Yeah, I noticed that you were looking at mitosis again. That's good news.
Before I started working on mitosis I thought a multi-master replication system would be pretty easy - the complexity was surprising. The biggest problems (both with MM replication in general and in mitosis) are the cases that aren't so obvious at first (to me anyway) like adding new replicas, servers that are down for a while, concurrent overlapping modifications, large quantities of data, etc. For my use of mitosis everything had to work or at least fail gracefully. Data loss was unacceptable (I was replicating account balances) and having the server fall over or stop responding wouldn't be great, since this was a minor component of our system and not one that our users would want to watch - they would barely even know about it. I think mitosis is a decent enough implementation that almost works. The design seems reasonable - it almost has a configurable log store already for example. The transport seems overly confusing to me and I would love to see that replaced with an LDIF based format compatible with openLDAP, ideally with encryption support. There are some concepts which don't even seem to be used at the moment, like the tombstone entries and entry UUIDs. The entry UUIDs seem to be generated and stored in each entry, but never used. If we can be assured that all change log entries will be applied in order (as I believe they are at the moment) then I'm not convinced we even need UUID's. I'll keep monitoring this list and try to help out where I can. Martin >>> Emmanuel Lecharny <[email protected]> 09/01/2009 13:57 >>> Martin Alderson wrote: > I agree, given that the CSN interface implies that all implementors > have timestamp, replicaID and operationSequence it really doesn't seem > likely that anyone would want to make a custom CSN class. CSNFactory is > just as bad. > Cool, thanks Martin ! Btw, we are going to review the complete Mitosis code, and your insingth might be very valuable, as you worked on it. DO you think there are some areas we will have to dig ? Can you give us a feedback about the Good, the Bad and the Ugly ? Many thanks ! -- cordialement, regards, Emmanuel Lécharny www.iktek.com directory.apache.org
