A platform-independent formatted protocol based on extensible markup language XML enabling applications to communicate with each other over the Internet(Use of SOAP may provide a significant security risk to web application operations because use of SOAP piggybacks onto a web-based document object model and is transmitted via HyperText Transfer Protocol (HTTP) (port 80) to penetrate server firewalls, which are usually configured to accept port 80 and port 21 File Transfer Protocol (FTP) requests. Web-based document models define how objects on a web page are associated with each other and how they can be manipulated while being sent from a server to a client browser. SOAP typically relies on XML for presentation formatting and also adds appropriate HTTP-based headers to send it. SOAP forms the foundation layer of the web services stack, providing a basic messaging framework on which more abstract layers can build. There are several different types of messaging patterns in SOAP, but by far the most common is the Remote Procedure Call (RPC) pattern, in which one network node (the client) sends a request message to another node (the server), and the server immediately sends a response message to the client)
Simple Object Access Protocol A simple, XML-based protocol for exchanging structured data and type information on the World Wide Web. The protocol is currently the de facto standard for XML messaging
