need to construct a XML file and do HTTP POST to webservice URL--Blackberry

I need 开发者_StackOverflow中文版to construct a xml like this

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:wsu="http://docs.xyz/2009/01.xsd" xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/" xmlns:tns="http://service.xyz.com/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" >
<SOAP-ENV:Body><mns1:getVisitList xmlns:mns1="http://service.xyz.com/">
<input_no>321</input_no>
</mns1:getvisitlist>
</SOAP-ENV:Body>
</SOAP-ENV:Envelope>

and i want to do http post this to a webservice url to get some json output response.. i dono where to start.. can anyone help me with this ?? any idea please..