John writes:
> With the recent article in NewsWire, Java/iX is at the top of my mind. I
> haven't been inclined to download the goods from Jazz because I am not
> doing any web stuff from the HP3000.
Ah, but Java's not just for breakfast anymore.
> So I have to ask, what can Java/iX do for me.
It's a programming language. You write programs in it :-)
It has also got extensive libraries for things like networking etc.,
and Mike Yawn at HP has written a set of TurboImage classes that let
you access Image databases.
There are lots of reasons why Java is a better way to do software
development, and not all of them are the things that Sun touts.
After two years of playing with it, I'm more convinced than ever
that I'd want to write everything in Java if I could.
Unfortunately we're not yet to the point that you can just throw
out all your COBOL and replace it with Java. Also don't forget
that learning to design and write Object Oriented systems is not
a skill that's trivial to acquire.
Here are some possible Java + 3000 scenarios:
1) Java applets in web pages served from the 3000
You can write Java programs using any Java development tool and
load the code for these programs (applets) on the 3000 where a
web server like Apache can serve them up as part of a web page.
These applets could then talk to C programs or CGI/Perl programs
back on the host. This does not require that you install Java/iX
on the 3000 at all, since the Java code will be running on the
PCs, not on the 3000.
2) A Java Client/Server environment.
As in #1, a Java user interface runs on client PCs. The client can
either be downloaded from a web server, or it could be a standalone
application installed on the PC. The client would communicate with
a server on the 3000 that was also written in Java. This *would*
require Java/iX on the 3000 in order to run the server. Because
both the client and server are in Java, it makes the development
easier, and you can take advantage of Java to Java communication
facilities like the RMI Remote Objects system.
3) A standalone Java application on the 3000.
No web, no GUI, no Client/Server, no TCP/IP, etc. Just good old
fashioned HP3000 application programs that happen to be written
in Java rather than COBOL, C, or whatever.
So far there have not been too many people actually doing #3, though
a lot of people are thinking about it. Currently most of the
effort is going into developing things like #1 and #2, since they
involve the web.
> Ok object orientation and reusability is good. But for many
> of my users sitting at their HP700/98 terminal, how would a Java/iX
> application look and work for them.
You can write a Java program just like you write a COBOL/iX or a C/iX
program today. Also just like C and COBOL, the Java language does not
have a built-in mechanism for screen handling on a character mode
terminal. You would have to either call V/Plus from Java (which
can be done though I don't know of anyone who has tried it yet since
you would have to write some C language stubs to call V/Plus from
Java code), or write/acquire a screen handling package of some kind.
This probably wouldn't be that hard to write, but it's not something
that exists today as far as I know.
> Do Java/iX compile to a NMPRG or is this an interpreted program.
The normally interpreted universal Java code is automagically translated
into native PA-RISC (a'la NMPRG) at runtime, so it's somewhere in
between interpreted and NMPRG. In the future you should be able to
produce NMPRGs.
There are still some performance and resource usage issues in the
current version, but things have been improving steadily over time.
HP is making large investments in Java on the HP-UX side of the
company, and the 3000 is benefiting from this by leveraging and
porting those efforts to MPE.
> Also the way I remember it, Java was supposed to run in a "sandbox"
> so that it couldn't interfere with the executing client. Does this
> still apply?
That only applies to Java "applets" that run in a Web Browser. Java
"Applications" (ordinary programs) have none of those restrictions.
G.
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