How to create a web service that receives sends xml with nusoap?

I need to create a .php web service that accepts xml, uses this to query a database, and then returns the response. I how i can capture the file xml?

oHTTP = CREATEOBJECT('Msxml2.ServerXMLHTTP.6.0')
oHTTP.OPEN("POST", &p_urlws , .f.)
pFileRequest='REQUEST WRITTEN IN XML'
oHTTP.setRequestHeader("Content-Type", "text/xml;charset=utf-8")
oHTTP.setRequestHeader("SOAPAction", "http://etc....")
oHTTP.SEND(pFileRequest)
p_StatusWS = oHTTP.STATUS
RespuestaWS = oHTTP.responseText

p_urlws="'http://ift.tt/28MSUaJ'"

I need to read the REQUEST WRITTEN IN XML...!