Top 51 WCF Interview Questions And Answers

Introduction

Let  us begin with the wcf full form. WCF stands for Windows Communication Framework, a Microsoft technology that develops scattered and interoperable applications. It also offers the chance to perform  correspondence through several procedures, such as MS informing queuing, services, and remote access. 

Are you interested in WCF and want to pursue a career in this domain? Then you came to the right place. WCF is the abbreviation for Windows Communication Framework, a Microsoft technology meant to develop scattered and interoperable applications. It also offers the chance to perform correspondence through several procedures, such as MS informing queuing, services, and remote access. 

In this blog post for WCF interview questions and answers, we will share frequently asked questions that could help you crack your following interview and immediately get the dream job. You could answer these questions if you have a basic understanding of the technology or worked on the technology before. This blog will work wonders for you.

Big MNCs, including Accenture, Snaphunt, HCL, Infosys, and more, usually ask these questions in their computer programming language interview. You can get a practical understanding of the Cloud, Virtual Machines, Azure Storage, Azure Virtual Networks, Web Service, DevOps on the Cloud, and more with Microsft Azure certification anytime and anywhere.

So, let us move ahead and make your journey enjoyable with a quick list of wcf questions and answers prepared after deep research only.

Why Are Studying WCF Interview Questions Required?

Many companies routinely use WCF, the wcf full form is Windows Communication Foundation, like in computer programming, .NET developers, application programmers, backend architects, etc. So, having command over WCF and confidently answering questions will put you in the top seat, representing you as a well-prepared candidate.

On the other hand, the .NET Framework also allows a developer to produce sharable processes to be cast off in scattered computing patterns. It validates the object-oriented software design structure for multiple languages, including Visual C#, Visual Basic, and others. It also validates and authenticates several programming languages that allow language interoperability. It implies that every language can demand the code enumerated in another language.

WCF Interview Questions with Answers for Fresher

Q1). Explain your understanding of the WCF technology.

Ans:- WCF full form is Windows Communication Foundation. 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 offered interoperability too.

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

WCF's features are endless compared to any other web service. It provides an environment where a particular service is accessible by Windows or Linux clients both. Microsoft has proposed WCF technology, which could be accessed through multiple protocols like HTTP, TCP, MSMQ, and more.

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

Ans:- The framework is suitable for sending asynchronous messages from one endpoint to another. It helps access apps over the internet, whether hosted on the same or a different server. The framework uses a set of APIs to exchange messages between the server and the client.

WCF Fundamentals

• Interoperability
• Unn
• Service Orientation

WCF Architecture

The WCF architecture comprises the following layers – Application Layer, Contracts, Service Runtime, Messaging, Activating, and Hosting.

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

Ans:-

• It is used to exchange messages in 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 performance.
• A service to exchange data securely over the network in real-time.

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

Ans:-

• The framework can be configured to work independently with SOAP or RSS.
• This popular communication technology offers remarkable performance 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 applies to almost all applications that are developed with WCF.

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

Ans:-

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

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

Ans:- SOA means a service-oriented architecture that helps to organize apps as Services. It 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 the counter to the kitchen and be served on your table—the benefits of SOA architecture - Independent, Self-contained, self-explanatory, etc. SOA Architecture consists of four fundamental abstractions – an application front end, a service repository, a service bus, a service, etc. Web services are not SOA but are preferable standards to achieve the SOA. The below image represents the SOA architecture in WCF

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

Ans:- 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 service's data types, protocols, and operation locations. Defining a WCF service contract is difficult, but developers should have the right skills and experience to complete this task.

WCF Interview Questions and Answers for Experienced in .Net

Here are the top wcf interview questions for 10 years experience. Get a clear understanding on WCF and the way it works.

Q16).   What are default Endpoints?

Ans:- WCF offers some default endpoints to the service if a service host doesn’t define any endpoints but has at least one base address. For example, WCF uses the basic binding for the HTTP address. This is an important answer to these kinds of wcf interview questions.

Q17).  What are standard Endpoints?

Ans:- WCF provides a set of pre-defined endpoints known as Standard Endpoints for metadata exchange, discovery, and web. You can configure the standard endpoints by using a config file and programmatically. Here is the list of standard endpoints :

• MEX endpoint
• webHttpEndpoint
• webScriptEndpoint
• workflowControlEndpoint
• announcement endpoints
• discoveryEndpoint
• udpAnnouncementEndpoint
• udpDiscoveryEndpoint

This is an important answer to these kinds of wcf interview questions.

Q18).  What are the different WCF contracts?

Ans:- WCF contract specifies the service and its operations. WCF has five types of contracts:

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

Q19).  What are the various ways of hosting a WCF service?

Ans:- There are four ways of hosting a WCF service.

• Self-Hosting
• Windows services hosting
• IIS hosting
• Windows Activation Services hosting (WAS)

Q20). What is Binding?

Ans:- WCF binding specifies how the service and client will communicate with each other in terms of transport protocols and encoding (such as text or binary). WCF binding is a set of binding elements and each element specify, how the service and client will communicate with each other. Each binding must have at least one transport element and one message encoding element. This is an important answer to these kinds of wcf interview questions.

Q21).   What are the different types of bindings in WCF?

Ans:- WCF supports the following types of built-in bindings:

• Basic binding
• Web binding
• Web Service (WS) binding
• WS Dual binding
• TCP binding
• IPC binding
• MSMQ binding
• Federated WS binding
• Peer Network binding
• MSMQ integration binding

Q22).  What are the ways to create a WCF Client?

Ans:- There are two ways to create a WCF Client or calling a WCF Service as:

• WCF Proxy
• Channel factory

Q23). What is Instance Management in WCF?

Ans:- WCF manages the session by creating the instance of the service class. This created instance(s) to handle the incoming service request. In WCF, the session is the way of managing the services instance(s) so that the server can use these instances in an optimized way. At the server-side, the InstanceContext class is used to manage service class instances. There are following instance management ways :

• Per Call
• Per Session
• Singleton

Q24)  What is Concurrency Management in WCF?

Ans:- Concurrency management is closely related to the Instance management in WCF but both are two different things. Instance management specifies how the service instances are created while Concurrency management specifies how many concurrent requests are handled by the service instances. By using concurrency, you can make your service instance thread-safe. By default, a per-call service instance is thread-safe since each request is served by a new service instance. A per-session service instance is not thread-safe since multiple requests of a client are served by a single service instance. Hence, it’s required concurrency management. A single service instance is not thread-safe since multiple requests of all clients are served by a single service instance. Hence, it’s required concurrency management. 

Q25). What is Impersonation?

Ans:- Impersonation is a way to authorize a caller (client) identity to access the service domain’s resources. The service resources may be local files or database tables and should be on the same machine on which service is hosted. By default, impersonation is disabled and resources are accessed by using the WCF service's process identity.

Q26).  What is service versioning?

Ans:- After the initial deployment of the WCF service, you may need to change the service for a variety of reasons like as changing business needs or fixing others issues. Each change in your existing service introduces a new version of the service. Service versioning is helpful in backward compatibility with your existing clients. 

Q27) What is WCF Data Service?

Ans:- WCF Data Services uses OData (Open Data Protocol) protocol for querying or manipulating the data. WCF Data Services is built on top of WCF REST Services. It is a RESTful service to support CRUD operations on the database using the HTTP protocol. It supports all database operations using URI. DATA protocol can expose data from the relational database, File systems, Web sites, services etc. It supports XML or JSON format for exposing the data. 

Q28).  How is SOA beneficial?

Ans:- SOA forges more dedicated applications because it's more effortless to debug small services than large code. Scalability. SOA lets service run on different servers, increasing scalability. In addition, using a standard communication protocol allows organizations to reduce the level of interaction between clients and services.

Q29). What is the difference between ASP.NET Web Services and WCF

Ans:- 

WCF	ASP.NET Web Services
To define WCF services service contract and operation contract attributes are used	To define ASP.NET Web services, webmethod attributes are used
This is hosted in IIS, WAS, Window service,	Hosted only in IIS
Support protocols like TCP,HTTP,HTTPS,MSMQ	Supports only HTTP, HTTPS
Supports data contract	Supports XML serializer

Q30). What are the isolation levels offered in WCF?

Ans:- The isolation levels provided by WCF include the following:

• Read uncommitted: The Dirty isolation level denotes that the data can be read and altered during the transaction. It constitutes the lowest stage of the transaction.
• Read committed: The default level signifies that the data may be altered but not read during the isolation.
• Repeatable Read: This prohibits the utilization of dirt reads and signifies that the data can be read but can’t be altered, but new data can be added.
• Serializable: This is a restrictive level that denotes the data can be read, but the transaction needs to be finished to allow further alterations and additions of new data.

Read the top 40 WPF Interview Questions and Answers!

Q31). What is meant by service proxy?

Ans:- WCF proxy classes allow client applications to interact with services by delivering and receiving messages. It constitutes information like the Service Path, Protocol Details, and others. The interaction process also includes exchanging messages through individual requests and responses. The service proxy is a class that reveals the service contract. The service Proxy includes the service contract tasks and a few extra operations to control the proxy process and the association with the service. 

Q32). What do you mean by Tracing in WCF? 

Ans:- WCF tracing offers an analysis of data and erroneous messages. It offers an extensive synopsis of the application components comprising faults, code exceptions, system events, and operation calls. Tracing also provides deeper insight into the application’s behavior and flows rather than debugging the same.

WCF tracing includes the four vital stages of emitting trace information from service, defining the trace level, linking the listener, and activating message logging. However, WCF tracing is not activated by default. Hence, it should be activated by linking it with the switch value and trace listener.

Q33). What is meant by Security Implementation?

Ans:- WCF supports several protocols like TCP< HTTP>and MSMQ. WCF offers a smooth and proper configuration surrounding promoting safe messaging. Hence the user should guarantee the utilization of appropriate methods to protect the messages and create security protocols for validating and authorizing calls. The security models supported by WCF include the following:

• Message Security:-  This model utilizes the WS-Security specification to safeguard messages. Messages are safely encrypted through authentic documents and can be delivered over any port through simple HTTP.
• Transport Security: This policy focuses on security; hence, it works from one point to another. Security is reliable on policies, so security support is restricted to the traditional protocol security boundaries.
• Transport With Message Credential:- This is a blend of Message and Transport security protocols. Authorizations are delivered with the message, and the transport stage offers safe messaging and server validation.

Q34). What are the various types of transaction managers supported by WCF?

Ans:- The three kinds of transaction managers supported by WCF comprise:

• Light Weight
• WS- Atomic Transaction
• OLE Transaction.

Q35). Explain the various instance modes in WCF.

Ans:- WCF offers three methods to manage WCF instance creation:

• Per Call: A fresh instance will be made for every request from the previous or a new client, which implies that each request will be fresh. However, a session must be maintained, although this mode is very effective for memory.
• Per Session: A fresh instance would be made for every new client session, and the extent of that object will be directly related to the range of the session.
• Single Instance: Only a single instance will be made for every service object request. The instance will be created irrespective of being achieved from the previous or a new client. It is a comparably ineffective instance mode for memory utilization. 

Q36). What is meant by WCF throttling?

Ans:- Throttling is obtained from the keyword throughput, which implies the task that is executed at certain intervals of time. The efficiency of task performance is also escalated by utilizing it. The count of instances or sessions generated at the application stage can be restricted by utilizing the features like maxConcurrentCals, maxConcurrentInstances, and maxConcurrentSessions offered by WCF throttling. 

Q37).  Explain what you understand by Streaming.

Ans:- WCF allows the relocation of images, pdf files, and huge documents. Streaming comprises the most suitable procedure to attain this. It enables the receiver to start processing the message before it has finished getting the whole message. Streamed transfers also emphasize that there is no necessity to maintain huge memory buffers in the background, thereby upgrading scalability.

Q38). What are MEPs in WCF?

Ans:- MEP is the abbreviated form of Message Exchange Pattern. MEP comprises the best characteristics of WCF. It is a process of interaction between clients and servers in WCF. 

There are three kinds of MEPs that WCF supports:

• Request-Reply- Request-Reply is the default interaction style supported by WCF>
• One-way- This pattern implies that you don’t consider getting a reply back from the client after it executes a specific task.
• Duplex: This is a two-way interaction process used when the client begins a lengthy method with the service, and the service demands notification.

Q39). What do you understand by MSMQ?

Ans:-MSMQ stands for Microsoft Messaging Queue. It is a technology utilized for asynchronous interactions and is effective for inter-process interaction. MSMQ is helpful when two methods want to interact in a Fire and Forget manner. It was created by Microsoft and is used in the Windows Operating System.

MSMQ allows smooth interaction over heterogeneous networks and offline systems at specific periods. 

Q40). Explain Fault Contract in WCF.

Ans:- Fault Contract offers a documented view for faults granted in the service to the client. It promotes easy detection of the error that has occurred ad the respective location of the error. When an exception is thrown from the service by default, it won’t get delivered to the client. The communication will be vague if the client doesn’t know much about the issue on the server side. Error masking is not letting the exact reason for fault reach the client. 

Every exception thrown on the server side gets delivered to the client by default as FaultException, because by having the service exceptions identical, WCF segregates the client and service. A Fault Contract can be implemented in the following way, as shown in the image below.

Q41). What do you mean by REST, and explain the issue with WCF REST?

Ans:- REST is the abbreviated term for Representational State Transfer. It is used to create network applications and depends on a stateless, client-server, cacheable interactions protocol. The cause of designing WCF is to assist SOA (Service Oriented Architecture). 

It needs extreme configuration to design HTTP REST service through WCF. However, ASP.NET web API was launched to eliminate this hectic work.

Q42). What do you mean by Information cards in WCF?

Ans:- Information cards are virtual depictions of an individual’s identity that a particular group guarantees. The cards resemble real-world identity cards like passports, licenses, and credit cards. 

Certain advantages accompany Information cards, like

• Authentication.
• Validation
• Decrease IT stress
• Offering reliability to fields
• Enables maintenance of security.

Q43). What do you understand by Method Overloading in WCF?

Ans:- Method Overloading refers to the feature that produces various procedures with an identical name. Every procedure must be distinct from the others regarding input and output functions. Two methods can’t possess identical type parameters. They can vary in the count of parameters or the type. Method Overloading can also be referred to as a compile-time polymorphism because the calling procedure is aware of the address of the called procedure, and the method addresses are settled during compile time. Another term referring to this is Early Binding. 

Q44). Mention the advantages and disadvantages of self-hosting.

Ans:- The advantages of self-hosting include:

• Simple to use: Some lines of code can run your service.
• Flexible: This feature allows you to manage the lifetime of the services with the help of the Open() and Close() procedure of ServiceHost.
• Simple to debug: Sorting WCF services hosted in a self-hosted surrounding offers a friendly debugging manner without linking with different applications that enable the service.
• Can be used efficiently: There is no requirement for an intricate deployment structure on server farms to use a Windows application that works as a WCF ServiceHost.

The disadvantages comprise the following:

• Restricted availability: Self-hosting is available only when running the application.
• Restricted features: The services have finite assistance for high availability, smooth controlling, strength, recoverability, versioning, and utilization objectives. WCF doesn’t offer these. Hence you must use the features in a self-hosted environment. 

Q45). What do you mean by DataContractSerializer?

Ans:- WCF offers a message-oriented structure for programming. WCF is utilized to convey messages between applications. It portrays all the messages by a Message class. While transferring a message, WCF picks a logical message object and codifies it into a series of bytes. Then WCF reads the bytes and decodes them within a logical object. The method transforms a series of bytes into a logical object known as the encoding method. While running the application, WCF converts the logical message to respective .Net objects. This method is termed serialization. 

The three prime serializers supported by WCF include:

• XMLSerializer
• NetDataContractSerializer
• DataContractSerializer

WCF offers DataContractSerializer by default, accompanied by a service contract. This can be modified to a personalized serializer such as XMLSerializer.

Q46). Explain the four Service Oriented Design Principles.

Ans:- The four Service Oriented Design principles in SOA include:

• Restrictions are precise: This principle denotes that a service can be used irrespective of the place and can be smoothly accessed by others, irrespective of the surrounding of the other services.
• Services are free: This principle indicates that every service should be controlled distinctly so they don’t influence other services in the cycle. A contract, once created, must not be modified, and services must be segregated to achieve the target to make them freely available.
• Services share schema and contract: This principle indicates that services must not undergo classes but data and contracts. This offers a vaguely associated system where the service does not bother about the kind of environment the other service is executing on. The data being handed over is entirely platform-independent. 

Q47). Define WS -* protocols?

Ans:- The SOAP protocol is utilized for message transference between Web Services. However, SOAP underlines the fundamental semantics for message headers. It does not provide meaning to the header. So WS -* protocols have been created with semantics that can be utilized in several application environments.

WS-* protocols refer to a range of rules and obligations that allow us to perform specific demands and behaviors of a service. These standards depict how to safely and adequately convey messages using the SOAP message's headers. WCF can perform the WS -* protocols through WsHttpBinding. This utilizes a few WS -* protocols and provides the required behaviors, including transactional message calls, reliability, and addressing. 

Q48). What do you mean by WCF ABC?

Ans:- The WCF ABC constitute the Address, Binding, and Contracts. The address refers to the actual place where the host is situated. Binding is the interaction process between the client and the service through encoding and transport standards. The actual content of the service is specified in the contracts. 

Furthermore, contracts are what the service will share with the external environment. Several attributes constitute the service, including ServiceContract, OperationContract, DataContract, and MessageContract. On the other hand, the address depicts schemes, MachineName, Port, and Path. Lastly, bindings are divided into three categories, namely HTTP-based, TCP-based, and MSMQ-based binding.

Q49). What are the benefits of Transport Level Security?

Ans:- Transport-level Security offers security, validations, and integrity. The various benefits of Transport Level Security include the following:

• Decreased chance of Phishing Networks
• Less probability of Sniffing Networks
• Fewer chances for message modification.
• Less chance of a replay of the message.

Transport Level Security validates the service and sender, message privacy, message coherence, and replays the message identification. 

Q50). How will you define Transaction propagation?

Ans:- Transaction Propagation can spread the transaction over the boundaries of a single service. The service can take part in the transaction that the client has begun. However, transaction propagation becomes a prime necessity in the SOA scenario. WCF validates SOA and assists in transaction propagation. 

Transaction Propagation can be facilitated by confirming the value of the transaction property of the binding. It can be done programmatically in a below-mentioned way:

WSHttpBinding bindingBeingUsed = new WSHttpBinding();
bindingBeingUsed. Transaction Flow = "true";

Q51). What is meant by KnownType Attribute?

Ans:- The KnownType Attribute class allows us to state the types that should be discussed for concentrating on the deserialization. Usually, the WCF service takes and sends a base type. However, if we assume the service to take and send the inherited type next, the KnownType Attribute is utilized.

The KnownType Attribute is also used while we predict the service to get and send the inherent type while sending the parameters and returning the values between a service and the client. Both endpoints share each data contract of data to be delivered while sending parameters and returning the values between the client and the service. 

Conclusion

WCF is still a framework that allows you to design extremely sophisticated solutions and manage all parts of your data flow. It remains a necessary skill for any senior.NET developer. If you're preparing for a WCF interview, these questions and answers will help you ace the interview and get the job. WCF is a powerful framework for developing web services, and these questions will test your knowledge of the core concepts. Be sure to brush up on your wcf interview questions and answers before the interview to impress your interviewer and land the job. You can also check out interview questions on Microsoft Azure for an upper hand. Thanks for reading!

Frequently Asked Questions (FAQs):

Q1. How are WCF interview questions necessary to help reach the ultimate goal?

Ans:- WCF is a brilliant career scope for those willing to establish themselves as computer programmer, software developer, or .NET developer. Hence the set of WCF interview questions and answers will provide you with all the details related to WCF and the probable questions that can come to help you prepare for the exam and ace it in the first go.

Q2. What is the benefit of cyber security training online? 

Ans:- Cyber Security training & certification  enables the individual to comprehend the value of cybersecurity and imparts knowledge to detect probable danger and act accordingly and quickly. The Cyber security training course also offers the workers the required insight and potential to detect, report and evade security mishaps. 

Q3. Mention the possible career scope that one can get after attending Cyber Security training classes.

Ans:- The Cyber Security training classes defend a company from cyber crimes on the computer application leading to data loss. The main aim is to stop the events that degrade the brand image and cause financial disruption. The multiple career options that the cyber security training course brings with it include Security Analyst, Security Engineer, Security Architect, Security Administrator, Security Software Developer, Cryptographer, and Security Consultant. 

Q4. What are the prerequisites to enroll for the cyber security training online?

Ans:-  Cyber Security training & certification requires you to attain a 4-year bachelor’s degree in computer science, information science, or computer programming. Apart from this, English, statistics and maths are required to receive the training.

Q5. What is the distinction between WCF service and Web API?

Ans:- WCF is utilized to create SOAP-based services, but Web API is utilized for SOAP-based and  RESTful services. WCF does not provide any assistance for MVC characteristics, but Web API supports MVC characteristics. WCF supports HTTP, UDP, and personalized transport standards, but Web API assists protocol. 

Q6- What is the wcf full form, and where is it utilized?

Ans- WCF full form is Windows Communication Foundation (WCF), a framework for building service-oriented applications. By utilizing WCF, you can send data as asynchronous messages from one service endpoint to another. A service endpoint can be part of a continuously unrestricted service hosted by IIS, or it can be a service hosted in an application. It is a very common question in interview questions wcf.

Q7 What is the difference between WPF and WCF?

Ans- The difference between WPF and WCF is that WCF deals with communication (in simple terms - sending and receiving data and formatting and serialization involved), and WPF deals with presentation (UI). One of the important interview questions wcf

Q8 What is the market report on WCF?

Ans- It is estimated that almost 4,524 companies use Windows Communication Foundation. The companies using Windows Communication Foundation are most often found in the United States and the Information Technology and Services industry. 

Q9- What are the top industries using wcf?

Ans- If you look for  Windows Communication Foundation customers by industry, we find that Information Technology and Services (26%), Computer Software (13%), and Financial Services (6%) are the most significant segments.

Q10 What are the top countries using wcf and distribution of companies that use Windows Communication Foundation based on company size?

Ans- 62% of Windows Communication Foundation customers are in the United States, and 5% are in India. Of all the customers that are using Windows Communication Foundation, 21% are small (<50>37% are medium-sized, and 42% are large (>1000 employees).