WCF Interview Questions with Answers for Fresher

WCF Interview Questions with Answers for Fresher

Q1). Explain your understanding of the WCF technology.

WCF is a platform for building distributed apps or services among multiple endpoints in Windows. The initial name for WCF was Indigo and it was designed for building service-oriented apps and offers interoperability too.

The WCF is abbreviated as Windows Communication Foundation; this is a popular programming model that is suitable for designing service-oriented apps. It can be used to create or deploy services that are easily accessible by multiple clients worldwide.

It provides an environment where a particular service is accessible by windows or Linux clients both. The features of WCF are just the endless when compared to any other web service. WCF technology has been proposed by the Microsoft and it could be accessed through multiple protocols like HTTP, TCP, MSMQ and more.

Q2). Explain the WCF fundamentals and its architecture in brief.

The framework is suitable for sending asynchronous messages from one endpoint to another endpoint. The framework is using a set of APIs to exchange messages between the server and the client. It helps in accessing apps over the internet either it is hosted on the same server or different server.

WCF Fundamentals

• Interoperability
• Unification
• Service Orientation

WCF Architecture

The WCF architecture is made up of the following layers – Application Layer, Contracts, Service Runtime, Messaging, Activating, and Hosting.

Q3). What is the need for WCF services for your business?

• It is used to exchange messages in the XML format with the help of HTTP protocol to maintain interoperability.
• WCF uses remote services to exchange messages in binary format with the help of TCP protocol to maintain the performance.
• A service to exchange data securely over the network in the real -time.

Q4). What are the benefits or advantages of WCF Technology? 

• The framework can be configured to work independently with SOAP or RSS.
• This a popular communication technology that offers remarkable performance when compared to other Microsoft specifications.
• This framework is suitable for secure communication, data transmission, and even speed can be optimized. It is exchanging data in binary format to decrease the latency.
• This is a distributed management system that is applicable to almost all applications that are developed with WCF.

Q5). How will you distinguish the WCF from other web services?

Web Services	WCF
They can be hosted in IIS only.	It can be hosted in IIS, windows service, self-hosting and more.
Here, you need to add a <Web Service> attribute to the class.	Here, you should add a <Service Contract> attribute to the class.
The duplex operation is not supported in the case of web services.	The duplex option can be supported freely in the case of WCF.
Data can be exchanged using the HTTP protocol only.	Data can be exchanged with HTTP. TCP, MSMQ and more.
XML and Custom Encoding	XML, Custom, Binary, MTOM
Security	Secure, reliable messaging, transactions etc.

Q6). What do you mean by SOA? Do web services come under SOA?

SOA means a service-oriented architecture that helps to organize apps as Services. This is a group of methods that define the business logic and helps to connect with DB and other services quickly. Take an example of the restaurant where you go and order food. Your order will go from counter to the kitchen and it is served on your table finally.

The benefits of SOA architecture – Independent, Self-contained, self-explanatory etc.

SOA Architecture – It consists of four key abstractions – an application front end, a service repository, a service bus, a service etc.

Web services are not SOA but preferable standard to achieve the SOA.

Q7). How will you define the service contract in WCF?

The Service Contract is a collective mechanism where the capabilities and requirements of service are specified for its consumers. It will explain the list of operations that will be performed by the service when it is executed. It will define the data types, protocols, and operation locations for the service. Defining a service contract for WCF is not easy but developers should have the right skills and experience to complete this task.

WCF Interview Questions with Answers for Experienced

Q8). What do you mean by contract in WCF? Explain the type of contracts too.

The main objective of defining contracts is to make agree with both client and server for the same operations, structures, data types etc. This is important to establish the secure communication between the two. This is a formal agreement to define the platform neutrality and standards as well as what is done by the services. Here is given most common types of contracts that are frequently used within WCF technology.

• Service Contract
• Operation Contract
• Data Contract
• Message Contract
• Fault Contract

Q9). How will you explain the data contract in WCF?

A data contract is a formal agreement between the server and the client between whom data is exchanged securely. It could be defined either implicitly or explicitly based on the requirement. It will define the format, structure, and type of data to be exchanged between parties. It will define the process how can data be serialized or deserialized. This is a versioning system that helps to manage changes for structural data.

[DataContract]

Public class cuboidInfo

{

}

Here, in the example, we have given the general syntax for the data contract. It will provide the complete data abstraction at a new level like never before.

Q10). How will you define the message contract in WCF?

The objective of message contract in WCF is to define the structure for the message and how can you perform the serialization. By default, it will take care of SOAP messages based on service requirements. Here is given the general syntax for message contract in compact form –

[MessageContract]

Public Class AutherRequest

{

Public String AutherId;

}

Q11). What are the endpoints in WCF? Explain its common types too.

Endpoints are responsible to provide the necessary configuration and help1101 in creating the complete WCF application too. It will define the complete piece of information how can you exchange the data between two points. It consists of three major parts – address, binding, and Contract. The basic structure of endpoints in WCF is shown below in the diagram –

• Address uniquely identifies each end point.
• The binding will specify how clients can communicate with endpoints.
• The contract will identify the list of available operations.

All communications in WCF has to pass through service endpoints so that data can be exchanged securely as needed by enterprises.

Q12). What is the need of Address when defining service endpoints in WCF?

If you are not sure where to send messages then addresses play an important role here. This is a Uniform Resource Locator (URI) that will identify the location of the receiver. It is similar to the network address and highly useful to send or receive messages. It can be divided into four parts – Scheme, Machine, Port, and the path. Each address is unique in itself and finds out the location of receiver accurately without any error. There are a plenty of protocols are used to exchange messages in WCF. These are HTTP, TCP, MSMQ etc.

Q13). What is binding in WCF? Explain its characteristics too.

The Binding will explain to you how will you communicate with the service. There are a plenty of protocols to facilitate communication in WCF. These are HTTP, TCP, MSMQ etc. The characteristics of binding are Protocol, Encoding, or Transport etc.

Q14). What are the transactions in WCF? Explain its types too.

A transaction is a logical unit that defines multiple activities in WCF either pass or fails. The two common types of transactions are – Atomic and Long Running. Two phases of transactions are Prepare Phase and the Commit Phase.

Q15). What are the hosting requirements for a web service?

The hosting requirements for a web service include – Availability, Reliability, Manageability, Versioning, Deployment, State etc.