SOAP vs other protocols

SOAP (Simple Object Access Protocol) is an XML-based protocol that allows objects of any kind (Java, COM, etc.) on any platform and in any language to communicate. SOAP follows a RPC-style request/response mechanism. Data can be serialised without regard to any specific transport protocol, although HTTP is typically the protocol of choice.

RMI, SOAP's chief competitor, is the process of activating a method on a remotely running object. Java RMI provides a mechanism for supporting distributed computing.
In RMI, a remote method is invoked directly through a remote object's stub.The invocation and results are encoded across the network. The biggest advantage here is:

• type-safety - the direct use of method names is possible and compile-time errors occur if arguments are incorrect

Conversely, an RPC-style call (eg: SOAP) sends a request message to the remote server, which formulates the response and sends it back. The client does not invoke a method directly. The main advantage of the RPC style is:

• greater independence between client and server