How to call a wsgi app from a php file- using curl, 'post' method. XML data is to be sent as post body and a webhook too has to be supplied.

Question

I have a WSGI app which accepts data sent to it by the 'POST' method. It requires xml data with content-type parameter set to 'application/xml', a valid content-length parameter and a webhook parameter. I have to call this WSGI app by a php file, preferably using a cURL command. How exactly can i do it? Moreover, the webhook file will be another php- what can its contents be so that I can use it for testing purposes to know that it has actually been called by the WSGI app? I have tried to many things, but something almost always goes wrong.