser) that we will implement within the Service class in the next step.
 
Step 5: Add one class into the solution.
 
Since we need to implement the interface above, we will include one class file and we will get it done. So, add a class file to the solution.
 
wcf class 
 
Add the following code to our class:
  1. using System;  
  2. using System.Collections.Generic;  
  3. using System.Linq;  
  4. using System.Text;  
  5. using System.Threading.Tasks;  
  6.    
  7. namespace Client  
  8. {  
  9.     public class TestService : ITestService  
  10.     {  
  11.             public String WelcomeUser(String name)  
  12.             {  
  13.                 return String.Format("Welcome " +  name);  
  14.             }  
  15.     }  
  16. }  
Just look at that, we have implemented the "ITestService" interface within the "TestService" class. We have defined the "WelcomeUser()" method into it.
 
Step 6: Open the Main() function of the application and modify the code.
 
Our service is now set up and we need to host the service. To host the service we need to open the Program class (the default in a console app) and modify the code like below.
  1. using System;  
  2. using System.Collections.Generic;  
  3. using System.Linq;  
  4. using System.Text;  
  5. using System.Diagnostics;  
  6. using System.Collections;  
  7. using Client;  
  8. using System.ServiceModel;  
  9. using System.ServiceModel.Description;   
  10. namespace Client  
  11. {  
  12.     class Program  
  13.     {  
  14.         static void Main(string[] args)  
  15.         {              
  16.             Uri baseAddress = new Uri("http://localhost:6525/TestService");   
  17.             using (ServiceHost host = new ServiceHost(typeof(Client.TestService), baseAddress))  
  18.             {  
  19.                 ServiceMetadataBehavior smb = new ServiceMetadataBehavior();  
  20.                 smb.HttpGetEnabled = true;  
  21.                 smb.MetadataExporter.PolicyVersion = PolicyVersion.Policy15;  
  22.                 host.Description.Behaviors.Add(smb);   
  23.                 host.Open();   
  24.                 Console.WriteLine("The service is ready at: {0}", baseAddress);  
  25.                 Console.WriteLine("Press <Enter> to stop the service");  
  26.                 Console.ReadKey();  
  27.                 host.Close();  
  28.                 Console.ReadLine();  
  29.             }  
  30.         }  
  31.     }  
  32. }  
Ok, we have written code to host the service in the "http://localhost:6525/TestService" URL.
 
Step 7: Run the application.
 
This is the last step to host the service. Press F5 now and run the application. Here is the output. We see that the service is hosted in the same URL.
 
Self Hosting in WCF 
 
Note: If you get the error "Assembly cannot read blab bla" then please run the Visual Studio in Administrator mode (I have spent much time solving the issue).
 
Conclusion
 
In this step-by-step article, we have learned to host a WCF service in a Self-Hosting environment. Hope you have learned it. In a future article, we will dig more into this subject (WCF).
 


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