Re: starting JVM is slow -- JAVA400-L

Aaron,

I have some experience with both sides, rpg and java. In the last two years I 
have made some reviews of java projects in the as400 context realized by 
as400 rpg (or COBOL) programmers. main problem in (nearly) all projects was 
design. the applications where designed like rpg (procedural, not well 
modularized) and written in java. I didn't find inheritance and interfaces, 
there was no usefull package structure, Java Standards like Log4J, JUnit, 
Ant, where not be used. The situation was better, if frameworks where used 
and got worse, when rpg code was integrated. If they tried to integrate rpg 
code, they didn't find so many "components" in their rpg applications (most 
RPG applications mixup even the View layer with the database layer.
 
On Montag, 12. Januar 2004 21:23, Bartell, Aaron L. (TC) wrote:
> I will take fault then, but you had better qualify your statements when you
> make comments like yours.  They can catapult in to huge discussions when it
> all could have been stopped at the beginning by somebody clarifying their
> broad statements.

This huge discussions might be helpfull!!!

>
> Something more appropriate if you are sticking with your statement of "Best
> Practice" would be to say that Java holds no place on the iSeries except
> under an App Server like Tomcat or WAS.

It's near to this, the as400 has no client components for java, even no 
frontend components at all. In the missing packages AWT and Swing are the 
graphical GUI components and the print support of java too. So the as400 is a 
server machine from the java perspective of the world. Best practices of 
server java are defined with J2EE and thats the World of Tomcat, WAS, JBoss 
and upcoming Java WebServices. The Bridge to legacy applications (rpg, COBOL) 
in J2EE is CORBA, this components are missing on the as400.
There is one place left for java besides this: speeding up RPG/COBOL (single 
threaded) batch jobs by rewriting them in java to speed them up by making use 
of multithreading on multiprocessor as400s.
Another possibility might be to make use of java applications dealing with XML 
Data, or PDF, to bring this to the as400.

only my opinion

Dieter Bender

>
> Just my opinion though,
> Aaron Bartell
>
> -----Original Message-----
> From: java400-l-bounces@xxxxxxxxxxxx
> [mailto:java400-l-bounces@xxxxxxxxxxxx]On Behalf Of Dieter Bender
> Sent: Monday, January 12, 2004 2:36 PM
> To: Java Programming on and around the iSeries / AS400
> Subject: Re: starting JVM is slow
>
>
> Hi Aaron,
>
> I didn't say that calling RPG from java or vice versa is impossible, or
> slow,
> but whatever it would be, it would not be part of best practices. All
> papers
>
> talking about best practices, good design and things to avoid mention
> that's
>
> even no good idea mixing up java and C and JNI is designed for C. But JNI
> was
> designed for implementing the JVM and not to write applications using JNI.
> And JNI was designed for a multithreaded language like C and not for RPG.
>
> Dieter Bender
>
> On Montag, 12. Januar 2004 20:06, Bartell, Aaron L. (TC) wrote:
> > Just curious, what are your reasons for not calling RPG from Java?  I
> > have a Servlet in production calling an RPG program with PCML as the
> > intermediary, and it is very very fast.
> >
> > I agree that calling Java from RPG is pretty much useless unless it is a
> > batch process or if you have a huge machine.  People will tell you to use
>
> a
>
> > data queue or something similar, but that means you most likely need to
> > write your Java interface so it can run off of a completely validated
> > data queue record (meaning you don't collaborate with all the different
> > methods in a Java class).
> >
> >
> >
> > Aaron Bartell
> >
> > -----Original Message-----
> > From: java400-l-bounces+albartell=taylorcorp.com@xxxxxxxxxxxx
> > [mailto:java400-l-bounces+albartell=taylorcorp.com@xxxxxxxxxxxx]On
> > Behalf Of Dieter Bender
> > Sent: Monday, January 12, 2004 11:08 AM
> > To: Java Programming on and around the iSeries / AS400
> > Subject: Re: starting JVM is slow
> >
> >
> > Hi,
> >
> > IMHO best practice is: not to call java from RPG and vice versa.
> >
> > Dieter Bender
> >
> > On Montag, 12. Januar 2004 17:35, Ashish Kulkarni wrote:
> > > Hi
> > > I am calling Java program from RPG, and for the first
> > > time it is very slow, as it has to start the JVM etc,
> > > is there a way to imporve performance , what are the
> > > best practice to call java from RPG,
> > >
> > > Ashish
> > >
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-- 
mfG

Dieter Bender


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