Top Most What is SOAP?

SOAP is an XML-based protocol for exchanging information between computers. Although SOAP can be used in a variety of messaging systems and can be delivered via a variety of transport protocols, the main focus of SOAP is Remote Procedure Calls (RPC) transported via HTTP. Like XML-RPC, SOAP is platform independent, and therefore enables diverse applications to communicate with one another.

To get a quick sense of SOAP, here is a sample SOAP request to a weather service (with the HTTP Headers omitted): 

< ?xml version='1.0' encoding='UTF-8'?> 
< SOAP-ENV:Envelope xmlns:SOAP-ENV="http://www.w3.org/2001/09/soap-envelope" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xmlns:xsd="http://www.w3.org/2001/XMLSchema"> 
< SOAP-ENV:Body> 
< ns1:getWeather xmlns:ns1="urn:examples:weatherservice"
SOAP-ENV:encodingStyle=" http://www.w3.org/2001/09/soap-encoding
< zipcode xsi:type="xsd:string"> 10016< /zipcode> 
< /ns1:getWeather> 
< /SOAP-ENV:Body> 
< /SOAP-ENV:Envelope> 
As you can see, the request is slightly more complicated than XML-RPC and makes use of both XML namespaces and XML Schemas. Much like XML-RPC, however, the body of the request specifies both a method name (getWeather), and a list of parameters (zipcode).

Here is a sample SOAP response from the weather service:

< ?xml version='1.0' encoding='UTF-8'?> 
< SOAP-ENV:Envelope xmlns:SOAP-ENV="http://www.w3.org/2001/09/soap-envelope"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"> 
< SOAP-ENV:Body> 
< ns1:getWeatherResponse xmlns:ns1="urn:examples:weatherservice"
SOAP-ENV:encodingStyle="http://www.w3.org/2001/09/soap-encoding"> 
< return xsi:type="xsd:int"> 65< /return> 
< /ns1:getWeatherResponse> 
< /SOAP-ENV:Body> 
< /SOAP-ENV:Envelope> 
The response indicates a single integer return value (the current temperature). 
The World Wide Web Consortium (W3C) is in the process of creating a SOAP standard. The latest working draft is designated as SOAP 1.2, and the specification is now broken into two parts. Part 1 describes the SOAP messaging framework and envelope specification. Part 2 describes the SOAP encoding rules, the SOAP-RPC convention, and HTTP binding details