Re: Real world Java Scenario (was RE: IBM pushing Java)

[Blair Wyman <wyman@xxxxxxxxxxxx>]

Excerpts from midrange-l: 24-Mar-99 Real world Java Scenario (w..
"Stone, Brad V @ppress-t (2763*) 

> Java gurus:  Please see scenario 

I am not a Java guru -- more of a Java proselyte -- but I will put my
unbounded ignorance on public display to get the discussion rolling a
little.   

(FWIW, a sister list to this one --  JAVA400-L -- is starting to get
some interesting traffic after a long period of relative silence.  That
might be a neat place to post this scenario, too.) 

> Scenario JavaScenario = new Scenario(): 

> try { 
> You've just created a Java app (with swing) that lets the user view order 
> status information.  you have 30 users you want to give the program to. 

> Questions QuestionsforJavaGuru = new Questions(4); 

> 1. What are the steps to do this?  

A key question is probably: "Can this application be distributed and
executed as an applet?" 

The restrictions on unsigned applets are somewhat cumbersome, but the
primary restriction that "an unsigned applet can only connect to the
host that served it" is not as restrictive as it might appear, provided
your AS/400 is both your web-server and your data store. 

If the application can be distributed as an applet, then any user with a
Java-enabled web browser can run it.  Of course, the sensitivity of the
data might forbid it from being "generally" available, but there are
surely security measures that can be taken, both at the logical link
layer (SSL) and the application layer (password-protected access?)... 

So, assuming optimistically that 'applet' is a viable model, our
handy-dandy 'ViewStatus' applet would prompt for input, connect to the
AS/400 that had served it up, and query the machine for the order info 
(hand-waving hand-waving hand-waving).   

Then, the applet would simply (yeah, right) format the report output as
HTML (maybe XML?) and give it back to the browser to show to the user. 
Voylah. 

> 2. What happens when you make a change to the java app?  
Since the applet is always served from the central webserver, every user
always gets the latest (provided there aren't browser-cache effects...) 

> 3. A new Version of java or swing comes out.  You want to use it.  What 
> then? 

In the 'new version of Java' case, (swing notwithstanding) you must wait
until the browser supports it.  (Yuk) 

For swing I'm not sure, but I *think* that the server "serves up" the
swing implementation JAR file "over the wire," so that the users will
get the one you use.  (This seems expensive -- swingall.jar is not a
small file -- but it just has to work that way, doesn't it?  Please
correct me if I'm wrong.)   



> 4. Now, add 10 more plants located in different locations througout the 
> united states with 30 users each.  How does this affect 1-3? 

If the users at the other 10 (or 100 or 1000) plants have Java-capable
browsers and network connectivity to the host then you're done already,
provided the network has the bandwidth and the  server has the
horsepower to scale up commensurately.  (IMO the AS/400 is absolutely
best-of-breed in scaling up...) 

> This is real world stuff that we all already know how to do with RPG. 

> Let's hear from the Java gurus on this one.  I'd be interested. 
> } 

Other scenarios are undoubtedly possible with stuff like 'signed
applets', and 'ORB over IIOP', and 'RMI' and 'CORBA' and all the other
wonder-fungi in the mysterious alphabet soup of 'net development, but
IMO the bottom line is that Java is evolving from 'bouncing skulls on
web pages' towards solving the real-world stuff you mention, albeit in
fits and starts. 

Anyway, I'd love to hear from a Java guru to let me know how loopy I
am...  I've got a thick skin :) 

-blair 

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