Let me escalate this internally. I know there are some nuances with Multipart vs pure binary requests, but need to get the details. Escalating internally.
File uploads in Jive apps have been the bane of my existence for 3 years now. There doesn't seem to be an elegant way to achieve this.
The two options I've been using are
1) move the file upload to an iframe loaded directly from my backend server
2) Use a file upload control capable of cross domain posting (we use dropzone.js), and configure the backend server accordingly for x-domain requests
Both options usually require the creation and use of a single-use token (appended as a query parameter usually), as the request will not be signed by Jive
Yes, I got similar details late last night. My memory had to do with binary requests to jive, but when the target is a remote service ... Solutions like the ones Nils has described are the only viable solutions. :/