I don't believe that SOAP is tied to any specific protocol. Since it's XML, then it's text-based, which makes http and https convenient protocols. Also, since most Web Services are enabling existing interfaces (likely servlets) you'll already have the facilities to handle http.
It is an understandable impression that SOAP is tied to HTTP because of the current state of development and articles in the technical press. Also the Apache SOAP project has concentrated on RPC over HTTP. However, as David says, it is just an XML text message that can be transmitted any way. Bill
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