Web Services Interview Questions


What are Web Services ?

A standardized distributed communication system that interchange data between applications over an internet. In other words, it is connection technology that allows a system to communicate with different applications.Traditional system was working on client-server model technique but web services share data through an interface across the network. Web services use XML, SOAP, WSDL and UDDI open standards for exchange information.

Web Services Components: -

  • UDDI: - Universal Description, Discovery, and Integration. (Used for listing available services)
  • SOAP: - Simple Object Access Protocol (Used to transfer data)
  • WSDL: - Web Services Description Language (Used to describe services)


The primary element of Web Services: -

  • Messaging
  • Services
  • Repository

Web services allow communication between different types of application in less time without adding extra functionality. Web services provide a web-based user interface that consumes data from different machines and servers and bind it into one interface.

How it works: - We can easily understand working algorithm of web services.

  • A client machine binds some information in a SOAP message.
  • Client machine sent SOAP message to web services with HTTP request.
  • After that web services, open SOAP message and convert these messages into such type of command that a machine can understand.
  • Now server process information as required and send it to web services.
  • Web services bind this information in a new SOAP package and send back to client machine to its HTTP request.
  • Now client machine unpacks the SOAP message and collects info as required.


Over the network there are different types of web services are used like Java, PHP, SOAP, REST, JSON and many more.

  • SOAP (Simple Object Access Protocol): - SOAP is platform independent protocol for information exchange. It interchanges data in-between two systems. It is based on XML language, easy to understand by machine. In simple word, SOAP plays a vital part in data exchange. It manage data, communicates with internet, and send packages to web services, again receive a package, unpack, and convert it to machine language.A SOAP message contains following element: -
  • SOAP – Envelope: - Contain header and footer of message.
  • SOAP – Header: - Used to process message
  • SOAP – Body: - Contain data in XML format
  • SOAP – Fault: - Show errors


SOAP uses different transfer protocol like HTTP, SMTP to transfer message. SOAP can be slow sometimes as compare to some middleware technologies because of XML language.

  • REST (Representational State Transfer): - Describe a set of rules that transfer data over an HTTP interface. REST is more usable by developers because its structured style makes it easy than SOAP. It doesn’t contain an extra layer and provides stateless services. Rest is used to build lightweight, flexible web services. A service that is built on REST architecture called RESTful service. REST is a structural style, not a protocol.Some Key element of RESTful service: -
  • Resource: - Information that stored on Server.
  • Resource Identifier: - Identify resources.
  • Representation: - Data in XML or HTML format.
  • Request Verbs: - RESTful services use GET, PUT, DELETE, POST like verbs.
  • Request Header: - Contain extra authorization instruction.
  • Request Body: - Include resource details.
  • Response Body: - Contain information sent by server to client.
  • Response Status Code: - HTTP response code (like 200, 301,302).

Advantages of RESTful services: -

  • RESTful services are fast as compared to SOAP.
  • It is not language dependent like SOAP.
  • It can use SOAP services.
  • It allows data in different format like XML, HTML, JSON etc.
  • Send resources with unique URI.
  • RESTful architecture is stateless and based on client/server, it also supports caching.

RESTful web service comes with more scalability and provide secure transmission to various application, which is built on different programming languages and platform.

  • JSON (JavaScript Object Notation): - JSON uses a part of JavaScript to exchange while other services use XML format for interchange data. JSON used HTTP POST Request and Response method for communication. In JSON CICS is responsible for transforming incoming JSON data into application data.
  • Java Web Services: - There are two type of JWS concept
  • JAX-WS
  • JAX-RS

Java Web Services can also be accessed by other programming languages like .Net, PHP. Java Web Services communicate through WSDL (Web Services Description Language).

There are two ways to write JAX-WS application code

  • RPC Style: - This style use parameter and method name to generate XML architecture and generated file are difficult to validate.
  • Document Style: - In this style, parameter is sent in XML format and validated in a predefined schema.

In JAX-RS, there are two approaches to write a code

  • Jersay
  • RESTeasy
  • Web Services Description Language (WSDL): - A XML based protocol for information exchange. A service consumer uses the WSDL to send a request.


Conclusion:
- Web Services have become backbone of modern communication system. Common protocols and interfaces used to develop mobile, table and PC application with security.

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Some of the many Web Services Interview Questions listed below will help you get an idea about what questions gets asked in such jobs related to Software Engineering & Tech. Get through the Web Services Interview bar with our selected Web Services Interview Questions for all Web Services enthusiasts!


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