What’s the best way to integrate with a SOAP protocol HTTP service?
Hitting the endpoint must happen ad-hoc and invoking the service during data transformations is not an option.
You can use the REST API source type with webhooks to make SOAP requests over HTTP. Perhaps the REST API source should actually be called the “HTTPS source” since that’s what it actually offers 
We recently added support for XML body types (as well as a few others - plain text, HTML, and binary attachments) which should make it much easier to construct the SOAP request body that you wish to send as part of the request.
