A classic/common problem... What's your solution?
Hi,
I'm looking for the best solution to a 'problem' that I know many people have come
up against in the J2EE world...
Here's a quick example of the problem:
You have a class (not an EJB), say, "MaintClass" that creates (and holds a reference
to) a Thread that repeated does some work (for example scans a db for a certain entry).
MaintClass also has some methods on it to allow other objects to interigate it and
find out info about what it's up to and/or what results or info it might have available.
You want all classes (servlets/jsps & EJBs) within your J2EE environment to be able
to access a particular instance of this class (it is NOT a singleton) and call methods
on it.
The question is, what is the best way to get this class instantiated one or more
times as the App Server fires up, and where/how do you keep the references to the
instances so that they don't get garbage collected, and so that they can be 'found'
by all all other classes? Also, if you have a 'cluster' of app servers running, you
don't want to have the instances propigate accross the cluster, because there are
threads held by the instances.
Thanks for any suggestions!
Hi
Another approach would be to define a startup method(static)
which will instantiate the "MaintClass". This method can essentially be called by
a startup program which can hold the references of your "MaintClass" and can be delegated
to ejb's or servlets by means of handler methods.
But Michael's suggestion would be a good practise here as we are
dealing with things in the J2EE scenario
Regards
Pradeep
Michael Young <[email protected]> wrote:
Hi.
One approach might be to use a startup class to bind your object to the
JNDI tree. When you
bind to the JNDI tree you have the option to have the reference replicated
across the
cluster, or you can bind a local instance without replication.
HTH,
Michael
Dan wrote:
Hi,
I'm looking for the best solution to a 'problem' that I know many peoplehave come
up against in the J2EE world...
Here's a quick example of the problem:
You have a class (not an EJB), say, "MaintClass" that creates (and holdsa reference
to) a Thread that repeated does some work (for example scans a db fora certain entry).
MaintClass also has some methods on it to allow other objects to interigateit and
find out info about what it's up to and/or what results or info it mighthave available.
You want all classes (servlets/jsps & EJBs) within your J2EE environmentto be able
to access a particular instance of this class (it is NOT a singleton)and call methods
on it.
The question is, what is the best way to get this class instantiated oneor more
times as the App Server fires up, and where/how do you keep the referencesto the
instances so that they don't get garbage collected, and so that they canbe 'found'
by all all other classes? Also, if you have a 'cluster' of app serversrunning, you
don't want to have the instances propigate accross the cluster, becausethere are
threads held by the instances.
Thanks for any suggestions!--
Michael Young
Developer Relations Engineer
BEA Support
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