running different plugins within a java application in different JVMs

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dima.alina@gmail.com - 13 Mar 2006 17:00 GMT

Hello everyone,

I am developing an application that supports loading plugins. It is
using the JPF framwork. The problem that I am having is that I want to
start each of the plugins within the application in different java
versions (start a JVM within another JVM). Currently, the plugins are
running as parts of my main application and not as different
applications...this is what JPF supports.

Can anyone please help me with this? It is really important that I
manage to do this.

Thanks alot,
Alina

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Jan Thomä - 14 Mar 2006 13:03 GMT

> I want to
> start each of the plugins within the application in different java
> versions (start a JVM within another JVM).

Just out of curiosity, why is this a requirement. Why cant the plugins
be running within the same JVM?

Best regards,
Jan

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dima.alina@gmail.com - 14 Mar 2006 13:49 GMT

Because the plugins that are to be loaded to the application are
different: one might be compiled and running in 1.4 but not in 1.5 (for
whatever reason), another might be running in 1.5 but not in 1.4....
since the plugins are loaded to my application (they don't start as
different applications, but within my main application) I need to not
only start them up, during runtime, in an appropriate JVM (1.4, 1.5,
etc) but also use their classes within the JVM of my application.

Alina

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Jan Thomä - 14 Mar 2006 14:26 GMT

> Because the plugins that are to be loaded to the application are
> different: one might be compiled and running in 1.4 but not in 1.5 (for
[quoted text clipped - 3 lines]
> only start them up, during runtime, in an appropriate JVM (1.4, 1.5,
> etc) but also use their classes within the JVM of my application.

Hmm,

afaik, 1.5 should be backwards compatible to earlier JVMs, meaning 1.4
code should work on 1.5 without recompilation. I might be wrong on that
but using a 1.5 JVM should provide a host for all plugins no matter
which JVM version they were compiled against. Then you shouldnt have a
problem accessing their classes from within the main application.

Jan

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Oliver Wong - 15 Mar 2006 18:26 GMT

>> Because the plugins that are to be loaded to the application are
>> different: one might be compiled and running in 1.4 but not in 1.5 (for
[quoted text clipped - 11 lines]
> which JVM version they were compiled against. Then you shouldnt have a
> problem accessing their classes from within the main application.

There are some tiny backwards compatibility issues. I've personally
never encountered any of these issues in practice, but I know of them
because I got into an argument with someone about just how backwards
compatible Java is.

For example, between 1.5 and 1.4, on X windows servers, Drag and Drop
*MIGHT* behave differently, depending on the underlying implementation.

Like I said, very minor differences.

- Oliver

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Monique Y. Mudama - 15 Mar 2006 00:17 GMT

>> I want to start each of the plugins within the application in
>> different java versions (start a JVM within another JVM).
>
> Just out of curiosity, why is this a requirement. Why cant the
> plugins be running within the same JVM?

I don't know, but it can get awkward if you use static fields in an
applet and the user opens the applet twice ...

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monique

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running different plugins within a java application in different JVMs

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