Introduction to SOAP

SOAP stands for Simple Object Access Protocol, an XML-based protocol that allows a program running in one operating system to communicate with another program in another operating system over the internet. It was developed by a group of vendors, including Microsoft, to revolutionize how web applications are developed. The SOAP standard is not just an XML standard. The standard includes how SOAP messages should behave, the different transports used, how errors get handled, and more.

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With distributed computing and web applications, a request for an application comes from one computer the Client and is transmitted over the Internet to another computer the Server. There are many ways of doing this, but SOAP makes it easy by using XML and HTTP.

SOAP Features

  • Uses standard internet HTTP
  • A protocol for exchanging information in a decentralized and distributed environment
  • Uses XML to send and receive messages
  • Platform independent
  • Language independent

Simple SOAP Message Format

<?xml version=" "?>
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">

<soap:Header>

</soap:Header>

<soap:Body>

<-- Fault element is optional,
used only if a fault occurs in web service.
-->
<soap:Fault>
</soap:Fault>

</soap:Body>

</soap:Envelope>

SOAP Elements

  • Envelope
  • Header
  • Body
  • Fault

SOAP message consists of a Envelope element, inside which a Header and a Body element can be nested. Inside the Body element a Fault element can be nested, if an error occurs in the web service.

Where is SOAP Used

One of the most important uses of SOAP is to help enable XML Web Services. A web Service is an application provided as a service on the web. They are functional software components that can be accessed over the Internet. Web Services combines the best of component-based development and are based on

Internet Standards that supports communication over the net. SOAP is fueling the rapid rise of Web services, which have the potential to change the face of Internet application development. Web services are Internet-based modules that perform a specific business task.

Limitations of SOAP

  • SOAP is a simple protocol, As the name suggests it’s a simple protocol and works on HTTP, we cannot expect all the functionality offered by other protocols.
  • SOAP may turn out to be slower compared to other proprietary protocols as it requires additional XML processing.
  • Still SOAP fares well in most areas compared to other wire protocol. As per the specifications, SOAP can also use other transport carrier to transmit SOAP messages.

In Closing

This is the reasonably understandable description of SOAP. If you have any good tips on SOAP, or any questions, just pop a comment below.