Thanks for the suggestion - I spent a couple of hours reading the SOAP docs, and am obviously a SOAP newbie - any thoughts on advantages over an Apache2/mod_perl despatch?

There are the obvious ones of standardisation of arg formatting and presentation, and future-proofing for various callers to the app server, but for our requirements, small sets of name=value args are all that is required, and these are easily generated in the PHP web front-end. Are there any others you have experienced / like?