WCF interview question-answer

Posted by imomins on April 3, 2013 at 4:05 AM

What is .NET 3.0?
In one simple equation .NET 3.0 = .NET 2.0 + Windows Communication Foundation + Windows Presentation Foundation + Windows Workflow Foundation + Windows Card Space.

What is WCF?
Windows Communication Foundation (WCF) is an SDK for developing and deploying services on Windows. WCF provides a runtime environment for services, enabling you to expose CLR types as services, and to consume other services as CLR types.

First let us give a short answer to this: - “WCF (Indigo was the code name for WCF) is a unification of .NET framework communication technologies “.WCF is a unification technology,

which unites the following technologies:-
• NET remoting

• MSMQ

• Web services

• COM+.

What was the code name for WCF?
The code name of WCF was Indigo .
WCF is a unification of .NET framework communication technologies which unites the following technologies:-
1.Web services
2.MSMQ
3.NET remoting
4.COM+

What are the main components of WCF?
The main components of WCF are
1. Service class
2. Hosting environment
3. End point

Where we can host WCF services?
Every WCF services must be hosted somewhere. There are three ways of hosting WCF services.
They are
1. IIS
2. Self Hosting
3. WAS (Windows Activation Service)

What is service and client in perspective of data communication?
A service is a unit of functionality exposed to the world.
The client of a service is merely the party consuming the service.

What are different elements of WCF Srevices Client configuration file?
WCF Services client configuration file contains endpoint, address, binding and contract.

What is endpoint in WCF?
Every service must have Address that defines where the service resides, Contract that defines what the service does and a Binding that defines how to communicate with the service. In WCF the relationship between Address, Contract and Binding is called Endpoint.

What are ends, contract, address, and bindings?
The above terminologies are the core on which SOA stands. Every service must expose one or more ends by which the service can be available to the client. End consists of three important things where, what and how:-
• Contract (What)
Contract is an agreement between two or more parties. It defines the protocol how client should communicate with your service. Technically, it describes parameters and return values for a method.

• Address (Where)
An Address indicates where we can find this service. Address is a URL, which points to the location of the service.

• Binding (How)
Bindings determine how this end can be accessed. It determines how communications is done.
For instance, you expose your service, which can be accessed using SOAP over HTTP or BINARY over TCP. So for each of these communications medium two bindings will be created.

Below figure, show the three main components of end. You can see the stock ticker is the service class, which has an end hosted on http://www.soa.com with HTTP and TCP binding support and using Stock Ticker interface type.

What is binding and how many types of bindings are there in WCF?
A binding defines how an endpoint communicates to the world. A binding defines the transport (such as HTTP or TCP) and the encoding being used (such as text or binary). A binding can contain binding elements that specify details like the security mechanisms used to secure messages, or the message pattern used by an endpoint.

WCF supports nine types of bindings.

Basic binding
Offered by the BasicHttpBinding class, this is designed to expose a WCF service as a legacy ASMX web service, so that old clients can work with new services. When used by the client, this binding enables new WCF clients to work with old ASMX services.

This binding is used when we need to use SOAP over HTTP. This binding
can also be configured to be used as HTTPS. It can be also configured to send data in plain text or in optimized form like MTOM.

TCP binding
Offered by the NetTcpBinding class, this uses TCP for cross-machine communication on the intranet. It supports a variety of features, including reliability, transactions, and security, and is optimized for WCF-to-WCF communication. As a result, it requires both the client and the service to use WCF.

This binding sends binary-encoded SOAP, including support for reliable
message transfer, security, and transactions, directly over TCP. The biggest disadvantage of NetTcpBinding is that both server and client should be also made in .NET language.

Peer network binding
Offered by the NetPeerTcpBinding class, this uses peer networking as a transport. The peer network-enabled client and services all subscribe to the same grid and broadcast messages to it.

IPC binding
Offered by the NetNamedPipeBinding class, this uses named pipes as a transport for same-machine communication. It is the most secure binding since it cannot accept calls from outside the machine and it supports a variety of features similar to the TCP binding.

Web Service (WS) binding
Offered by the WSHttpBinding class, this uses HTTP or HTTPS for transport, and is designed to offer a variety of features such as reliability, transactions, and security over the Internet.

It is same like BasicHttpBinding. In short, it uses SOAP over HTTP. But with
it also supports reliable message transfer, security and transaction. WS-Reliable Messaging, security with WS-Security, and transactions with WS-Atomic Transaction supports reliable message.

Federated WS binding
Offered by the WSFederationHttpBinding class, this is a specialization of the WS binding, offering support for federated security.

Duplex WS binding
Offered by the WSDualHttpBinding class, this is similar to the WS binding except it also supports bidirectional communication from the service to the client.

MSMQ binding
Offered by the NetMsmqBinding class, this uses MSMQ for transport and is designed to offer support for disconnected queued calls.

MSMQ integration binding
Offered by the MsmqIntegrationBinding class, this converts WCF messages to and from MSMQ messages, and is designed to interoperate with legacy MSMQ clients.

This binding sends binary-encoded SOAP over MSMQ. This binding can
only be used for WCF-to-WCF communication.

Categories: WCF

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