I want to save annotations of individual users for the same identical PDF. Therefore I cannot acutally save the annotations to the PDF.
My usecase is export annotations as XFDF send the XML to a server, parse the XML to create persistable objects, persist these objects into a database. Upon the next visit of the user the user's annotations are loaded from the database, marschalled into XML an send to the Client in order to be imported into the PDFTron WebViewer.
I managed to successfully establish this roundtrip by parsing the XFDF XML with a custom xsd. However it would probably be more reliable if there was an official xsd.
Do you know of any official xsd?