I need to retrieve files from my customers using http. I can logon the site and get to the download page but do not know how to force the download to work. I get the file name returned in the "content disposition

I have not tried it, but I think you can do it using pub.client.http service. I would be similar to URLConnection in Java programming.
Good Luck

I am using this service but I cant find where the file is or if it is being returned like an ie issue of the same command when you get the save as screen.

According to documentation the output file will be in the output parameter “Body” in form of byte or stream (depending on the loadAs value.

Try using loadDocument to get the file from web.

Note that loadAsDocument is for XML or HTML files. If you have a different contentType use pub.client:http. See the Built-In Services Manual for details.

If it is a large file, I would get it back as a stream and write it out to disk before processing it.

I am doing something similar. Getting the file using pub.client:http. These files (can be a .doc, .xls, .pdf or .rtf) are coming back in a MIME envelope, so I am parsing the body out using webMethods services and writing it to a file system using ByteArrayInputStream and FileOutputStream.