Note Synchronization Brainstorming

Bugzilla

Syncing is a very important/requested feature, up there with bulleted lists
Sharing notes is out of the scope of this feature
Should have two modes of syncing:
- Enter storage URL, and use webdav/ftp to do really simple async background syncing
- Using Avahi to do automatic sync between nearby computers
These two can share a lot of code by making Tomboy run a very very simple webdav server and then just using Avahi to advertise the address.
Some reference code exists:
- http://live.gnome.org/Tomboy/NoteSharing
- http://svn.gnome.org/viewcvs/tomboy/branches/tomboy-sharing/
Merge conflicts can be dealt with by keeping the local note, create a new note containing the foreign content and then just appending a link to the top of the local note linking to the foreign note

Use a WebDav server as the master copy of notes
To connect, a user simply needs to enter the URL of the WebDav service, a username, and password
Synchronization occurs in the background automatically
- Initially, we'll implement a manual sync (user has to press some sort of button to make it happen)
- Eventually, allow the user to set how often an automatic sync should occur
More details in this IRC Log
Will need to deal with credentials (storing, caching, etc). Should we offer gnome-keyring integration for GNOME users?
Could design this such that there are many possible backends (ie, sync directly with a Subversion repository). Mono.Addins could help make this extensible.

How does a syncing client recognize a deleted note (and not re-add it)?
- Keep file that records rev number, adds, modifies, deletes (probably don't need rev numbers for individual notes, now)
What about generated notes? NotD? New notes with same title? (all of these have different UUIDs)
- Will have to somehow check note titles in addition ot UUIDs.
Emulating atomic commits...can we actually do this? How does svn work over file:/// connections?
Is a rename different than other modifications?
- Probably not from the server point of view, but the client has lots of things to worry about with a rename. Our notes do not live in isolation; renaming one note will affect the content of any notes that link to it. In theory, if one client renames a note, all of that client's linking notes should be updated as a result. In that case, once that client syncs, another client will only have to worry about making sure its new and modified notes link correctly to the renamed note.
- Note rename conflicts could potentially be a nightmare. Maybe we should sync entirely based on note title?
What modifications should be synced?
- Title, contents, tags, last-modified-date (for recent notes menu), pinned/unpinned, startup-note, size/position
  - Syncing size/position may be a problem across different display resolutions/types.

User makes changes
- Adds, modifies, deletes (modifications are marked in note XML, or in manifest?)
User initiates sync
Connect to server
- Involves getting stored credentials, or prompting
Update from server
- Check manifest
  - Local .tomboy/manifest.xml lets client know last synced revision
  - Remote manifest.xml lists revision actions
    - "12345 [A] UUID1, UUID2 [M] UUID3 [D] UUID4"
- Handle Adds
  - Generated notes (NotD) may need special handling, make sure to check titles
- Handle Deletes
  - If there are local modifications on deleted notes, prompt user to re-add or delete (or automatically re-add?)
- Handle Modifications
  - In case of local modification, prompt user to pick between (diff-like display? auto-merge? worried about adding foreign note...because we were assuming that the titles need to match)
Send updates to server
- Lock (locks can expire)
- Get incremented rev number
- Handle Adds
  - Upload file marked with rev number
- Handle Deletes
  - Delete file from server
- Handle Modifications
  - Update took care of merges/conflicts/etc
- Upload file marked with rev number
- Update remote manifest.xml
- Release lock
- Update local manifest.xml
Display sync status to user (should this dialog be integrated with the update/merge/etc prompts?)
Rinse and repeat