webmethods XI integration

The wMethods user guide for XI adapter tells me the Adapter provide an URL to which XI can post the XML message over HTTP.Now the question I have is

If its an Outbound from XI scenario

SAP-> XI → wM-> 3rd Party.

I have configured the wM-XI adapter instance in wM server, do i need a HTTP Receiver adapter Channel in SAP XI configured to post the XI msg to the wM-XI Adapter Instance on wMethods IS??..

But as I understand the wM adapter runtime is already registered with SLD and is available to SAP XI Runtimeworkbench, shdn’t I still do well with a native HTTP communication between the Inbound Interface and HTTP adapter Channel in wMethods end…

Or do i have a

SAPXI HTTP Receiver → Post to → wM - XI adapter URL(as a receiver)->wM Service

HOW DOES IT WORK!!! Thought shd ask the learned one’s in the forum before taking it with wMethods…