how can I keep a kind of global object (Singleton) in JBoss?

[davidchen]

Hi, there:

here is my problem:
1. we want to keep a copy of a huge database view in JBoss side (because, the view is huge, so, only one copy will be created, and maintained);
2. when request comes from client, we should check if that copy is outdated or not (ex. less than 10 mins since last update), if outdated, then update the copy from database, otherwise, just send the copy to clients.

We are using Jboss2.4.8, oracle9i. Currently, I think, to use RMI Service may be an option for this issue. So, thanks in advance if anyone have any clue for it.

Thanks
David

[david.salter]

Can't you just create a singleton and access it through a stateless session bean?

[darranl]

Can't you just create a singleton and access it through a stateless session bean?

No you can't

If you write singletons you need to be aware that the application server may create multiple instances of the singleton depending on classloaders and how many JVM instances the app server is running in.

[snavjot]

hi,

you can read the data from DB, create an object ans save at some JNDI location.

Now, just access the same JNDI location.

Is that good enough solution?
Navjot Singh

[kelle]

snavjot, I need to create a singleton object cache and this sounds like the solution I am looking for. I am not familiar with some of your terminology though. What is an "object ans." Could you please elaborate on your solution. Thanks.

-Kevin

[darranl]

"object ans" is a typo, the sentence should have read.

you can read the data from DB, create an object and save at some JNDI location.

[enterprisejavabones]

Another possible solution is to implement this database viewe as a managed resource, i.e. as a JMX MBean. Given that your needs require an updated copy, your get DBView() method (or whatever you call it) can load the DBView when first called and subsequently check for staleness on subsequent invocations.

Perhaps you may wanna have a look at implementing your managed resource (MBean) as a standard MBean, those are not too difficult to implement and may serve you purpose.

Cheers

[jigneshsr]

I think caching ur data in xml object probably a huge dom stucture is good one tohave