Hello Cyril,
as regards the "offline mode" as you describe it.
Probably, the only way to achieve this would be either:
* share the documents through some cloud service (DropBox, GoogleDoc) or similar that offers API that could be utilized for this at server side and that has applications ready, that users could install at their local computers
* create an own desktop application that would take care about synchronization with the server where the JoomDOC is installed
Technically, the transfer of data is not a big issue.
What IS a major issue in these cases is the data synchronization and change management. What if 2 offline users will be editing the same document at the same time?
If one connects to Internet and uploads it, the second one will then override it with his own changes.
There would have to be defined a locking mechanism, that would monitor when a particular user has dowloaded the original document, compare, if there have been other updates to it in the meantime and warn the user - or not allow upload of a document - in case there would be a risk of overwriting somebody elses changes.
If you are interested in this, we could certainly cooperate with you an implementation of such feature.
Best regards,
Michal