This seems unusual, though not out of the question. This means that the web server must have network access to the file. Will that be the case? If so, you can probably do a “get” operation and pass data/args to pass the filename using the variable name that the web server expects.
Again, you probably need to get additional info from the web server people to ensure you’re posting things the right way.
A part of me is thinking you may be trying to leverage a file input facility that is supported by browsers using the “file” input field type. Is that the case? If so, then you’ve got a bit more work to do, such as creating a multipart/form-data document to be submitted.
#Integration-Server-and-ESB#webmethods-Protocol-and-Transport#webMethods