Something to look at & consider:
XML-RPC
I haven't messed with it much, but for what you may possibly be doing, with the distributed stuff, this may be a good option. You don't have to parse the XML, technically, since the XML-RPC libraries will pull the data from the XML & put it into data structures (arrays, strings, etc). On their site, they have
implementations listed using many different languages (c++, java, perl, php, etc)
And, general XML help:
W3 Schools