What’s Web Service?


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1/ What are Web services?

A Web Service is can be defined by following ways:

  • is a client server application or application component for communication.
  • method of communication between two devices over network.
  • is a software system for interoperable machine to machine communication.
  • is a collection of standards or protocols for exchanging information between two devices or application.

Let’s understand it by the figure given below:


As you see the figure, java, .net or PHP applications can communicate with other applications through web service over the network.

(Refer from http://www.javatpoint.com/what-is-web-service)

2/ Components of Web Services

The basic web services platform is XML + HTTP. All the standard web services work using the following components:

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

3/ How does a Web service work?

A web service enables communication among various applications by using open standards such as HTML, XML, WSDL and SOAP. A web service takes the help of:

  • XML to tag the data
  • SOAP to transfer a message
  • WSDL to describe the availability of service.

You can build a Java-based web service on Solaris that is accessible from your Visual Basic program that runs on Windows.

You can also use C# to build new web services on Windows that can be invoked from your web application that is based on Java Server Pages (JSP) and runs on Linux

4/ Example

Consider a simple account-management and order processing system. The accounting personnel use a client application built with Visual Basic or JSP to create new accounts and enter new customer orders.

The processing logic for this system is written in Java and resides on a Solaris machine, which also interacts with a database to store information.

The steps to perform this operation are as follows:

  • The client program bundles the account registration information into a SOAP message.
  • This SOAP message is sent to the web service as the body of an HTTP POST request.
  • The web service unpacks the SOAP request and converts it into a command that the application can understand.
  • The application processes the information as required and responds with a new unique account number for that customer.
  • Next, the web service packages the response into another SOAP message, which it sends back to the client program in response to its HTTP request.
  • The client program unpacks the SOAP message to obtain the results of the account registration process.

(Refer from https://www.tutorialspoint.com/webservices/what_are_web_services.htm)

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