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WCF Interview Questions and Answers

WCF Interview Questions and Answers

September 14th, 2019

WCF Interview Questions and Answers

In case you’re searching for WCF Interview Questions and Answers for Experienced or Freshers, you are at the correct place.  Additionally WCF Online Training educates about the services supported with WCF such as hosting services, asynchronous calls, transaction management, instance management, and queed calls. WCF enhances the security, alter binding and enhances interoperability among the services. In this WCF Online Course, learners are engaged with interesting topics like addresses, bindings, service contracts, data contracts, instance management, and handling errors. Countries in which WCF largely used are United States, United Kingdom, India and Canada. The demand for WCF is assessed with global market and domestic market.

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Best WCF Interview Questions and Answers

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Q1) What is the full form of WCF?

Answer: The full form of WCF is the Windows Communication Framework.

Q2) Which was the initial code name for WCF?

Answer: The initial code name for WCF was Indigo.

Q3) What is the primary function of WCF?

Answer: To make the communication between various processes in a given system easier is the main function of WCF.

Q4) What are some of the other purposes WCF serves as well?

Answer: WCF is also used for other functions like queuing, services, MS messaging and remoting.

Q5) With WCF can one communicate with other non-Microsoft applications also?

Answer:  Yes, one can communicate with other non-Microsoft applications like J2EE as well.

Q6) State the three main components of WCF.

Answer: The three main components of WCF are as follows… endpoints, hosting environment and service class.

Q7) What is the model of functionality that WCF follows?

Answer: The model of functionality that WCF follows is… software as a service.

Q8) How does software as a service work?

Answer: The way this model works is that each point is a source of connecting either with a client or with any other services involved. Thus as a program, it shows a collection of endpoints.

Q9) State the main difference between ASMX web services and WCF.

Answer: The main difference between the aforementioned two systems is that the former can send & receive messages only via HTTP and the latter can do so with any format over any protocol.

Q10) State the three main points in WCF.

Answer: The three main points in WCF are as follows… binding, contract, and address.

Q11) State the types of contracts in WCF.

Answer: The types of contracts in WCF are as follows…service contracts, data contracts, fault contracts, message contracts.

Q12) State some of the transport schemes that WCF contains.

Answer: Some of the transport schemes that WCF supports are as follows… HTTP, TCP, IPC (inter-process communication), MSMQ and Peer Network.

Q13) What are some of the ways to host a WCF service?

Answer: Some of the ways to host a WCF service are as follows… IIS, self-hosting, and WAS (Windows Activation Service).

Q14) State which are the different instance modes in WCF?

Answer: The different instance modes in WCF are as follows…per call, per session and single.

Q15) What do you understand by Service Proxy in WCF?

Answer: The main function of a service proxy is to help the various applications send and receive messages. It’s an aspect that encompasses aspects like service path, platform, communication protocol, and service implementation technology.

Q16) What is the full form of SOA

Answer: The full form of SOA is Service-Oriented Architectural.

Q17) What is the function of SOA?

Answer: The main function of SOA is to decipher how two computing entities will work best with each other to gain business optimization and also how individually if both entities can work on behalf of each other.

Q18) State the types of data contracts in WCF

Answer: The types of contracts in WCF are as follows… Data Contract and Data Member

Q19) Mention the three types of transaction managers that WCF contains.

Answer: The three types of transaction managers that WCF has are as follows…Light Weight, WS-Atomic Transaction and OLE Transaction.

Q20) What is the full form of MEP?

Answer: The full form of MEP is the Message Exchange Pattern.

Q21) State the types of MEPs which are available in WCF.

Answer: The three types of MEP which are available in WCF are as follows…Data Gram, Request and Response, Duplex.

Q22) Which is the namespace used to access WCF?

Answer: The namespace that is used to access WCF is known as System.ServiceModel

Q23) State the types of binding that WCF encompasses.

Answer: The different types of binding which are there in WCF are as follows… BasicHttpBinding, NetMsmqBinding, NetTcpBinding and WSHttpBinding.

Q24) What do you understand by the data contract serializer?

Answer: When the format of an object is changed to a transferable and mobility induced one, it is known as serialization. When data is serialized, it is known as data contract serializer.

Q25) What is the full form of REST?

Answer: The full form of REST is Representational State Transfer.

Q26) In WCF what are the various isolation levels which are given?

Answer: The various isolation levels in WCF are as follows… Read Uncommitted, Read Committed, Repeatable Read and Serializable.

Q27) State the contract that is used to rectify errors in WCF

Answer: The contract that is used to correct mistakes is known is Fault Contract.

Q28) Define WCF? How does it work?

Answer: WCF is a program for generating the services application. To make the interaction convenient from MS messaging, remoting, Queuing, services, .NET and j2EE. It is very easy to use on protocols such as HTTP, TCP, msmq. Conveying the data from one to other customers.

Q29) What is used to design the application of the network? Define

Answer: Representational State Transfer, It is a way to give standards to protocols on the online for PC conversation. It is used to define resources, changing the information, scalability, data items.

Q30) Define SOA?

Answer:It is a group of methodologies and principles to design and develop the software. It is a group of services to regulate the computing entities. It is to interact with one another on various platforms and languages.

Q31) Why Duplex contracts are used in WCF?

Answer: Single way contracts to communicate independently with the client. It is a channel to send back the message to the customer on various transport platform.

Q32) Why we use information cards in WCF?

Answer: To increase the application of WCF we apply the DerivativesCalculator sample. It is considering as the actual identity like credit cards, employee ID cards, passports and driver licenses. There are many advantages to attach the information card such as

  • Decrease the pain of IT
  • Helps in Authorization and authentication
  • Manages the security level and allows believe in domains

Q33) What is the set of techniques in WFC?

Answer: Instant management is the set of techniques that tie up the customer’s appeal for immediate services, It is a way for deciding, when and which services instance will serve a client.

Q34) What is a formal agreement in WFC?

Answer: Data contract is known as a formal agreement. It is an agreement between the client and the service to exchange data. There are two types of data contracts. It regulates the modification of the formate of data.

  • Explicit – It is complex describes the user item. By using DataContract and DataMember attribute to explain Data contract.
  • Implicit – Int, string are simple called implicit data.

Q35) What is the packet of data in WFC?

Answer: In WFC, a message is the packet of data. It is for moving the message from one origin to station. Simple Object Access Protocol is for interacting includes header, body and envelop, We can also personalize the parameters by SOAP.

Q36) Explain KnownType Attribute?

Answer: We can define in advance the type of consideration at the time of deserialization. The endpoints of client and service share the data contract for transfer at the time of returning values and parameters.

Q37) What is needed to hold an error/exception?

Answer:A Fault Contract, is used to manage the client to try and catch blocks. SQL Server does not respond when the customer calls the service class. FaultExpection class is supported by SOAP Faults.

Q38) Describe Service proxy?

Answer: An application to communicate by sending and receiving messages with features such as service path, platform, the interaction of protocols, services, achieving automation. It is like the interaction of local items, at the time of application is communicating the service.

Q39) What is to check the instances?

Answers:In WFC, throttling gives few properties to build the size of an application to grow the production. It also checks the concurrent calls and sessions.

Q40) What is used to create an n-tire application?

Answer: Ria services, It is for standard versions and action to create a difficult business application in Silverlight, AJAX by the validation from the client-side. It is also the perfect solution to ASP.NET and Silverlight by connecting them.

Q41) How to interaction happens between client and server?

Answer: By using a message exchange pattern. It helps to send a reply on request. In this, a message is considered as the request and also receives a message for a reply. There are three types of MEP. Duplex, one-way and Request-Response.

Q42) How to create multiple methods in the same name?

Answer:By method overloading, the method must be different from each other in the output and output of the function. It is also known as a compile-time polymorphism. The number or type of parameters must be distinct from each other.

Q43) Who provides the configuration? For what

Answer: Endpoints for transmission to construct the application for WFC services. It is used for sending and receiving messages such as binding, address, and contract.

Q45) Name the contract? Define the service contract in WFC?


  • Service contract
  • Operation contract
  • Fault contract
  • Data contract
  • Message contract

The service contract is the operation to deliver services. Services have many service contract but one service contract is a must. It includes the setting like the service name and namespace.

Q46) In which format do we need WFC services for the business?

Answer: In the format of XML for exchanging the messages, To maintain interoperability we need HTTP protocol.

  • In the binary format for exchanging the remote services, to maintain the performance we need TCP protocol.
  • And we can exchange our data privately on the network.

Q47) What is a logical unit in WFC?

Answer: The transaction is considering as the logical unit to describe the multiple activities such as fail or pass. At the time of online order, a transaction gets active. Atomic and long-running are two types of transaction and they are Prepare and commit phase.

Q48) Why a WFC service host in WAS?

Answer: This allows the service for interacting by various protocols. And used to fix the IIS 7.0 to create for the Windows Vista. The services are for HTTP and non-HTTP protocols. We have to attach the reference to the services for the application of the clients.

Q49) Explain the message layer in WFC?

Answer: The message layer contains 8 channels to tell the formats and data interchange for interacting. To act on messaging, operating messaging and the header of the message. The two categories are

  • Transport is used to read and write a message online
  • Protocol channels are used for applying the message by protocols.

Q50) Name the protocols of WFC? And where they are used?

Answer: The protocols are

  • Ws- Security
  • Ws- Reliable messaging
  • HTTP
  • TCP
  • Encodes
  • Transaction flow
  • Named pipe
  • MSMQ

They are used in the Message layer.

Q51) Explain Impersonation?

Answer: It gives permission to connect the means of the service domains. It can be information tables or native files on the machine where service is hosted. The services process identity is used when the means are accessed and Impersonation disables.

Q52) What is used for questioning or operating the data by WFC Data services?

Answer: OData Protocol is used. Data service is created at the peak of the WFC Rest service. The RESTful service handles CRUD operations by the use of HTTP protocol. By the use of URI, it helps all the database. DATA protocol uncovers data from the file system, services Web sites and relational database. And also maintains the format of XML or JSON to show the data.

Q53) What is needed for backward compatibility?

Answer: Service versioning is used for backward compatibility for the current customers. For the modification of the service for the uncertain needs of the occupation or to solve an issue after the primary deployment of the WCF service.

Q54) Describe Concurrency Management? And its types?

Answer: It is used to handle multiple threads and to command by the System.ServiceModle.ServiceBehaviourAttribute. It identifies the number of concurrent requests is hold by service instances and to make thread-safe. Types are  Single, Multiple, Reentrant concurrency Mode.

Q55) Define Instance Management?

Answer: A group of messages on the client request for immediate service is considered as Instant management. It is used to support the incoming service request and the management of services. These are three ways for Instant management?

  • Per call
  • Per Session
  • Single

Q56) Define Endpoints?

Answer: By the use of endpoint WCF gives the services to the customers. Endpoints give the important means and the guidance to the customer for interacting with different services.

Q57)Tell the various transport of Duplex contracts? Define

Answer:Duplex messaging is for interacting with the customer by call back process. Various transport such as HTTP, TCP, named pipes. A customer and servers can independently interact with each other by one way and Request-Reply contract.

Q58) Define Binding in WFC?

Answer: Binding tells us about the manner in which the service and the customer will interact with one another by binary or text A binding should have a transport element ad a message coding element.