a> The 503 Error is not caused by running it in a browser, you should see a blank page.
Are you sure it is a 503? not a 500? 503 should have nothing to do with php at all that is a server problem.
Normally a 500 is still a server problem, i.e a module not loading, htaccess wrong, etc etc etc.
b> If you really want to do testing check out
http://www.soapui.org/
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