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What is WCF?

Windows Communication Foundation (WCF) is an SDK for developing and deploying services on Windows.and it (Code named Indigo) is a programming platform  and  runtime system for building, configuring and deploying network-distributed services.

WCF provides a runtime environment for your services, enabling you to expose CLR types as services, and to consume other services as CLR types. It is the latest service oriented technology; Interoperability is the fundamental characteristics of WCF.

Windows Communication Foundation (WCF) is unified programming model provided in .Net Framework 3.0. WCF is a combined features of Web Service, Remoting, MSMQ and COM+. WCF provides a common platform for all .NET communication.

Define endpoint in WCF service?

It consists of three main points: Address, Binding and Contract. The Client, how to communicate with the service is done by endpoint. 

Define difference between WCF and Web service ?

1. Web Service can be hosted in IIS but WCF can be hosted in IIS, windows activation service, Self-hosting, Windows service

2. [WebService] attribute has to be added to the class. In WCF [ServiceContraact] attribute has to be added to the class

3. In Web Srvices[WebMethod] attribute represents the method exposed to client,In WCF [OperationContract] attribute represents the method exposed to client

4. Web services One-way, Request- Response are the different operations supported in web service In WCF One-Way, Request-Response, Duplex are different type of operations supported in WCF

How many Types of Contracts in WCF?

There are four types of Contracts in WCF-
1. Service contracts
2. Data contracts
3. Fault contracts
4. Message contracts

What is Contract in WPF?

In WCF, all services expose contracts. The contract is a platform-neutral and standard way of describing what the service does. WCF defines four types of contracts.

Define Service contracts?

Define  which operations the client can perform on the service. Service contracts are the subject of the next chapter, but are used extensively in every chapter in this book.

Define Data contracts in WCF?

Define which data types are passed to and from the service. WCF defines implicit contracts for built-in types such as int and string, but you can easily define explicit opt-in data contracts for custom types

Define Fault contracts?

Define which errors are raised by the service, and how the service handles and propagates errors to its clients.

DEfine Message contracts in WCF?

Allow the service to interact directly with messages. Message contracts can be typed or untyped, and are useful in interoperability cases and when there is an existing message format you have to comply with.

Define the various ways of hosting a WCF Service?

2)Self Hosting
3)WAS (Windows Activation Service)

What are the main components of WCF?

The main components are 
1. Service class
2. Hosting environment
3. End point

What are the WCF transport schemas ?

3)Peer network
4)IPC (Inter-Process Communication over named pipes)

What is Throttling in WCF?

Throttling enables  we  to restrain client connections and the load they place on  our service. Throttling enables we  to ignore  maxing out our service and the underlying resources it allocates and uses. If the settings we configure are exceeded, WCF will automatically place the pending callers in a queue and serve them out of the queue in order,When throttling is engaged. While pending in the queue,If the client\'s call timeout expires, the client will get a TimeoutException. 

What is Administrative Endpoint Configuration?

Configuring an endpoint administratively requires placing the endpoints in the hosting process config file. For example, given this service definition:
namespace endname

   interface IMyContract
   class MyService : IMyContract


What is Data Contract Hierarchy?

Data contract class can  be the subclass of another data contract class. Since  the DataContract attribute is not inheritable so WCF requires that every level in the class hierarchy explicitly opt in for a given data contract

class Contact
   public string FtName;

   public string LName;
class Customer : Contact
   public int CNumber;

Define Data Contract Versioning in brief?

WCF needs to enable both backward and forward compatibility, without even sharing types or version information.

There are three main version scenarios:

1. New members
2. Missing members
3. Round tripping, where a new version is passed to and from an old version, requiring both backward and forward compatibility

What is Callback reentrancy?

WCF Interview Questions And Answers