SOAP stands for Simple Object Access Protocol.SOAP is a protocol for accessing web services.SOAP is based on XML.

What is SOAP?

  • SOAP is a communication protocol
  • SOAP is for communication between applications
  • SOAP is a format for sending messages
  • SOAP communicates via Internet
  • SOAP is platform independent
  • SOAP is language independent
  • SOAP is based on XML
  • SOAP is simple and extensible

SOAP allows you to get around firewalls

 

Why SOAP?

It is important for application development to allow Internet communication between programs.

Today’s applications communicate using Remote Procedure Calls (RPC) between objects like DCOM and CORBA, but HTTP was not designed for this. RPC represents a compatibility and security problem; firewalls and proxy servers will normally block this kind of traffic.

A better way to communicate between applications is over HTTP, because HTTP is supported by all Internet browsers and servers. SOAP was created to accomplish this.

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

SOAP Building Blocks

A SOAP message is an ordinary XML document containing the following elements:

  • An Envelope element that identifies the XML document as a SOAP message
  • A Header element that contains header information
  • A Body element that contains call and response information
  • A Fault element containing errors and status information

All the elements above are declared in the default namespace for the SOAP envelope:

Syntax Rules

Here are some important syntax rules:

  • A SOAP message MUST be encoded using XML
  • A SOAP message MUST use the SOAP Envelope namespace
  • A SOAP message MUST use the SOAP Encoding namespace
  • A SOAP message must NOT contain a DTD reference

A SOAP message must NOT contain XML Processing Instructions.

EXAMPLE:


<?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>
</soap:Envelope>

By Prashansa Kumari

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