On Fri, 17 Dec 2004 14:35:56 +0100, Armin Waibel <[EMAIL PROTECTED]> wrote:
> Hi Oliver,
> 
> Oliver Zeigermann wrote:
> > On Mon, 13 Dec 2004 12:43:59 +0100, Armin Waibel <[EMAIL PROTECTED]> wrote:
> >
> >>The OTM layer is alpha state, so there will be much of "unchecked" code.
> >>Currently nobody works on OTM and for OJB 1.1 we try to move most
> >>services (e.g. locking,...) to the kernel (org.apache.broker.*). You
> >>could find the "old moved" locking version in org.apache.broker.locking.*
> >>This version (used by odmg-api) isn't as smart as the OTM version (any
> >>help to include the LockWaitStrategy from OTM is appreciated ;-)).
> >
> >
> > Thanks. This makes more sense, I still do not understand what
> > SerializableStrategy is doing?!
> 
> well, seems that this strategy lock the object for one entity other
> entity can't get read or write lock, only the owner entity can upgrade
> lock. Think in this case read==write, it only allows one entity to work
> on an object at the same time.

Yes, but why? I seem to remember that two phase locking with
read/write locks for all transactions is just enough. Or is this to be
sure that no other transactions with lower isolation inferfere?
 
> OJB has the following requirements:
> - pluggable components, e.g. when OJB run in j2ee compatible appServer
> we need a JMS based locking solution (run in clustered environments)

Hmmm. Could you explain this a bit? How is this suppost to work?

> - the timeout strategy needs to be pluggable, because in j2ee compatible
> appServer (OJB was used in session beans) it's AFAIK not allowed to
> manage Threads (it's done by the container).

Threads managed (blocked) using JMS? Is this the idea? Hmmm, I
understand for complex applications there is no other way than to
manage threads even in J2EE. I thought everyone does?!

> - OJB allows to specify the used locking strategy generally and per
> class, so the LockManager should be able to deal with different strategy.

This would be no problem. The lock manager supports both blocking and
non-blocking requests.

I would be glad if you had a look at the stuff and tell me if you
think it is suitable.

Oliver

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