Rich,
Thanks for the information. Regards,
-Sunil .K
----- Original Message -----
From: Rich Johns <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Wednesday, May 31, 2000 3:05 PM
Subject: Re: Singleton design/implementation techniques
> Sunil Kuchipudi wrote:
>
> > Seth,
> > I am not sure if you would need to enforce singleton type on design
pattern
> > when it comes to EJB. From what I know, the container will allocate and
> > manage the pool of beans and decide on the number of beans instances
> > depending on the traffic. As such, the bean developers should not have
to
> > worry about about concurrency control and threading issues. These issues
> > should now be handled by the EJB container.
> >
> > Based on this premise, I do not understand why some ppl are looking to
> > implement the singleton pattern. Please enlighten me if I am missing
> > anything here.
>
> Consider a situation where all beans would want to share a single
> service. The singleton class lives in the same VM as the beans. If
> beans are spread across VMs then there is a singleton per VM.
>
> >
> >
> > Thanks.
> > -Sunil .K
> > ----- Original Message -----
> > From: Seth Hawthorne <[EMAIL PROTECTED]>
> > To: <[EMAIL PROTECTED]>
> > Sent: Wednesday, May 31, 2000 12:32 AM
> > Subject: Singleton design/implementation techniques
> >
> > > We have worked with C++ for the past 5 years, but are new to EJB
> > design/implementation. One of our biggest challenges is knowing when to
map
> > C++ design paradigms that we are familiar with (signeltons, polymorpism,
> > ...etc) to EJBs and knowing when we should be thinking in terms of
different
> > paradigms.
> > >
> > > For instance, there are a number of places in our design where we have
> > "manager" objects that encapsulate a collection of objects from which
they
> > select an object to delegate work to. Such "manager" objects are
logically
> > singeltons, however, EJBs seem not to provide a direct representation
for
> > singeltons. This leads to a number of related questions:
> > >
> > > 1) Is this design approach reasonable? Are there any EJB patterns that
> > might apply?
> > >
> > > 2) We have seen several approaches to implementing singletons
mentioned in
> > this newsgroup. The first is creating an object bound using JNDI, and
the
> > second is creating an object with a static accessor. Which approach is
> > generally preferred? What are the pros and cons?
> > > Does using a JNDI based object pose the risk of a single point of
failure
> > or scaling problems?
> > >
> > > 3) When should the singleton objects be created and initialized?
Should
> > this always be done on server startup?
> > >
> > > Any and all input is greatly appreciated. Thanks!
> > >
> > > Seth Hawthorne
> > > OpenGrid
> > >
> > >
> >
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> >
> >
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>
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