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Web Service Interview Questions and Answers

Simply put, net Service is outlined as a technique of communication between any 2 electronic devices through the World Wide Web (www). These net Services are unit XML (eXtensible Markup Language) primarily based data systems that use the net for straight application to application interaction. XML is employed to write all styles of communications to net service. Because the net services use XML communication, they’re not restricted to 1 software package or programming language- Windows will converse with the operating system and Java with Perl.

Web services are unit independent, modular, distributed and dynamic which might be delineated, published, settled or perhaps invoked over the network to form merchandise, processes and provide chains. Net service may be a compilation of open protocols and standards used for commercialism data between applications or systems. Totally different  software system applications written in miscellaneous coding languages that area units run on different platforms might create  use of net services to exchange knowledge over a large variety of laptop networks like however net is that the means for writing up on one laptop. The interoperability between 2 platforms for e.g. between windows and operating system, is thanks to net services.

Low price communication is one among the benefits of net services, conjointly the explanation why net services like Java net service, net api services, amazon net services area unit extensively used.

Web services hold much importance in the technical round of a software interview, if you want to ace the interview. So, In this article, all basic concepts on Web Service  are covered for which you must be well acquainted, in order to answer any echelon questions asked in the interview. You will also see the most commonly asked web services interview questions and answers in categories so that you will get an idea of what and how it is asked.

Components Of Web Service

The contents of a basic net service embody XML and hypertext transfer protocol (HyperText Transfer Protocol) however the quality net services conjointly in addition have the following:

  • SOAP (Simple Object Access Protocol)
  • UDDI (Universal Description, Discover and Integration)
  • WSDL (Web Service Description Language)

 How will A Web Service Work?

A Web Service permits communication between varied applications by victimisation open standards like markup language (Hyper Text Markup Language), XML, WSDL (Web Service Description Language) and SOAP, every play a unique role in commercialism the data:

  1. XML tags the info.
  2. SOAP transfers the message.
  3. WSDL describes the supply of the service.

Process of however it works:

1) The consumer program combines the account registration data into SOAP messages.

2) This SOAP message is then sent to the online Service because the body of the associate hypertext transfer protocol POST request.

3) The net Service unpacks the SOAP request then converts it into a command during a manner that the appliance will perceive.

4) The application processes the knowledge as desired, meeting the requisites and responds with a brand new distinctive account range for that client.

5) Next, the online Service packages the response into one more SOAP message that is shipped back to the consumer program in response to its hypertext transfer protocol request.

6) The consumer program unpacks the SOAP message to accumulate the results of the account registration method.

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Real World Application of net Services:

Amazon web Services give costs for the merchandise they show and sell on-line via Amazon.com, the front that is additionally called the presentation layer is either .Net or Java however they need to own the power to speak with the online service.

o Travel search sites depend upon net services to search out the simplest possible travel deals. They use net services to fetch knowledge from varied travel sites, and then mix and reason supported totally different filters and lay it before their customers.

o Email Service suppliers (ESP) make use of net service to include different software systems.

Application based concepts are what is important because they are the most asked web services interview questions because it is not enough if we know the theoretical aspect of it and we ought to master the practical usage of web services in real world, so without a doubt, this is one of the most important asked web services interview questions

Types Of Web Services:

There are essentially 2 styles of web services:

  • RESTful (Representational State Transfer) net Service.
  • SOAP net Service.

RESTful net Service, developed by Roy Thomas Fielding, World Health Organization is additionally the developer of hypertext transfer protocol. Main expression of reposeful net services is to produce additional potency by redefining the services that area units already give in hypertext transfer protocol. REST is outlined as an associate beaux arts approach and isn’t a protocol. REST isn’t outlined by the quality Message exchange format. One will build REST services with each XML and JSON (Javascript possibility Notion). Among JSON and REST, the previous is most popular. In REST, the key abstraction may be a resource. A resource is something, which might be accessed through an even Resource symbol (URI).

Constraints of RESTful:

  • The presence of a service supplier and a service shopper is a must
  • REST is homeless and must be cacheable.
  • The interface of REST is uniform and exposing resources.
  • The Service should assume a bedded design.

Advantages of RESTful Service:

  • RESTful net Services area unit platform freelance, i.e. they will be written in any artificial language and may be dead on whichever platform.
  • RESTful is written victimisation any artificial language and may be dead on any platform
  • RESTful provides totally different knowledge platforms like JSON, text, markup language and XML.
  • When compared to SOAP, reposeful is quicker as a result of it’s not restricted to 1 specification.
  • RESTful is reused and language neutral.

SOAP net Service

SOAP stands for Easy Object Access Protocol, may be an electronic communication rule merely for commercialism planned data within the performance of net services within the world of laptop networking. It solely uses XML data set for its message format. SOAP permits developers to say processes during a row on totally different in operation systems like Windows, macOS etc to validate, allow, and communicate victimisation XML. It’s associate XML-based protocol that consists of 3 parts:

  1. Associate envelope that defines the message structure and tells however it works.
  2. List of coding rules for expressing illustrations of application-defined knowledge varieties
  3. Convention for representing procedure calls and responses.

For example, if we’ve a requisition to access the Todo application from the Facebook application. Then the Facebook application sends an associated XML request to the Todo application. Todo application analyses the request and generates the XML response and sends it back to the Facebook application.

Advantages of SOAP net service

  • SOAP defines each its format and response
  • SOAP doesn’t compel any restriction on transport. you’ll be able to either use HTTP or MQ (message queue) for communication
  • SOAP uses its own security referred to as WS security.

      Disadvantages of SOAP net service

  • As SOAP uses XML format, so as for the command to be browsed, it ought to be in XML format.
  • SOAP defines several standards that have to be followed while developing the application. Therefore it’s thought-about to be time and resource intensive.
  • Soap is WSDL (net Service Description Language ) dependent, and lacks different mechanisms to find the service.

Web Service Roles

There are 3 major roles among the online service design

Service supplier

This is the supplier of the online service. The service supplier equips the service and makes it accessible on the net.

Service Requestor

Any client of the online Service may be a service requestor. The requestor utilizes associate degree existing net service by gap a network association associate degreed causing an XML request.

Service written record

This is a logically centralized directory of services. The written record provides a standard place wherever developers will publish new services or realize existing ones. It consequently is a centralized financial organization for corporations and their services.

Testing the online Service

After writing the online service in the .net framework, it’s to be sent to processing. Writing net service shoppers is additionally simple within the .NET framework; on the opposite hand, it’s a small amount of concern. One ought to follow bound non-negotiable protocols for a fruitful result.

Security is additionally terribly crucial to net services. However, neither XML-RPC nor SOAP specifications create any express security or authentication necessities.

There are 3 specific security problems with net services −

  • Confidentiality
  • Authentication
  • Network Security
  • Confidentiality

When a sender sends an associate degree XML request to a server, the communication is encrypted via SSL (Secure Sockets Layer) that could be a proven technology and is widely employed in net Services so as to ensure confidentiality.

  • Authentication

The authorization of a consumer is crucial so as to avoid malpractice.

Here’s however the authentication of a consumer is completed whenever the consumer connects to an internet service, though it’s not terribly clear o however sturdy the authentication theme is, it’s somewhat effective

  • HTTP includes intrinsic support for Basic and Digest authentication, and services will therefore be protected equally to however the hypertext mark-up language documents are presently protected.
  • SOAP Digital Signature (SOAP-DSIG) leverages public key cryptography to digitally sign the SOAP messages. It conjointly permits the consumer or server to validate the identity of the opposite party.
  • The Organization for the Advancement of Structured info Standards (OASIS) is functioning on the safety Assertion terminology (SAML).
  • Network Security

Not solely within the net service however this is often a reason behind major issues within the world of laptop networks. There’s presently no simple answer to the present drawback. For now, it’s established that if one really needs to filter out SOAP or XML-RPC messages, one chance is to strain all HTTP POST requests that set their content sort to text/xml.

Another option is to filter the SOAPAction HTTP header characteristic. Additionally to the present, Firewall vendors are presently developing tools unambiguously designed to filter net service traffic.

Now that you are aware of the basics of what a web service is, further there are some commonly asked questions on Web Service in interview, specifically in technical rounds which will help you get an idea of how the questions are framed and how you are supposed to answer. I will mention the most important one’s which are frequently asked web services interview questions before that particular question.

Some generally asked web services interview questions:

1. What is a web service? [basic web services interview questions]

Answer: A web service could be a code that helps in communication between any 2 candidates on the market over the net.

  • A Web Service establishes communication between a consumer and a server over the network using a programmable module with specified formats or protocols.
  • With the help of an associate degree XML electronic communication system, Web Service allows information to be exchanged between two entirely different web applications.

This question is the most asked web services interview questions and also the most confusing one.

2. What’s the distinction between an internet application and an internet service? [basic web services interview questions]

Answer:

Web Services Web Application
A web service is a network-based way of communication between two independent online applications. Web apps are computer programmes or software that execute certain activities using web browsers and web services.
Because it is intended to be a component of a web application, web services do not require a user interface. A web application has a GUI (Graphical user interface)
Web Services are used for Computer processing. Web applications are used by people.
A web service is a set of standard formats or protocols that allow two online apps to exchange information or data. A web application can be created in a number of different languages, including Java, PHP, Python,.NET, and others.

This question again focuses on the application basis of web service, so it’s pretty important to be well versed. This is another Web Services interview questions

3. Why will we use net services? [basic web services interview questions]

Answer: Net services make it easier for two programmes developed in different computer languages to communicate with one another. For commercialism data between apps, they employ the XML standard language. Net services are accustomed to create the applying platform-independent

4. What are the various layers of the protocol stack? [basic web services interview questions]

Answer:

  • Service transport layer
  • XML electronic communication layer
  • Service description layer

5. What’s the performance of the service transport layer of a protocol stack? [basic web services interview questions]

Answer: Exchanging messages between completely distinct apps is the performance of the service transport layer of a protocol stack.

  • HyperText Transport Protocol (HTTP)
  • Simple Mail Transfer Protocol (SMTP)
  • File Transfer Protocol (FTP)
  • Blocks protractible Exchange Protocol (BEEP)

6. What’s the performance of the XML electronic communication layer of the protocol stack? [basic web services interview questions]

Answer: The position of the XML electronic communication layer is to write messages in an exceedingly common format i.e. XML to form it comprehendible to each human activity application. It’s XML-RPC and SOAP protocols.

7. What’s the role of the service description layer of the protocol stack? 

Answer: The service description layer of the protocol stack’s function is to describe the general public interface to a specific net service. It makes use of the Service Description Language (SDL) that is available online (WSDL).

8. What is HTTP? [basic web services interview questions]

Answer: The hypertext transfer protocol (HTTP) is an acronym for hypertext transfer protocol. It allows data to be transferred between the client and the server. Client-server protocol that is simple, stable, and widely disseminated.

Another application based web services interview questions

9. What are the advantages of web api services?

Answer: The following are some of the benefits of using a web API service:

  • Application functionalities that are open through the network.
  • Interoperability
  • Follows a set of guidelines.
  • Efficiency in terms of costs

10.  What is meant by the Interoperability of a web service? [basic web services interview questions]

Answer: Web services allow different apps to communicate and exchange data with one another.

A Python application, for example, can communicate with Java web services and vice versa. As a result, it is platform and technology agnostic.

11.  What is W3C? [basic web services interview questions]

Answer: The World Wide Web Consortium (W3C) is a non-profit organisation that promotes the use of the internet. It’s an international organisation that creates open web service standards.

12. Describe the security of online services in a few words. [ basic web services interview questions]

Answer: The Entrust Secure Transaction Platform ensures the security of web services. To make trustworthy transactions and secure confidential information, web services require a high level of security.

13.  What do you mean by Entrust Privacy Service? [basic web services interview questions]

Answer: Entrust Privacy Service is concerned with privacy and security. This service encrypts data to guarantee that only those who need it have access to it.

14.  What is API? [basic web services interview questions]

Answer: A set of programming commands for accessing a Web-based software application is known as an application-programming interface (API).

This is yet another important Web services interview questions

15. How can APIs be made available to users?

Answer: An “open table” API can be supplied to users. An XML format that points to a web service is known as an open table.

16.  How is RESTful web service different from SOAP web service? [basic web services interview questions]

Answer: Unlike SOAP web services, RESTful web services do not have a contract or WSDL file.

17. What is a SOAP message? What does it include?

Answer: A SOAP message is a document written in XML that provides a standard structure for data transfer between applications.

It contains the following items:

  • Envelope
  • Header
  • Body
  • Fault

18. Is it possible to use a class as a web service? If so, how would you go about doing it?

Answer: Yes, we are able to do so. It’s doable if we inherit the System Web Service class’s properties and qualify the class with the Web Service property.

19. What components must be published during the deployment of a web service?

Answer: The following components are required:

  • Web Application Directory
  • asmx,
  • Web Service.Disco,
  • Config, and
  • Bin directories are all included in the Webservice.asmx file.

20. Mention the client’s actions when accessing a web service? [basic web services interview questions]

Answer: The first step is for the client requesting the web service to create a web service orientation. A proxy class is created after this web orientation. After that, there is a proxy class object, and finally, the client can get a response, i.e. the client can access the web service through the proxy class object.

21. What exactly do you mean when you say “response caching”?

Answer: The smallest number of requests a client makes to a web server is called response caching. It decreases the amount of work that the web server has to do in order to generate a response. Headers that indicate how you want client, proxy, and middleware to cache responses regulate response caching.

22. Is there a drawback to employing response caching?

Answer: Caching entails storing a large amount of data for future use. It expedites the process, but it is impracticable when methods accept a large number of variables.

Another application based most asked web services interview questions

23. Is there any method to deal with caching?

Answer: Yes, Data Caching can be used instead.

24. What exactly is synchronicity?

Answer: Synchronicity refers to the client’s connection to the execution of the service. Before continuing with synchronous invocations, the client blocks and waits for the service to complete its operation.

25.What exactly is JAXP?

Answer: JAXP is a JAVA XML processing API that allows applications to read, write, and manipulate XML data.

26. Name some Java APIs?

  • JAX-RPC
  • JAXM
  • JAXR
  • JAXB
  • JAXP

27. Tell me about the JAXR architecture in a few words.

Answer: A JAXR client and a JAXR provider are both part of the JAXR architecture.

  • Client for JAXR: It’s a client application that makes use of the JAXR API to access a registry via a JAXR provider.
  • Provider of JAXR: It’s a JAXR API implementation that gives you access to a certain registry provider that follows a set of standards.

28. Name the packages available in XML Digital signature API?

  • crypto
  • crypto.dsig
  • crypto.dsig.keyinfo
  • crypto.dsig.spec
  • crypto.dom
  • crypto.dsig.dom

29. What are the types of validation performed by a JAXB client?

Answer: There are two types:

  • Unmarshal Time Validation
  • On-Demand Validation

30. How should you deal with the situation during marshal, unmarshal, and validate operations?

Answer: Register and implement a new event handler using the default event handler

  • Use the ValidationEventCollector tool to collect validation events.

Another very important application based Web services interview questions

31. How is the Network security threat handled in web services?

Answer:

  • By Securing the transport layer and Implementing XML filtering
  • Mask internal resources
  • Validate, Transform, Sign and Timestamp all messages

32. What are the major security issues with web services?

Answer:

  • Confidentiality
  • Authentication
  • Network security

33. What is meant by Marshalling in the java framework? [advanced web services interview questions]

Answer: Marshalling refers to the process of writing Java objects to an XML file.

34. What is meant by Unmarshalling in the java framework? [advanced web services interview questions]

Answer: Unmarshalling is the process of converting XML content to Java objects. 

35. What is Stax? [advanced web services interview questions]

Answer:

  • Stax stands for Streaming API for XML
  • It comes from the JAVA programming language.

36. Describe Push and Pull parsing. [advanced web services interview questions]

  • When a client application needs to interface with an XML document, it uses the Pull Parsing programming model, in which it calls methods on an XML parsing library.
  • The parser that pushes parsing events or XML data to the application is known as Push Parsing. In the push approach, the parser has complete control over the parsing process.

Yet another web services interview questions to be stressed upon

37. What distinguishes Amazon Web Services? [advanced web services interview questions]

  • A cloud computing platform is Amazon Web Services.
  • It offers a wide range of cloud services to its customers.
  • Amazon Web Services (AWS) is a secure cloud service platform that provides database storage, content delivery, and a variety of other features.

This is a pretty important  web services interview questions

38. Name a few Amazon web services? [advanced web services interview questions]

Answer:

  • Amazon Elastic Compute Cloud (EC2)
  • AWS Lambda
  • Amazon SNS
  • Amazon Glacier
  • Amazon CloudFront
  • DynamoDB

39. What are the points that should be considered by ports while binding? [advanced web services interview questions]

Answer: WSDL allows extensibility elements that are used to specify binding information.

40. Explain definition element? [advanced web services interview questions]

Answer: Definition element is described as the root of WSDL document which defines the name of the web service and acts as a container for all the other elements.

These were the top 40 web services interview questions that could help you crack your interview.  Other than this make sure to read up on the background of the company that you are interviewing for, to understand their views and working methods.

More Resources : SQL interview questions for data analyst fresher | Hibernate Interview Questions for freshers | 25 Functional Testing Interview Question and Answers | Basic JUnit Interview Questions and answers

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