JEP and JPype in a single process

[skn]

Hello,

I have written a very simple java class file, which invokes a Python script
using JEP.

Code snippet:-
-------------------
Jep jep = new Jep(false);
jep.runScript(" C:\\temp\\tests cript.py");
jep.close();

Now inside this Python script I want to make Java calls using JPype.
If I use startjvm() inside this Python script, a Runtime Error (exception)
is thrown.
Also tried attachThreadToJ VM(), but doesn't work, again Runtime Error.

Any clues as to how I could achieve my goal??
The interaction shown below should happen in a single process.

JAVA ==> jep ==> PYTHON ==> jpype ==> JAVA

Regards,
skn

[Konstantin Veretennicov]

Re: JEP and JPype in a single process

On 6/20/05, skn <skn@skn.com> wrote:[color=blue]
> Hello,
>
> I have written a very simple java class file, which invokes a Python script
> using JEP.[/color]
.. . .[color=blue]
> Now inside this Python script I want to make Java calls using JPype.[/color]

I am not familiar with either Jepp or JPype, but I spotted this
snippet on Jepp page (http://jepp.sourceforge.net/):

import jep
FileInputStream = jep.findClass(' java.io.FileInp utStream')
try:
fin = FileInputStream ('adsf')
except jep.FileNotFoun dException:
print 'Invalid file'

Are you sure you need to call JPype?

- kv

[Steve Menard]

Re: JEP and JPype in a single process

skn wrote:[color=blue]
> Hello,
>
> I have written a very simple java class file, which invokes a Python script
> using JEP.
>
> Code snippet:-
> -------------------
> Jep jep = new Jep(false);
> jep.runScript(" C:\\temp\\tests cript.py");
> jep.close();
>
> Now inside this Python script I want to make Java calls using JPype.
> If I use startjvm() inside this Python script, a Runtime Error (exception)
> is thrown.
> Also tried attachThreadToJ VM(), but doesn't work, again Runtime Error.
>
> Any clues as to how I could achieve my goal??
> The interaction shown below should happen in a single process.
>
> JAVA ==> jep ==> PYTHON ==> jpype ==> JAVA
>
> Regards,
> skn
>
>[/color]

You're trying to do something I hope to make possible somewhere down the
road ...

As of today, I do not think it is possible. JPype does not provide a way
to initialize the JVM-bridge system except for startJvm .. which seems
to be prohibited when a JVM is already running.

AttachThreadToJ VM will only work once the JVM-bridge system has been
initialize.

I will look into providing a sister method to startJVM to attach to the
currently running JVM instead of starting a new one. IF it does not
require major changes I will release it as 0.5.1. If you'd like you can
submit an enhancement request on the JPype sourceforge page, so this
doesn't get lost.



--
Steve Menard
--------------------
Maintainer of http://jpype.sourceforge.net

[Steve Menard]

Re: JEP and JPype in a single process

Steve Menard wrote:[color=blue]
> skn wrote:
>[color=green]
>> Hello,
>>
>> I have written a very simple java class file, which invokes a Python
>> script
>> using JEP.
>>
>> Code snippet:-
>> -------------------
>> Jep jep = new Jep(false);
>> jep.runScript(" C:\\temp\\tests cript.py");
>> jep.close();
>>
>> Now inside this Python script I want to make Java calls using JPype.
>> If I use startjvm() inside this Python script, a Runtime Error
>> (exception)
>> is thrown.
>> Also tried attachThreadToJ VM(), but doesn't work, again Runtime Error.
>>
>> Any clues as to how I could achieve my goal??
>> The interaction shown below should happen in a single process.
>>
>> JAVA ==> jep ==> PYTHON ==> jpype ==> JAVA
>>
>> Regards,
>> skn
>>
>>[/color]
>
> You're trying to do something I hope to make possible somewhere down the
> road ...
>
> As of today, I do not think it is possible. JPype does not provide a way
> to initialize the JVM-bridge system except for startJvm .. which seems
> to be prohibited when a JVM is already running.
>
> AttachThreadToJ VM will only work once the JVM-bridge system has been
> initialize.
>
> I will look into providing a sister method to startJVM to attach to the
> currently running JVM instead of starting a new one. IF it does not
> require major changes I will release it as 0.5.1. If you'd like you can
> submit an enhancement request on the JPype sourceforge page, so this
> doesn't get lost.
>
>
>[/color]

OK .. it now works. There are a few caveats that cannot be resolved
until either JEP and JPype can somehow cooperate or I finish what I
started and basically fold the JEP functionality in JPype.

I will release the new functionality in as version 0.5.1. The "gotchas"
are going to be in a readme-jep.txt file.

--
Steve Menard
--------------------
Maintainer of http://jpype.sourceforge.net

[skn]

Re: JEP and JPype in a single process

Thanks for your prompt reply, Steve.
Just one suggestion, may be the startJVM method's implementation can itself
be changed to check for already existing JVM.
Of course this will also mean a change in shutdownJVM() semantics. If JVM
has been started earlier(not using startJVM()), shutdownJVM() should be a
do-nothing function.

Another question I had was, is there any option to suppress the JVM activity
report that gets displayed. For e.g.,

JVM activity report :
classes loaded : 26
JVM has been shutdown

I know I can do it by re-directing the std err to NUL.
But is there any other option?

With best regards,
skn

"Steve Menard" <foo@bar.com> wrote in message
news:MXFte.4576 6$Fn.345638@web er.videotron.ne t...[color=blue]
> skn wrote:[color=green]
> > Hello,
> >
> > I have written a very simple java class file, which invokes a Python[/color][/color]
script[color=blue][color=green]
> > using JEP.
> >
> > Code snippet:-
> > -------------------
> > Jep jep = new Jep(false);
> > jep.runScript(" C:\\temp\\tests cript.py");
> > jep.close();
> >
> > Now inside this Python script I want to make Java calls using JPype.
> > If I use startjvm() inside this Python script, a Runtime Error[/color][/color]
(exception)[color=blue][color=green]
> > is thrown.
> > Also tried attachThreadToJ VM(), but doesn't work, again Runtime Error.
> >
> > Any clues as to how I could achieve my goal??
> > The interaction shown below should happen in a single process.
> >
> > JAVA ==> jep ==> PYTHON ==> jpype ==> JAVA
> >
> > Regards,
> > skn
> >
> >[/color]
>
> You're trying to do something I hope to make possible somewhere down the
> road ...
>
> As of today, I do not think it is possible. JPype does not provide a way
> to initialize the JVM-bridge system except for startJvm .. which seems
> to be prohibited when a JVM is already running.
>
> AttachThreadToJ VM will only work once the JVM-bridge system has been
> initialize.
>
> I will look into providing a sister method to startJVM to attach to the
> currently running JVM instead of starting a new one. IF it does not
> require major changes I will release it as 0.5.1. If you'd like you can
> submit an enhancement request on the JPype sourceforge page, so this
> doesn't get lost.
>
>
>
> --
> Steve Menard
> --------------------
> Maintainer of http://jpype.sourceforge.net[/color]