SOAP is an XML-based protocol to let applications exchange information over HTTP.
Or more simple: SOAP is a protocol for accessing a Web Service.
- SOAP stands for Simple Object Access Protocol
- SOAP is a communication protocol
- SOAP is a format for sending messages
- SOAP is designed to communicate 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
- SOAP is a W3C standard
Although SOAP can be used in a variety of messaging systems and can be delivered via a variety of transport protocols, the initial focus of SOAP is remote procedure calls transported via HTTP.
SOAP enables client applications to easily connect to remote services and invoke remote methods.
Other frameworks, including CORBA, DCOM, and Java RMI, provide similar functionality to SOAP, but SOAP messages are written entirely in XML and are therefore uniquely platform- and language-independent.
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 was designed as an object-access protocol in 1998 by Dave Winer, Don Box, Bob Atkinson, and Mohsen Al-Ghosein for Microsoft, where Atkinson and Al-Ghosein were working at the time. The SOAP specification is currently maintained by the XML Protocol Working Group of the World Wide Web Consortium.
SOAP originally stood for ‘Simple Object Access Protocol’ but this acronym was dropped with Version 1.2 of the standard. Version 1.2 became a W3C recommendation on June 24, 2003. The acronym is sometimes confused with SOA, which stands for Service-oriented architecture, but the acronyms are unrelated.
After SOAP was first introduced, it became the underlying layer of a more complex set of Web Services, based on Web Services Description Language (WSDL) and Universal Description Discovery and Integration (UDDI). These services, especially UDDI, have proved to be of far less interest, but an appreciation of them gives a more complete understanding of the expected role of SOAP compared to how web services have actually evolved.
Contents of SOAP–
What is SOAP ?
This chapter explains what is SOAP and why SOAP is useful.
SOAP Message Structure
This chapter describes the structure of a complete SOAP message.
This chapter describes the SOAP Envelope element of SOAP message.
This chapter describes the SOAP Header element of SOAP message.
This chapter describes the SOAP Body element of SOAP message.
This chapter describes the SOAP Fault element of SOAP message.
This chapter describes the built-in set of rules for encoding various data types.
This chapter describes the transport protocols for SOAP to exchange the messages.
This chapter has given a simple SOAP example to illustrate the concepts.
This chapter gives links to latest standards related to SOAP.
1. Wikipedia for SOAP