Re: AS/400 and Java -- JAVA400-L

David Gibbs schrieb:
> <Dieter.Bender=zqRNUXuvxA0b1SvskN2V4Q@public.gmane.org>
> wrote in message
> 1036423799.3dc69277cafac@webmail.t-online.de">news:1036423799.3dc69277cafac@webmail.t-online.de...
> > things have changed with JIT and V4R5, but some
> "experts" didn't
> > recognize this, maybe they are not reading recent
> documentation.
> > Just have a look to the mainstream of java development,
> which takes
> > place on other boxes and yoe see were the future will
> be. if the as400
> > wants to survive as java plattform, then it will go
> this way too.
>
> Dieter:
>
> In some respects, I agree with that statement ... but you
> made some pretty
> bold, and quite specific, recommendations in your
> previous message ...
> before I consider them to be reliable, I really need to
> know what you are
> basing them on.
>
> I'll address my concerns with the statements directly
> ...
>
> > 1. read the recent manuals (Performance Capabilities
> Reference
> > recommends the JIT environment since V4R5!)
> > 2. don't use CRTJVAPGM on boxes > V4R5
>
> Which manuals is that?  I can't find it.
www-919.ibm.com/developer/performance/icprv5r1.pdf

www.ibm.com/servers/eserver/iseries/software/
websphere/wsappserver/docs/WAS35perf.pdf

http://as400bks.rochester.ibm.com/html/as400/v5r1/ic2931/info/rzaha/rzaha.pdf

>
> > 3. don't use the native driver, its buggy, use the
> latest Toolbox driver
>
> How is it buggy?  Are there APAR's out for it that
> haven't yet been PTF'ed?
> Using the native capabilities of the database has got to
> be better than
> using a JDBC connection.  Even it's local.

both have bugs (locking of records, typ mismatches calling stored
procedures, wrong results of getDouble()...), but for the toolbox
driver, those are solved in a short time. btw my benchmarks have shown,
that the diffrence in performance is < 5%. may depend on application,
no problem to switch a driver.

>
> > 4. don't use record level access (more IO Operations
> compared to SQL)
>
> Huh?  That's backwards.  Record level IO, while not being
> very portable, is
> far more efficient than SQL (at least for record
> processing).  I think Joe
> Pluta's research has shown that in spades.

there are statements from ibm that a single read is faster using sql
than RLA (not my experience). the main argument is: RLA is not enhanced
in future, ibm is working on sql only, your application won't benefit
of enhancments, if you use RLA.

>
> > 5. run your application server on inexpensive boxes
> > (Wintel, or Linux on Intel), if possible (scalability)
>
> Again, Huh?  No PC comes close to an iSeries in terms of
> scalability.  This
> is one of the systems primary strengths.

please read my statement from begin to end!!! if you don't need high
scalability, intel would be much cheaper.

>
> > 6. Don't mix Java with RPG and/or COBOL, the context
> change is
> > very expensive
>
> Where is this documented?

mainly in the jdk doku of as400, you'll find the url on top of this
mail.

>
> > 7. use all features of the as400 as database server,
> you've paid
> > for it
>
> While this is true ... being a database server is by no
> means the only thing
> the iSeries can do.

agreed, but the as400 is no all purpose machine, there are things other
boxes might do better.

>
> > 8. for maximal speed with minimal hardware requirements
> use
> > assembler and shift your bytes bit by bit
>
> This goes without saying ... all systems run faster at
> the machine level
> than the application level... but few programmers (in
> general) program at
> the machine level.

that will be the future of rpg too!

>
> david
>
>
>
>
>
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