Re: [Springframework-developer] reloading/hot swapping of beans

[Rob B. <rob...@ve...>]

While your on the topic of reloading / hot swapping of beans, what are your
thoughts on JMX?  Reloading / hot swapping of beans & JMX would go nicely
together.

I've been thinking a bit about Spring & JMX lately.  My original plan was to
implement some sort of a custom configuration repository that the JMX Mbeans
could update.  A database or the like.

Once the configuation changes were made, I would somehow signal my app.  The
app would load a second instance of spring, and then "swap" it with the
original at the appropriate time in the applications cycle.  Spring would be
used as a "factory" for all the objects in the application, and thus when
the new spring instance was loaded the new configuration would be used.  I
would use some sort of unit of work pattern to maintain a reference to the
"old" spring instance until that unit of work was completed so there would
be no issues with the config changing halfway through.

The primary issue I had with this setup is singletons.  If I have two
instances of Spring, then I don't have a true singleton anymore (I could
always revert to the "singleton" pattern if need be - yuck).  This may be
fine in some situations, but not ok in others.  Also, I would like some way
to "copy" state from the old singleton into the new one built into the
framework.

I just wanted to get this out there to see what people think about how to go
about JMX enabling spring.  Rod had said he had some thoughts on it a while
ago (or in his book?).

I haven't done a very good job of explaining this, but I think this would
work.  I can explain it better later if this is an area of interest to
people.

Later
Rob

> Yes, I think we could do this pretty easily. But I wouldn't want it to be
> the default.
>
> Regards,
> Rod
>