Scripts that deal with such complex standards as SOAP and/or XML-RPC would be difficult as that takes a lot of reading to be able to code a compatible script. Will (Bluesaga on TP) has been doing a PCNTL wrapper recently which because of its apparent lack of a decent documentation, was apparently quite difficult to master.

On that note, I'm going to have say that creating an API (not conversing with an API) would be quite a difficult script. Not a simple API that provides the data into XML documents, but one that offers the full-works, that is all the PHP classes to communicate with the server, and a full API documentation on how to do certain tasks.

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