1 - make a page with a data view and choose your file object as the data view object
2 - add a file manager; now you can upload a file
3 - add a save button; now you can save what you have uploaded
4 - download the file
5 - optionally you can also add a data grid to see a "table" of uploaded files which can be downloaded
6 - if you want to process a file you can add a button which triggers your custom mf from the data view/grid
7- if you want to publish your file to external apps you have to publish a rest service wherein you send your data binary/base64 back to the requester
8 - you can look the uploaded pdf's bij adding a button with a mf behind with a download file activity