Re: OJB unstable in Client/Server mode?

[Thomas Mahler]

Hi Martin,

Martin Burger wrote:
> Hello,
>
> the features of OJB as described on
>
> http://jakarta.apache.org/ojb/features.html
>
> are very promising, so we decided to use OJB in our project instead
> of JDO Genie.
>
> At first, we tried to use 0.9.8 in our application. Because many
> clients access the data in one database we decided straightforward to
> use 3-tier architecture without an application server. An
> application server would be overkill for our small application.

The OJB c/s mode is not necessary for such a scenario. Just run all your clients in singlevm mode. You will still have proper transaction isolation in this mode!

OJB c/s mode is meant as a means to provide scalability for AppServer based applications. It should be used as a last resort only if there is no other way to scale the app server machine.
In your case there is no such scalability bottleneck, as you don't want to use an application server. (of course the db could also become a bottleneck, but OJB c/s won't help here too!)

> The first steps were very frustrating, even the simplest techniques
> as described in tutorial 1 didn't work. If we use OJB in standalone
> mode and connect via JDBC to the database everything works fine. But
> as soon as we switch to Client/Server mode the server throws many
> many exception like this one:
>
<snip long trace/>

>
> What do you say? Are this really bugs or aren't we able to run
> OJB properly?
>

Bugs!
This is a known issue. The todo.html in the docs folder mentions that I did not manage to get c/s mode fixed for the 0.9.8 release. (c/s mode is not used that much, thus I'm a bit lazy with it...)

As far as I can see, there is no hard reason why you should work with c/s mode in your scenario. Just use singlevm mode and everything will be OK.

cheers,
Thoma

> Regards,
>
> Martin Burger
>
>
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