Monday, February 14, 2011

Getting Started with WCF (Windows Communication Foundation)


Windows Communication Foundation (Code named Indigo) is a programming platform and runtime system for building, configuring and deploying network-distributed services. It is the latest service oriented technology; Interoperability is the fundamental characteristics of WCF. It is unified programming model provided in .Net Framework 3.0. WCF is a combined feature of Web Service, Remoting, MSMQ and COM+. WCF provides a common platform for all .NET communication.

Advantages

  1. WCF is interoperable with other services when compared to .Net Remoting, where the client and service have to be .Net.
  2. WCF services provide better reliability and security in compared to ASMX web services.
  3. In WCF, there is no need to make much change in code for implementing the security model and changing the binding. Small changes in the configuration will make your requirements.
  4. WCF has integrated logging mechanism, changing the configuration file settings will provide this functionality. In other technology developer has to write the code.

Difference between WCF and Web service

Web service is a part of WCF. WCF offers much more flexibility and portability to develop a service when comparing to web service. Still we are having more advantages over Web service, following table provides detailed difference between them.
Features
Web Service
WCF
Hosting
It can be hosted in IIS
It can be hosted in IIS, windows activation service, Self-hosting, Windows service
Programming
[WebService] attribute has to be added to the class
[ServiceContraact] attribute has to be added to the class
Model
[WebMethod] attribute represents the method exposed to client
[OperationContract] attribute represents the method exposed to client
Operation
One-way, Request- Response are the different operations supported in web service
One-Way, Request-Response, Duplex are different type of operations supported in WCF
XML
System.Xml.serialization name space is used for serialization
System.Runtime.Serialization namespace is used for serialization
Encoding
XML 1.0, MTOM(Message Transmission Optimization Mechanism), DIME, Custom
XML 1.0, MTOM, Binary, Custom
Transports
Can be accessed through HTTP, TCP, Custom
Can be accessed through HTTP, TCP, Named pipes, MSMQ,P2P, Custom
Protocols
Security
Security, Reliable messaging, Transactions

A WCF Service is composed of three components parts viz,
1) Service Class - A WCF service class implements some service as a set of methods.
2) Host Environment - A Host environment can be a Console application or a Windows Service or a Windows Forms application or IIS as in case of the normal asmx web service in .NET.
3) Endpoints - All communications with the WCF service will happen via the endpoints. The endpoint is composed of 3 parts (collectively called as ABC's of endpoint) as defines below:
Address: The endpoints specify an Address that defines where the endpoint is hosted. It’s basically url.
Ex: http://localhost:8090/MyFirstWcfService/Service.svc
Contract: The endpoints specify a Contract that defines which methods of the Service class will be accessible via the endpoint; each endpoint may expose a different set of methods.
Different contracts in WCF

Service Contract

Service contracts describe the operation that service can provide. For Eg, a Service provide to know the temperature of the city based on the zip code, this service is called as Service contract. It will be created using Service and Operational Contract attribute.

Data Contract

Data contract describes the custom data type which is exposed to the client. This defines the data types, that are passed to and from service. Data types like int, string are identified by the client because it is already mention in XML schema definition language document, but custom created class or data types cannot be identified by the client e.g. Employee data type. By using DataContract we can make client to be aware of Employee data type that are returning or passing parameter to the method.

Message Contract

Default SOAP message format is provided by the WCF runtime for communication between Client and service. If it is not meeting your requirements then we can create our own message format. This can be achieved by using Message Contract attribute.

Fault Contract

Suppose the service I consumed is not working in the client application. I want to know the real cause of the problem. How I can know the error? For this we are having Fault Contract. Fault Contract provides documented view for error occurred in the service to client. This helps us to easy identity, what error has occurred.
Binding: The endpoints also define a binding that specifies how a client will communicate with the service and the address where the endpoint is hosted. Various components of the WCF are depicted in the figure below.
  • "A" stands for Address: Where is the service?
  • "B" stands for Binding: How can we talk to the service?
  • "C" stands for Contract: What can the service do for us?
Different bindings supported by WCF
Binding
Description
BasicHttpBinding
Basic Web service communication. No security by default
WSHttpBinding
Web services with WS-* support. Supports transactions
WSDualHttpBinding
Web services with duplex contract and transaction support
WSFederationHttpBinding
Web services with federated security. Supports transactions
MsmqIntegrationBinding
Communication directly with MSMQ applications. Supports transactions
NetMsmqBinding
Communication between WCF applications by using queuing. Supports transactions
NetNamedPipeBinding
Communication between WCF applications on same computer. Supports duplex contracts and transactions
NetPeerTcpBinding
Communication between computers across peer-to-peer services. Supports duplex contracts
NetTcpBinding
Communication between WCF applications across computers. Supports duplex contracts and transactions

Creating simple application using WCF

In this section we will create small application,

  • Open visual studio
  • Goto File -->Open New Website and give name as WCFApplication


Once you created application you will get default class files including Service.cs and IService.cs

IService is an interface it does contain Service contracts and Data Contracts and Service.cs is a normal class inherited by IService where you can all the methods and other stuff.
 
Copy and paste below code in to IService Interface 


 [ServiceContract]
public interface IService
{
      [OperationContract]
      string Welcome(string name);
}


Copy and paste below code in to Service class


    public class Service : IService
    {
        public string Welcome(string name)
        {
            return "Welcome to WCF World " + Name;
        }
    }

In web.config file


In this sample I have used basicHttpBinding

<system.serviceModel>
            <services>
   <service behaviorConfiguration="ServiceBehavior" name="Service">
    <endpoint address="http://localhost:1512/WcfApplication/Service.svc"
     binding="basicHttpBinding" bindingConfiguration="" contract="IService">
     <identity>
      <dns value="localhost" />
     </identity>
    </endpoint>
    <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" />
   </service>
  </services>
    <behaviors>
   <serviceBehaviors>
<behavior name="ServiceBehavior">                          
<serviceMetadata httpGetEnabled="true"/>   
<serviceDebug includeExceptionDetailInFaults="false"/>
</behavior>
 </serviceBehaviors>
</behaviors>
</system.serviceModel>
Finally we have successfully created a wcf service using basicHttpBinding


Calling Wcf Service using Console Application


Now we can call the Wcf service,for calling WCF service we have so many ways like uisng console app,windows app and web app,but here iam going for console application
Craete new console app from visual studio select project type as console application give some name as you like.


For calling WCF Service we have two methods one is Adding service reference to your console project and another one is creating proxy calss for Wcf Service and adding proxy class to your console project.


Here Iam going for adding service reference to my console app.for adding service reference right click on Solution explorer and click on AddServiceReference 





Copy and paste below code 

static void Main(string[] args)
        {
            //crete Object for Proxy class
            WcfServiceCall.ServiceClient objService = new WcfServiceCall.ServiceClient();
            Console.WriteLine("Please enter your Name ");
            string Message = objService.Welcome(Console.ReadLine());
            Console.WriteLine(Message);
            Console.ReadLine();
        }


In web.cofig file 

<endpoint address="http://localhost:1512/WcfApplication/Service.svc"
                binding="basicHttpBinding" bindingConfiguration="BasicHttpBinding_IService"
                contract="WcfServiceCall.IService" name="BasicHttpBinding_IService" />


after configuring web.config file click on run
So finally we have successfully created Wcf Service and we have call the service using Console application.

Windows Communication Foundation 4 Step by Step (Step By Step (Microsoft))
















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