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What is Web Service

In this tutorial you will learn

  1. What is web service? 

  2. What is distributed technology? 

  3. Types of distributed technology 

  4. Advantages of web service. 

  5. Remote 

What is web service?

Web services are not a direct software/ technology to install and use. Working with web services is all about working with multiple technologies, concepts, specifications and protocols together to develop distributed applications. Web services is a way to create language independent (at max and not 100%), OS independent, Architecture independent communication between applications which are geographically dispersed and running in different machines.

What is distributed technology?

A technology is said to be distributed if it's business objects are geographically dispersed (across multiple JVM's) and still communicating one another.

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Achieving the same performance irrespective of increase or decrease in number of clients/requests is nothing but developing scalable application.

Distributed application can be developed as scalable application.

To develop distributed application, we need distributed technology.

Different distributed technologies:

1.  RPC(Remote Procedure call)

2.  RMI(Remote Method Invocation)

3.  CORBA

4.  DCOM (Distributed Component Object Model)

5.  EJB

6.  Web Services (SOAP, REST)

7.  HttpInvoker

Web Services, HttpInvoker gives web based distributed application (Http Protocol) whereas the remaining distributed technologies allow to develop non-web based distributed application.

Advantages of web services (SOAP, REST)

  • Language independent (at max and not 100%) 

  • OS independent 

  • Architecture independent. 

  • Allows to convert existing business component  into web services not only to develop scratch level distributed applications, we can also use them to convert existing business components to interoperable business components. While working with hardware components, we never bother about their compatibility with other devices and components because they are developed as interoperable components. The ability to work with components/resources without worrying about their environment is nothing but interoperability. 

  • In web services based distributed application the server application can be developed in any language and the client application can be developed in any language. 

  • Given based on SOA (Service Oriented Architecture) specification. SOA is a software dosing principle having idea, plan to develop interoperable distributed application. SOA specifies the requirement and benefits of developing interoperable distributed applications. 

  • Web services is not given by any specification organization. 

Remote Interface

In distributed applications, the business component/business object must be developed as Remote object. The object whose methods can be invoked from both remote and local cients is called as remote object. Java object becomes remote object only when it implements the marker interface called java.rmi.Remote

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