Introduction To Web Services (CSE Department @ LAQSHYA College)

Introduction To Web Services

A web service is a collection of open protocols and standards used for exchanging data between applications or systems. Software applications written in various programming languages and running on various platforms can use web services to exchange data over computer networks like the Internet in a manner similar to inter-process communication on a single computer. This interoperability (e.g., between Java and Python, or Windows and Linux applications) is due to the use of open standards.

Web services are XML-based information exchange systems that use the Internet for direct application-to-application interaction. These systems can include programs, objects, messages, or documents.
Interoperability has Highest Priority

“Any thing that is accessible irrespective of programming language and platform.”

Components of Web Services

The basic Web services platform is XML + HTTP. All the standard Web Services works using following

components

1.       SOAP (Simple Object Access Protocol)

2.       UDDI (Universal Description, Discovery and Integration)

3.       WSDL (Web Services Description Language)

1. SOAP

S SOAP provides a way to communicate between applications running on different operating systems, with different technologies and programming languages.

Skeleton SOAP Message

<?xml version="1.0"?>
<soap:Envelope
xmlns:soap="http://www.w3.org/2001/12/soap-envelope"
soap:encodingStyle="http://www.w3.org/2001/12/soap-encoding">
<soap:Header>
...

</soap:Header>
<soap:Body>
...
  <soap:Fault>
  ...
  </soap:Fault>
</soap:Body>

2. UDDI:

 Universal Description, Discovery and Integration (UDDI) is a directory service where businesses can register and search for Web services. It can store all the WSDL documents in it. Provider will publishes the WSDL documents to the UDDI registry and consumers will browse for a WSDL document form the registry.

WSDL

3.   WSDL

Stands for Web Services Description Language

WSDL is often used in combination with SOAP and XML Schema to provide web services over the Internet.

The main structure of a WSDL document looks like this:

<definitions> … It defines the name of the web service. <types>    definition of types........ the data types that are used by the web service. </types> <message>    definition of a message.... data elements of an operation. </message> <portType> It describes a web service, the operations that can be performed, and the messages that are involved.       <operation>                   definition of a operation.......        </operation> </portType> <binding>    definition of a binding.... data format and protocol for each port type. </binding> <service>    definition of a service....</service></definitions> --------------------------------------------------------------------------------- Article By -------------- R.Rupa                      Assistant Professor CSE Department LAQSHYA Institute of Technology & Sciences