|Type||Light Weight||Easy to build||Rigid||Examples|
|REST||Yes(no extra xml markup)||Yes||No||Yahoo Services(Flickr,Technorati)|
|SOAP||No(soap specific xml markups)||No(Requires tools eg. apache axis2)||Yes(Support for Type Checking, WSDL)|
(Apache XML RPC library can be used)
(has a predefined xml envelop for invoking methods with params, data types are supported)
What is REST?
The acronym REST stands for Representational State Transfer. This means that each unique URL is a representation of some object. You can get the contents of that object using an HTTP GET, to delete/update it, you then might use a POST, PUT, or DELETE.
What is SOAP?
SOAP is a protocol for accessing a web-service. More information here.
What is XML/RPC?
XML-RPC is a remote procedure call protocol which uses XML to encode its calls and HTTP as a transport mechanism. It is primarily designed to call methods. See this link for an example.