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Re: questions

On Wed, 12 Apr 2000, Timothy Reaves wrote:
> I've read over the tutorial.  Ozone looks interesting, but I have a
> few questions.
> 
>     What I'm interested in knowing is how sessions are handled.  Are
> more than one person allowed to connect to the odb at once?
Yes. You can access the db from several clients and/or several threads. 

ozone uses a one-transaction-to-one-socket mapping. This works well and allows
several threads to run as independently as possible. On the other hand one
could expect problems when more then 1000 connections are open. I read this
somewhere but did not test that many connections yet.

> 
>     How is object locking handled?
When a method on an object is invoked the transaction implicitely acquires a
READ lock. If the method changes the state of the object then the programmer
has to mark this method so that the transaction can acquire a WRITE lock.
Currently there are two ways to do so: mark the method in the Java interface
source, use a XML class descriptor. You can find sample code of both in the
ozone samples.

> 
>     What about object resolution?  How many objects deep are brought
> over RMI?  The object itself (level 1), it's referenced objects (level
> 2)?
Try to get the idea of proxy objects. If we transfer non-database objects then
they are just serialized. If we transfer database objects as parameter of RMI
then just the the proxy is transfered.

> 
>     What about stability of the odb?  Is anyone using this, or is it
> still development level?
It is still work in progress. I don't know what kind and how many projects use
ozone today.


Falko
-- 
______________________________________________________________________
Falko Braeutigam                         mailto:falko@softwarebuero.de
softwarebuero m&b (SMB)                    http://www.softwarebuero.de