WCF Interview Questions and Answers

1. What is WCF?
WCF stands for Windows Communication Foundation. It is a Software development kit for developing services on Windows. WCF is introduced in .NET 3.0. in the System.ServiceModel namespace. WCF is based on basic concepts of Service oriented architecture (SOA)

2. What is endpoint in WCF service?
The endpoint is an Interface which defines how a client will communicate with the service. It consists of three main points: Address,Binding and Contract.

3. Explain Address,Binding and contract for a WCF Service?
Address:Address defines where the service resides.
Binding:Binding defines how to communicate with the service.
Contract:Contract defines what is done by the service.

4. What are the various address format in WCF?
a)HTTP Address Format:--> http://localhost:
b)TCP Address Format:--> net.tcp://localhost:
c)MSMQ Address Format:--> net.msmq://localhost:

5. What are the types of binding available in WCF?
A binding is identified by the transport it supports and the encoding it uses. Transport may be HTTP,TCP etc and encoding may be text,binary etc. The popular types of binding may be as below:
a)BasicHttpBinding
b)NetTcpBinding
c)WSHttpBinding
d)NetMsmqBinding

6. What are the types of contract available in WCF?
The main contracts are:
a)Service Contract:Describes what operations the client can perform.
b)Operation Contract : defines the method inside Interface of Service.
c)Data Contract:Defines what data types are passed
d)Message Contract:Defines wheather a service can interact directly with messages

7. What are the various ways of hosting a WCF Service?
a)IIS b)Self Hosting c)WAS (Windows Activation Service)

8. What is the proxy for WCF Service?
A proxy is a class by which a service client can Interact with the service.
By the use of proxy in the client application we are able to call the different methods exposed by the service


9. How can we create Proxy for the WCF Service?
We can create proxy using the tool svcutil.exe after creating the service.
We can use the following command at command line.
svcutil.exe *.wsdl *.xsd /language:C# /out:SampleProxy.cs /config:app.config

10.What is the difference between WCF Service and Web Service?
a)WCF Service supports both http and tcp protocol while webservice supports only http protocol.
b)WCF Service is more flexible than web service.

11.What is DataContract and ServiceContract?Explain 
Data represented by creating DataContract which expose the
data which will be transefered /consumend from the serive
to its clients.

**Operations which is the functions provided by this
service.

To write an operation on WCF,you have to write it as an
interface,This interface contains the "Signature" of the
methods tagged by ServiceContract attribute,and all methods
signature will be impelemtned on this interface tagged with
OperationContract attribute.

and to implement these serivce contract you have to create
a class which implement the interface and the actual
implementation will be on that class.


Code Below show How to create a Service Contract:

Code:

[ServiceContract]
Public Interface IEmpOperations
{
[OperationContract]
Decimal Get EmpSal(int EmpId);

}

Class MyEmp: IEmpOperations
{
Decimal Get EmpSal()
{
// Implementation of this method.
}
}