I've tried to figure out how to post a file that I picked up with the GetFile processor as well as some additional params with a multipart/form-data Content-Type.
I tried to use the InvokeHTTP and the PostHTTP method put if I send the content of the file as message body the other params are not sent.
In CURL it works fine with this command:
curl -v -X POST -F "project-file=@/home/schiessl/demos/test_file.xlsx" -F "format=binary/text/xml/xls/xlsx" http://requestb.in/1kurdbb1
Any ideas on that?