Re: many instances of Shark in one VM

Thanks Dave and Vladimir,

        So far, we have the following options.
1. Run a different instance of JBoss/Shark(thus, also a new JVM) for
each client. Not the best solution though.

2. Modify Shark code to allow multiple instances of the Shark engine in
the same JVM. This means changing all singletons to return multiple
instances and also to replace all static fields with instance fields in
the entire Shark code/impl classes(Is this correct?). Though I have not
read enough Shark code to say for sure, this may be a herculean task and
may not even be successful. (Sasa, am I right?) 

3. Use different classloaders as Vladimir pointed out. This seems to be
a good/viable solution. However, instead of just creating and loading a
new Shark.conf for each engine instance I will have to create a new
war/ear for each client. Also a maintenance headache when we have to
update code. (Anyone have any suggestions about multiple classloaders?)

4. Try using SharkCorba server as Dave suggested, but this would be the
last option as we would have to rework everything we have now.

Thanks a lot for all the help,
Roshan.    


On Tue, 2005-07-05 at 18:02, Vladimir Puskas wrote:
> Hello Roshan
> 
> you wrote:
> > Hi Sasa and others,
> > 
> >       Is it possible to have many instances of Shark in a single Java VM
> > or in JBoss? We are currently running one instance of Shark as a POJO
> > library with session bean wrappers in JBoss. 
> > 
> >       We are looking at providing BPM(using Shark) as a hosted service
> > to some of our clients. We'd like to have a different instance of Shark
> > (ie. one Shark and database instance per client) for security reasons
> > and also to separate the repositories etc. for each client. Running a
> > separate JVM/JBoss for each instance may be too expensive and not
> > scalable(?). 
> > 
> >      Shark does not allow you to configure more than one instance at a
> > time ('Trying to configure shark instance that is already configured
> > !!!'). Is there a way to start multiple instances, each with its own
> > configuration(ie. different Shark.conf)? In org.enhydra.shark.Shark, we
> > could make some changes to enable multiple instances, but it seems that
> > such a change would also have to be made in other classes such as
> > SharkEngineManager etc. 
> > 	Clustering is also another concern for such a system.
> > 
> >      Tips and suggestions are welcome from everyone.
> 
> AFAIK it's possible to achieve this using separate class-loaders, as in
> webapp class-loaders division. You should be able to have multiple
> JSPClient applications inside one web server. I've just confirmed this 
> by deploying sharkworklisthandler.war twice in Enhydra6.3(Tomcat5.5).
> 
> hope this helps


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