WCF - Creating and Implementing a Service in C#

Category: .NET Framework

WCF - Creating a Service and Client in ASP.NET 3.5 and C#

Introduction

The Windows Communication Foundation (WCF) is great for allowing applications to interact and integrate with one another across platforms. WCF is a powerful introduction to the .NET Framework, aimed at filling gaps left by such implementations as Web Services, and this article will guide you through creating a simple WCF Service, and then implementing that Service with a Client. We can host the Service on the same machine as the Client, which is great for testing. This article will result in us creating a simple calculator service, that we can consume in a client. The Client will call the service to use the simple calculator tasks of addition, subtract, multiply and divide.

What we will learn in this article:

  • How to Create a WCF Service in Visual Studio.NET 2008;
  • How to consume the WCF Service in a Client Console application.

Please Note:
To create this example WCF Service, we will be using Visual Studio.NET 2008 with ASP.NET 3.5, which comes with WCF built-in. However, this article will make use of the CMD Shell from the Windows SDK to build the client application, which can be downloaded from Microsoft here

Getting Started with our WCF Service
To begin, we will start up Visual Studio and create a New Project, Console Application. We will start with our WCF Service. Name it Service1, and choose a location. When the project opens, we should see something like this:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ProgrammingHelp.WCFService1
{
class Program
{
static void Main(string[] args)
{
}
}
}

Our next step is to add a reference to the ServiceModel.dll. To do this, right-click on the References folder in Solution Explorer, and choose Add Reference. In the ASP.NET Tab, scroll down to System.ServiceModel, select it and click Ok. Now add a using directive:

using System.ServiceModel;

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Now we can create our interface for the calculator, which includes our Operation Contracts. The contract defines the functionality offered by the Service, and describes how to use it. Add the following to the namespace:

[ServiceContract(Namespace = "http://ProgrammingHelp.Service/")]
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);
}

Now to implement this contract, we create the methods in a class which inherits our interface:

class CalculatorService : ICalculator
{
public Double Add(Double num1, Double num2)
{
Double answer = num1 + num2;
Console.WriteLine("Call made: Add({0},{1})", num1, num2);
Console.WriteLine("Answer: {0}", answer);
return answer;
}

public Double Subtract(Double num1, Double num2)
{
Double answer = num1 - num2;
Console.WriteLine("Call made: Subtract({0},{1})", num1, num2);
Console.WriteLine("Answer: {0}", answer);
return answer;
}

public Double Multiply(Double num1, Double num2)
{
Double answer = num1 * num2;
Console.WriteLine("Call made: Multiply({0},{1})", num1, num2);
Console.WriteLine("Answer: {0}", answer);
return answer;
}

public Double Divide(Double num1, Double num2)
{
Double answer = num1 / num2;
Console.WriteLine("Call made: Divide({0},{1})", num1, num2);
Console.WriteLine("Answer: {0}", answer);
return answer;
}
}

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Now we will create the Main object inside the Program class. This will add the Service EndPoint and ultimately initialize our Service. Here, we will use the ServiceMetadataBehavior class, which is in the System.ServiceModel.Description namespace. We will need to also add a reference to this.

class Program
{
static void Main(string[] args)
{
Uri baseAddr = new Uri("http://localhost:8000/WCFService1");
ServiceHost localHost = new ServiceHost(typeof(CalculatorService), baseAddr);

try
{
localHost.AddServiceEndpoint(typeof(ICalculator), new WSHttpBinding(), "CalculatorService");

ServiceMetadataBehavior smb = new ServiceMetadataBehavior();
smb.HttpGetEnabled = true;
localHost.Description.Behaviors.Add(smb);

localHost.Open();
Console.WriteLine("Service initialized.");
Console.WriteLine("Press the ENTER key to terminate service.");
Console.WriteLine();
Console.ReadLine();

localHost.Close();
}
catch (CommunicationException ex)
{
Console.WriteLine("Oops! Exception: {0}", ex.Message);
localHost.Abort();
}
}
}

Now our service is pretty much complete and ready to be consumed. Our Entire Service code looks like this:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

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

namespace ProgrammingHelp.WCFService1
{
[ServiceContract(Namespace = "http://ProgrammingHelp.Service/")]
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);
}

class CalculatorService : ICalculator
{
public Double Add(Double num1, Double num2)
{
Double answer = num1 + num2;
Console.WriteLine("Call made: Add({0},{1})", num1, num2);
Console.WriteLine("Answer: {0}", answer);
return answer;
}

public Double Subtract(Double num1, Double num2)
{
Double answer = num1 - num2;
Console.WriteLine("Call made: Subtract({0},{1})", num1, num2);
Console.WriteLine("Answer: {0}", answer);
return answer;
}

public Double Multiply(Double num1, Double num2)
{
Double answer = num1 * num2;
Console.WriteLine("Call made: Multiply({0},{1})", num1, num2);
Console.WriteLine("Answer: {0}", answer);
return answer;
}

public Double Divide(Double num1, Double num2)
{
Double answer = num1 / num2;
Console.WriteLine("Call made: Divide({0},{1})", num1, num2);
Console.WriteLine("Answer: {0}", answer);
return answer;
}
}

class Program
{
static void Main(string[] args)
{
Uri baseAddr = new Uri("http://localhost:8000/WCFService1");
ServiceHost localHost = new ServiceHost(typeof(CalculatorService), baseAddr);

try
{
localHost.AddServiceEndpoint(typeof(ICalculator), new WSHttpBinding(), "CalculatorService");

ServiceMetadataBehavior smb = new ServiceMetadataBehavior();
smb.HttpGetEnabled = true;
localHost.Description.Behaviors.Add(smb);

localHost.Open();
Console.WriteLine("Service initialized.");
Console.WriteLine("Press the ENTER key to terminate service.");
Console.ReadLine();

localHost.Close();
}
catch (CommunicationException ex)
{
Console.WriteLine("Oops! Exception: {0}", ex.Message);
localHost.Abort();
}
}
}
}

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We will create our Client in a new Project, but within the same Solution as the Service. To do this, right-click the Solution in Solution Explorer, and choose Add > New Project.. Console Application. Name it ClientApp. As with the Service, add a reference to the System.ServiceModel.dll and a using directive.
Next, run the service from Visual Studio (hit F5), and then we need to goto the Start Menu > All Programs > Microsoft Windows SDK > CMD Shell. If you do not have this, then you will need to download the Windows SDK at the link at the top of this article.
You should have something like this:


[Click to see full-size]

Now we want to navigate to our ClientApp folder using cd (Change Directory). Example, input cd "C:\Users\xxxxxx\Visual Studio 2008\Documents\Consoles\WCFService1\ClientApp" and hit Enter:


[Click to see full-size]

Finally, enter the following to generate the necessary files for our Client and then hit Enter:
svcutil.exe /language:cs /out:generatedProxy.cs /config:app.config http://localhost:8000/WCFService1
This will generate our Client files.


[Click to see full-size]

You can now close the CMD Shell window. Navigate to your ClientApp folder and verify that the files were created in the correct location. You should now have app.config and generatedProxy.cs.
We can now also terminate the Service and go back into Visual Studio. In Solution Explorer, right-click the ClientApp project and choose to Add > Existing Item. Enter * in the File name box and hit enter. There, choose to add the generatedProxy.cs and the app.config we just created. The App.config file should look something like this:


openTimeout="00:01:00" receiveTimeout="00:10:00" sendTimeout="00:01:00"
bypassProxyOnLocal="false" transactionFlow="false" hostNameComparisonMode="StrongWildcard"
maxBufferPoolSize="524288" maxReceivedMessageSize="65536"
messageEncoding="Text" textEncoding="utf-8" useDefaultWebProxy="true"
allowCookies="false">
maxBytesPerRead="4096" maxNameTableCharCount="16384" />
enabled="false" />
realm="" />
algorithmSuite="Default" establishSecurityContext="true" />

binding="wsHttpBinding" bindingConfiguration="WSHttpBinding_ICalculator"
contract="ICalculator" name="WSHttpBinding_ICalculator">

 

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Notice the EndPoint was generated for our Client.
The generatedProxy.cs includes our interface and all of our methods:

//------------------------------------------------------------------------------
//
// This code was generated by a tool.
// Runtime Version:2.0.50727.3074
//
// Changes to this file may cause incorrect behavior and will be lost if
// the code is regenerated.
//
//------------------------------------------------------------------------------


[System.CodeDom.Compiler.GeneratedCodeAttribute("System.ServiceModel", "3.0.0.0")]
[System.ServiceModel.ServiceContractAttribute(Namespace="http://ProgrammingHelp.Service/", ConfigurationName="ICalculator")]
public interface ICalculator
{
[System.ServiceModel.OperationContractAttribute(Action="http://ProgrammingHelp.Service/ICalculator/Add", ReplyAction="http://ProgrammingHelp.Service/ICalculator/AddResponse")]
double Add(double n1, double n2);

[System.ServiceModel.OperationContractAttribute(Action="http://ProgrammingHelp.Service/ICalculator/Subtract", ReplyAction="http://ProgrammingHelp.Service/ICalculator/SubtractResponse")]
double Subtract(double n1, double n2);

[System.ServiceModel.OperationContractAttribute(Action="http://ProgrammingHelp.Service/ICalculator/Multiply", ReplyAction="http://ProgrammingHelp.Service/ICalculator/MultiplyResponse")]
double Multiply(double n1, double n2);

[System.ServiceModel.OperationContractAttribute(Action="http://ProgrammingHelp.Service/ICalculator/Divide", ReplyAction="http://ProgrammingHelp.Service/ICalculator/DivideResponse")]
double Divide(double n1, double n2);
}

[System.CodeDom.Compiler.GeneratedCodeAttribute("System.ServiceModel", "3.0.0.0")]
public interface ICalculatorChannel : ICalculator, System.ServiceModel.IClientChannel
{
}

[System.Diagnostics.DebuggerStepThroughAttribute()]
[System.CodeDom.Compiler.GeneratedCodeAttribute("System.ServiceModel", "3.0.0.0")]
public partial class CalculatorClient : System.ServiceModel.ClientBase, ICalculator
{
public CalculatorClient()
{
}

public CalculatorClient(string endpointConfigurationName) :
base(endpointConfigurationName)
{
}

public CalculatorClient(string endpointConfigurationName, string remoteAddress) :
base(endpointConfigurationName, remoteAddress)
{
}

public CalculatorClient(string endpointConfigurationName, System.ServiceModel.EndpointAddress remoteAddress) :
base(endpointConfigurationName, remoteAddress)
{
}

public CalculatorClient(System.ServiceModel.Channels.Binding binding, System.ServiceModel.EndpointAddress remoteAddress) :
base(binding, remoteAddress)
{
}

public double Add(double n1, double n2)
{
return base.Channel.Add(n1, n2);
}

public double Subtract(double n1, double n2)
{
return base.Channel.Subtract(n1, n2);
}

public double Multiply(double n1, double n2)
{
return base.Channel.Multiply(n1, n2);
}

public double Divide(double n1, double n2)
{
return base.Channel.Divide(n1, n2);
}
}

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Finally, we can add the logic to our Client Program.cs, which will interact with the Service, using the methods. We call each method with parameters for the Service to calculate and then return the answers back to the Client:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using System.ServiceModel;

namespace ProgrammingHelp.ClientApp
{
class ClientApp
{
static void Main(string[] args)
{
CalculatorClient client = new CalculatorClient();

double value1 = 100.00D;
double value2 = 15.99D;
double result = client.Add(value1, value2);
Console.WriteLine("{0} + {1} = {2}", value1, value2, result);

value1 = 145.00D;
value2 = 76.54D;
result = client.Subtract(value1, value2);
Console.WriteLine("{0} - {1} = {2}", value1, value2, result);

value1 = 9.00D;
value2 = 81.25D;
result = client.Multiply(value1, value2);
Console.WriteLine("{0} x {1} = {2}", value1, value2, result);

value1 = 22.00D;
value2 = 7.00D;
result = client.Divide(value1, value2);
Console.WriteLine("{0} / {1} = {2}", value1, value2, result);

client.Close();

Console.WriteLine();
Console.WriteLine("Press the ENTER key to terminate client.");
Console.ReadLine();
}
}
}

To test the client, right-click on the Service project in Solution Explorer, and choose rebuild. Then do the same for the Client. Now we can goto the bin/debug/ folder of each project and first run the WCFService1.exe to initialize, and then the ClientApp.exe. We should have an output like this:


[Click to see full-size]


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