XML-RPC vs JAX-RPC

XML-RPC

XML-RPC is a remote procedure call protocol which uses XML to encode its calls and HTTP as a transport mechanism. XML-RPC is a very simple protocol, defining only a handful of data types and commands, and the entire description can be printed on two pages of paper. Some people still prefer XML-RPC to SOAP because of its simplicity, minimalism, and ease of use. (source wikipedia)

The original XML-RPC uses only a few data types and does not require namespaces. It achieves considerable flexibility by defining and types which can contain other values. Responses are also simple XML with as the root element with either or as the child element. The contrast with complex SOAP responses is striking.

For xml-rpc, wsdl and uddi is not involved for client to invoke the web service.

Implementations of XML-RPC:

There are five Implementations in Java list at xmlrpc.com as of December 2003. However, many of these projects appear to be inactive. The project hosted by the Apache Web Services Project is active. It looks like the Apache Web Services Project is on the right track with version 3, so keep an eye open on it if you are interested in an open-source XML-RPC solution.

JAX-RPC - The Java API for XML-based RPC

Instead of using xml-rpc protocol, JAX-RPC make used of SOAP protocol for messaging which enable web service a industry standard.

SOAP

SOAP is a protocol for exchanging XML-based messages over computer networks,normally using HTTP/HTTPS. SOAP forms the foundation layer of the Web services stack, providing a basic messaging framework so that more abstract layers can build on.

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. SOAP is the successor of XML-RPC, though it borrows its transport and interaction neutrality and the envelope/header/body from elsewhere, probably from WDDX. (Source: wikipedia)

WSDL is involved for client to invoke the web service when use JAX-RPC.

Is XML-RPC Still Useful?

The complexity of the JAX-RPC implementation has caused somewhat of a backlash among programmers. It seems you should consider XML-RPC over JAX-RPC if:

* Your application uses relatively simple requests
* You control both server and client sides and/or you don't need to publish a WSDL
* You want to keep client-side parsing simple (as in AJAX applications)