Re: Switching to Java on OS/400 - got a few questions.

Thorbjørn,

We have used an Apache-based Tomcat release on the iSeries for a few years now. 
That application was written in RPGIV and rewritten in Java -- business logic 
and all. We have a couple of hundred users and a substantial transaction load. 
The database that supports this application has several key tables with +100 
million rows. Performance on an 825 is good and the users like it a lot better 
than the green screen applications it replaced. The speed of your network is 
also a much bigger factor in any web-based application than it is with a green 
screen application.

I have done a lot of benchmarking and we get much better performance running 
natively on the iSeries than on a Windows box. In some cases, I have had to 
adapt code to avoid problematic code. IBM may have been able to help in those 
cases but we do not have software support and I was able to find a work around 
fairly quickly.

I would write code differently if I were building a multi-tier application. I 
would cache aggressively and use more stored procedures. That would add some 
complexity but would be required to get similar performance.

We develop on a workstation and deploy to the iSeries. We have a development, 
test and production environment on the iSeries. The development environment is 
seldom used except for deployment testing, benchmarking and troubleshooting 
iSeries specific issues. We have strict seperation of duties and deploy using a 
hands-off process. Restarting is much slower on the iSeries (about a minute) 
but still acceptable.

--David Morris

>>> thunderaxiom@xxxxxxxxx 09/19/05 12:02 PM >>>
I am an experienced Javaprogrammer with Windows+Unix experience who have 
now for a while worked with creating frontends for OS/400 backbone calls 
using Eclipse on Win32.

Just for fun I tried installing and running Tomcat 5.0.30 beta the other 
day, with the intent of eventually porting our webapps to run natively 
on OS/400, but we are very careful since that is very new to us all.  
The sample JSP's and servlets was impressively quick!

I would therefore like to hear if there is experience in this forum 
regarding the following:

* The long startup time of Tomcat (50 seconds) is due to some 
precompilation to native code? 

* Can I use graphical applications (Swing) on OS/400 and use some 
software on Win32/Unix to see the output.  X Windows perhaps?

* I have seen that some corners of eclipse.org mention OS/400 binaries, 
but not for the native Eclipse application.   Is this available, or is 
it perhaps some Websphere package?   How do I access that (i.e. what am 
I to ask the system responsible) :)  Would Netbeans run?

* Do anyone use Java on OS/400 as a development platform, or is it 
solely for deploying applications?

* I found the qsh interface rather sluggish to work with.  Can I ssh to 
OS/400 instead and perhaps get a more responsive shell?

* What is the resource usage of Java programs under OS/400?  How can I 
tell for myself?  It is very important that we can determine accurately 
if this is a feasible path.

* Do anyone have performance numbers of JDBC-access using the best 
driver when running on OS/400?  We may have a very data processing 
intensive application where network performance may be a bottleneck if 
running on another host.



Any other suggestions, including further reading, would be appreciated.

Thanks in advance for any pointers.

Best regards,

    Thorbjørn Ravn Andersen