What's the difference between XML-RPC and SOAP?

The xml-rpc spec fits on 1 page 6 pages. The SOAP 1.2 spec will cost you a 500 page ream 44 pages. SOAP is more powerful, and is much preferred by software tool vendors (MSFT .

NET, Java Enterprise edition, that sort of things). SOAP was for a long time (2001-2007ish) seen as the protocol of choice for SOA. Xml-rpc not so much.

REST is the new SOA darling, although it's not a protocol. SOAP is more verbose, but more capable. SOAP is not supported in some of the older stuff.

For example, no SOAP libs for classic ASP (that I could find). SOAP is not well supported in python. XML-RPC has great support in python, in the standard library.

SOAP supports document-level transfer, whereas xml-rpc is more about values transfer, although it can transfer structures such as structs, lists, etc. Xm-rpc is really about program to program language agnostic transfer.It primarily goes over http/https. SOAP messages can go over email as well. Xml-rpc is more unixy.It lets you do things simply, and when you know what you're doing, it's very fast to deploy quality web services, even when using terminal text editors.

Doing SOAP that way is a zoo; you really need a good IDE to make it feasible. Knowing SOAP, though, will look much better on your resume/CV if you're vying for a Fortune 500 IT job. Xml-rpc has some issues with non-ascii character sets.

Edited: Just wanted to add that XML-RPC does not support named parameters. They must be in correct order. Not sure about SOAP, but think so.

1 For SOAP with Python, there is the ZSI package. It is quite good, but you absolutely need a wsdl. – edomaur Oct 18 '08 at 7:34 I believe the old SOAP Toolkit had support for "Classic ASP".

More to the point, one can use your favorite . NET language to create a COM component that wraps a Service Reference, allowing Classic ASP to consume even a modern web service. – John Saunders Feb 21 at 4:42 @Mark Harrison and Christopher: What do you mean "Doing SOAP that way is a zoo".

Sorry, I could not able to understand the word "zoo". Please describe it... – Saravanan Feb 22 at 4:06 A zoo, as an american expression, is like a real zoo: a very confusing place. – Christopher Mahan Feb 22 at 16:46.

Just to add to the other answers, I would encourage you to look at actual textual representations of SOAP and XML-RPC calls, perhaps by capturing one with Ethereal. The whole, "XML-RPC is simpler" argument doesn't make much sense until you see how incredibly verbose a SOAP call is. Many of the fairly popular web sites out there shy away from SOAP as their API due to just the amount of bandwidth it would consume if people started using it extensively.

This page, though dated, has some useful information: weblog.masukomi.org/writings/xml-rpc_vs_... Long story short: XML-RPC is simpler to learn and use, but SOAP is more powerful.

– Rob Cooper Sep 17 '08 at 5:01 Well, if the links are informative... – Josh Matthews Sep 17 '08 at 5:24 Well, StackOverflow should be the resource they come to, even if you link and excerpt it is a lot more useful than pasting a link. If you want links, go to Google. Here we want answers.

– Rob Cooper Sep 17 '08 at 5:50 3 Rob, if someone already has a good answer on the web, how do you propose it gets on to stackoverflow? Should the author write it out again word for word to save you the bother of clicking a link? If the link is no good then vote the answer down.

– Justicle Sep 17 '08 at 0:54 Note that I did give an answer, though one that summarizes the content of the link. The full answer would be several screens long. – Thomas Sep 17 '08 at 10:51.

SOAP allows any XML elements to be sent through, XML-RPC is limited to a predefined number of parameters and is limited in what types they can be.

Kate Rhodes has a great essay on the differences at weblog.masukomi.org/writings/xml-rpc_vs_....

I am not sure of the major differences between the two, all I know is that both came out of Redmond & Dave Winer, and SOAP is the newer, preferable option. AFAIK I think SOAP basically has more header information and attributes, allowing better (more robust) transport of data types - I could be wrong though.

1: Came out of Redmond is BS. – John Saunders Feb 21 at 4:42 1 -1: that's a really blabla statement - especially for someone who seems to criticise everyone else for their answers – ssc Sep 7 at 8:21.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.