Top 10 WCF Interview Questions & Answers 2020

   

Q1. Explain how does WCF works?

WCF follows the “Software as a Service” model, where all units of functionality are defined as services.  For communication, each point is a portal or connection either with the client or other services. It is a program that exposes a collection of endpoints.

Q2.  Explain what is the difference between ASMX web services and WCF?

The difference between WCF and ASMX or ASP.net web service is that ASMX is designed to send and receive messages using SOAP over HTTP only. While the WCF can exchange messages using any format over any transport protocol

Q3. Mention what is the endpoint in WCF and what are the three major points in WCF?

Every service must have an address that determines where the service is located, contract that defines what the service does and binding that tells how to communicate with the service.

Address: It specifies the location of the service which will be like http://Myserver/Myservice.  To communicate with our service client it will use this location

Contract: It specifies the interface between the server and client. It’s a simple interface with some attribute

Binding: It decides how two parties will communicate with each other in terms of transport and encoding and protocols

Q4 Mention the address syntax and the different formats of WCF transport scheme?

Address syntax of WCF transport scheme is

[transport]:// [machine or domain] [: optional port] format

Q5. In WCF what are duplex contracts?

Duplex messaging or call-back is used in WCF to communicate with the client. Over different transport system Duplex messaging in WCF is done like TCP, Named pipe and even HTTP.  Collectively this is known as duplex contracts in WCF.

Q6.  Mention what are the different instance modes in WCF?

To a particular service instance WCF binds an incoming message request, so the available modes are

·          Per Call: This instance is created for each call, efficient in terms of memory but need to maintain session

·          Per Session: For a complete session of a user instance are created

·          Single: One instance is created which is shared among all the users and shared among all.  In terms of memory it is least efficient.

Q7. List out the types of binding available in WCF?

The types of binding available in WCF are

BasicHttpBinding

NetTcpBinding

WSHttpBinding

NetMsmqBinding

Q8.Explain what is Data Contract Serializer?

The process of changing an object instance to a portable and transferable format is known as the Serialization, and serialization of data is referred as Data Contract Serializer.

Q9. Mention what are the various address format in WCF?

The various address format in WCF are

·          HTTP Address Format: à http:// local host:

·          TCP Address Format:à net.tcp://local host:

·          MSMQ Address Format:ànet.msmq://localhost:

Q10. What is REST and what is the problem with WCF REST and how it can be resolved?

REST stands for Representational State Transfer, for designing network application REST is used. It relies on a stateless, client server, cacheable communications protocol.  The reason behind creating WCF is to support SOA and not REST. It requires a lot of configuration in order to create HTTP REST service using WCF.  To overcome this tedious task, ASP.NET web API was introduced.