Simple Object Access Protocol (SOAP) is a protocol that allows communication between various systems. It describes a standard way to create messages that can be sent from one system to another. SOAP defines the format of a message so that there is a standard place for various parts of the message such as the envelope and the body. Establishing standards such as the location and characteristics of these message parts allows quicker integration since all the systems involved in the communication use the same protocol. In a SOAP communication, in addition to a standard message format, the message body itself is an XML document. This allows for the integration of disparate systems, since any system that can process text (XML) can understand the protocol.
SOAP was born out of a need for XML RPC (Remote Procedure Call). There are two different parts to any SOAP interaction: the client and the server.
The SOAP client:
generates a SOAP envelope.
places the payload, or content, into it.
designates a particular service on the destination server to which the message should be delivered.
sends the message over HTTP to the destination server.
The server:
maintains a registry that maps service names to actual locations of services.
receives messages and examines them to determine to which service they should be delivered.
looks in its mapping table for the service name.
delivers the message’s content to the associated method in the mapped service.
