According to the discussion thread below, the current approach to data
integrity in Weave is wiping server data every time there is a
mismatch between Weave version that wrote the data and currently
installed Weave version. In future this should be changed to warn
instead of wiping data if the installed version is lower than the
version the created the data. I guess this solution is good enough -
but only if all data comes from the Weave extension itself. As soon as
other extensions start registering their engines there will be
trouble.

In particular, Adblock Plus 1.1 will most likely be able to
synchronize through Weave. However, for the list of filters it will
ignore positioning of the filters because tracking position changes
isn't currently possible in Adblock Plus (it was never necessary). A
future version might fix this - but if a computer with this version
and another with Adblock Plus 1.1 are synced there will be data loss.

I think the best solution here is versioning the data format per
engine. Each engine should have a number representing its data format
version, it should increase on each format change. So it would be
possible to wipe the server only for the engines where it is
necessary, and it would allow Weave to disable a single engine if it
is outdated (as well as inform the user about it). There should
probably still be a global data format version that should change
whenever some format detail changes that is common to all engines.

Does that sound like something Weave would implement? And as a side
question - any hints on how to deal with this issue in Adblock Plus as
long as it is not implemented?

Wladimir