In thread http://moodle.org/mod/forum/discuss.php?d=200117 I looked into the idea of creating a kind of proxy service running on Glassfish which acts as an go between between clients and Moodle webservices running on each individual Moodle server.
I've tested this locally and it works, although tested only one call so far, more operations to add.
Basically the proxy server can call your own Moodle server webservices via REST protocols which has been sent the URL, credentials, webservice function and parameters from a client which has generated its interface to the proxy server via WSDL. The WSDL generated is compliant so a range of programming languages can in effect easily call Moodle webservices in a round about way on your own server for you.
I would need to modify the Java REST library a bit as it currently uses static methods and there might be some crosstalk between threads on the proxy server, initially the library was writen to integrate systems within a single site so was not a problem.
I will probably need to use C# or C/C++ to communicate back to our MIS(SIMS) so will probably go down this route anyway and I don't want to create new libraries for these languages.
With the absence of a fully WSDL compliant service within Moodle, what do you think?