So there's a new round of talk lately about syncing and the trouble involved, thanks to some changes in Google Reader's behavior and the desire to find a new safe haven for RSS syncing. The best example is, unsurprisingly, from Brent Simmons:
However, the whole time I was reading this article, my brain kept yelling at me, louder and louder as time passed:
This is Lotus Notes! The system you're describing is Lotus Notes! It does syncing and deletion stubs and read marks! IT'S LOTUS NOTES!
This kind of thing would indeed be really easy in Notes/Domino, particularly if you were actually using the Notes client (though it wouldn't be much to look at). Subsets of data, managing deleted elements, timed refreshes from the source, storing each feed entry as its own entity, and offline access that can have its changed synced back to the master are all things that Notes has done since its conception - the only problem is that it's so ugly and arcane that mass-market appeal is nigh-impossible.
Nonetheless, it got me thinking about the viability of using Domino as a syncing server for this. You wouldn't be able to use NSF files in your RSS clients, which would make the job a bit tougher, but the new "XWork" licensing model would fit into this nicely. Scalability would be a serious concern, but the simple nature of the data would keep view updates quick, and it'd just be a bit of cleverness in the database layout to direct users to the correct place. Toss a couple clustered servers in there and you should have some good load balancing, too. The Domino Data Services API might be enough to handle data access from the client, but, if it's not, a couple simple agents would do it.
I'm sort of tempted to try hashing something out.