Re: HttPrevayler

Klaus Wuestefeld <[email protected]>
Newsgroups gmane.comp.java.prevayler
Message-ID <[email protected]>
> If I understood this correctly, it won't be possible to take snapshots
> and eventually that would mean a long start-up time.

You are right.

We are planning of defining an http request that HttPrevayler, the
journaling reverse-proxy, on startup, can send to the web app and ask
it: "Web app, what is the last transaction id you have?"

The web app would only be in charge of doing the snapshot then, which
is a much simpler task (trivial on Java and .NET) than creating the
transaction classes and using them.

Ralph Johnson, co-author of "Design-Patterns", has reported on this
list about a system of his that is in use for years only with the
transaction log and no snapshots. He had a relatively low transaction
rate, of course.


> Also, although it is transparent the app must still be a deterministic system.

Sure.

Klaus.

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