WEBSERVICE – XML & SOAP

The XML and SOAP are used in building web service component for the web applications. Before start using XML and SOAP in web service, we should know what is web service and where it should be used in web applications.

What is Web Service?

A web service is a collection of 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.

Web Services didn't just exist suddenly. They aren't a new revolution; rather they have to be seen as an evolution based on existing Internet protocols. They are the logical next step. Since 1994, Distributed Objects have been developed by several organizations under various names. NeXT called them Portable Distributed Objects, Microsoft called them Component Object Model (COM), IBM called them System Object Model (SOM), and Apple called them OpenDoc. These companies (with the exception of Microsoft) formed the Object Management Group (OMG) and converged upon a standard called Common Object Request Broker Architecture (CORBA). The concept was to develop an architecture that lets applications plug in to an "application bus" and call a service. Based on object-oriented units, it called on specialized software components. Today, interoperable objects are being called Web Services.


The Web Services protocol stack consists of three key XML-based technologies: SOAP (Simple Object Access Protocol), WSDL (Web Service Description Language), and UDDI (Universal Description, Discovery and Integration).

UDDI: This layer is responsible for centralizing services into a common registry, and providing easy publish/find functionality. Currently, service discovery is handled via the UDDI. The UDDI specification can help to solve making it possible to discover the right services from the millions currently online. Learn more about UDDI here.

WSDL: This layer is responsible for describing the public interface to a specific Web service, which is an XML-based language that describes the various functions that a Web service is capable of. Currently, service description is handled via the WSDL. You do not need to learn all the nitty-gritty details because there are tools that generate WSDL for you. You can get one here.

SOAP: This layer is responsible for encoding messages in a common XML format so that messages can be understood at either end. Currently, this includes XML-RPC and SOAP. For example, the client program bundles up two values (see Figure 1) to be added into a SOAP message, which is sent to the Web service by sending it as the body of an HTTP POST request. The server unpacks the SOAP request that the application can understand and executes Add operation. Next, the server packages up that result of summation as 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 summation. So, SOAP=XML + HTTP.


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Karpagarajan. R
Necessity is the mother of invention

Web Service is a software component for application to application communication.

Web services use XML based communicating protocols.

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S.VinothkumaR
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Before me is Endless Possibility,
Around me is Boundless Opportunity,
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