Pass parameters to a SOAP Service

I can't figure out how to pass parameters coming from a form to a web service. I suppose i have to use an XPATH expression but i don't know how and where.

Is there somebod开发者_如何学Pythony here that knows how to do that ?

In advance thank you,

See this how-to: Call a service passing a field value. It will walk you though the process of creating a form which uses the Yahoo! Weather API to give you weather information about a city you select, calling the service every time you change the value, and showing the result in another field.