Editing SOAP (section)

==Characteristics==
SOAP provides the Messaging Protocol layer of a [[web services protocol stack]] for web services. It is an XML-based protocol consisting of three parts: 
* an envelope, which defines the message structure<ref>
{{cite book
| last1                 = Hirsch
| first1                = Frederick
| last2                 = Kemp
| first2                = John
| last3                 = Ilkka
| first3                = Jani
| title                 = Mobile Web Services: Architecture and Implementation
| url                   = https://books.google.com/books?id=v5f0ORBgd5IC
| publisher             = John Wiley & Sons
| publication-date      = 2007
| page                  = 27 
| isbn                  = 9780470032596
| access-date            = 2014-09-15
| quote                 = Simple Object Access Protocol (SOAP) defines a messaging envelope structure designed to carry application payload in one portion of the envelope (the message body) and control information in another (the message header). 
| date                = 2007-01-11
}}
</ref> and how to process it
* a set of encoding rules for expressing instances of application-defined datatypes
* a convention for representing procedure calls and responses

SOAP has three major characteristics:

#''extensibility'' (security and [[WS-Addressing]] are among the extensions under development)
# ''neutrality'' (SOAP can operate over any protocol such as [[HTTP]], [[SMTP]], [[Transmission Control Protocol|TCP]], [[SOAP-over-UDP|UDP]])
# ''independence'' (SOAP allows for any [[programming model]])

As an example of what SOAP procedures can do, an application can send a SOAP request to a server that has web services enabled—such as a real-estate price database—with the parameters for a search. The server then returns a SOAP response (an XML-formatted document) with the resulting data, e.g., prices, location, features. Since the generated data comes in a standardized machine-parsable format, the requesting application can then integrate it directly.

The SOAP architecture consists of several layers of specifications for:

* message format
* [[Message Exchange Pattern]]s (MEP)
* underlying transport protocol bindings
* message processing models
* protocol extensibility

SOAP evolved as a successor of [[XML-RPC]], though it borrows its transport and interaction neutrality from Web Service Addressing<ref>{{Cite web|url=https://www.w3.org/Submission/ws-addressingCMIS/|title=Web Services Addressing (WS-Addressing)|website=www.w3.org|access-date=2016-09-15|archive-date=2016-09-25|archive-url=https://web.archive.org/web/20160925013438/http://www.w3.org/Submission/ws-addressing/|url-status=live}}</ref> and the envelope/header/body from elsewhere (probably from [[WDDX]]).{{Citation needed|date=August 2011}}