Re: Java on AS/400

[Blair Wyman <wyman@xxxxxxxxxxxx>]

Excerpts from java400-l: 10-Feb'00 Java on AS/400 * Jay.D.
Fernando@hotmai (813*) 

> I need to know how to use JAVA SWING class's on the AS/400.....our
> version of OS/400 is V4R3...we guys have just now loaded AS/400
> Developer Kit for Java....checked out some simple pgms...they are
> working fine...but cant use AWT or SWING either....can anybody enlighten
> me on this issue. 

AS/400 doesn't have a graphical display, so it doesn't have any way to
show graphics "natively."  The current solution for running AWT
applications "unchanged" involves the use of something called "Remote
AWT" (RAWT), which requires the presence of a TCP-connected
graphics-capable machine with Java (and a special jar file) installed. 

What happens is that the application on the AS/400 does AWT processing
in the normal fashion, but all actual awt calls are "captured" by the
RAWT code and redirected across a socket to a process running on the GUI
machine.  There is some really fancy "proxy" stuff going on, and the
technology is extremely advanced.  However, graphics-intensive
applications do suffer a performance penalty that renders some
applications effectively unusable, but for very graphically lightweight
applications it is a possible solution.  FWIW, the performance of RAWT
has come a *long* way since its first incarnations, but even an order of
magnitude might not be enough for some applications. 

It is necessary to start a process on the GUI machine that "listens" for
connections from the application host, and it's necessary to specify a
special property on the HOST Java command line, but it does work. 

For some better detail, see: 
http://publib.boulder.ibm.com/pubs/html/as400/v4r4/ic2924/info/java/rzaha/devki
t.htm 
and click on the heading for "Running on a host without a GUI". 

Another option, if you are willing to change the code, is the use of
"ClassBroker for Java."  Obviously, this isn't feasible for
"shrink-wrap" applications, but if you are writing an application from
the ground up, CBJ offers much better potential performance than RAWT is
capable of. 

Both RAWT and CBJ come out of the IBM Haifa Research Lab, and we
couldn't ship Java without the wonderful efforts of these gifted
programmers. 

-blair 

  ___   _           Blair Wyman                  IBM Rochester 
 ( /_)  /  _  ' _   (507)253-2891            blairw@us.ibm.com 
__/__)_/_<_/_/_/_'  Opinions expressed may not be those of IBM 

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