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setting up classroom lab

P: n/a

I have inherited the responsibility of setting up a college lab for java
classes. I know next to nothing about java and have a few questions;

Our current configuration is;
Windows 2000 / XP lab machines with J2SE 1.4.2

Redhat 8.0 server with J2SE 1.4.2

Students telnet into the Redhat server and use PICO to create their scripts.
My question is;

If the student programs are designed to display GUI type boxes would this be
possible via telnet?

From my limited experience with Linux I would think they would need XWindows
access to do this.

???

Thanks,
-Giles


Jul 17 '05 #1
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12 Replies


P: n/a
glh-usenet wrote:
Students telnet into the Redhat server and use PICO to create their scripts.
For one thing, you don't write "scripts" in Java. You should double-
check to be sure you know whether the labs are for Java (in which it is
possible to write applets, applications, servlets, midlets, and more...)
or JavaScript (a completely different language used to write scripts for
web pages). If it's Java, and not JavaScript, then read on.
My question is;

If the student programs are designed to display GUI type boxes would this be
possible via telnet?

From my limited experience with Linux I would think they would need XWindows
access to do this.


Right. GUI programming is not possible via telnet, but it should be
possible if an X server is running on the Windows client machine,
assuming they have their DISPLAY environment variable set correctly if
they telnet to the RedHat machine.

--
www.designacourse.com
The Easiest Way to Train Anyone... Anywhere.

Chris Smith - Lead Software Developer/Technical Trainer
MindIQ Corporation
Jul 17 '05 #2

P: n/a

"Chris Smith" <cd*****@twu.net> wrote in message
news:MP************************@news.pop4.net...
glh-usenet wrote:
Students telnet into the Redhat server and use PICO to create their scripts.

You should double-
check to be sure you know whether the labs are for Java (in which it is
possible to write applets, applications, servlets, midlets, and more...)
or JavaScript
Thanks for the quick reply Chris. I will check with regards to Java versus
Javascript.
From my limited experience with Linux I would think they would need XWindows access to do this.


Right. GUI programming is not possible via telnet, but it should be
possible if an X server is running on the Windows client machine,
assuming they have their DISPLAY environment variable set correctly if
they telnet to the RedHat machine.


By X server do you mean something like VNC?
Thanks again!
-Giles
Jul 17 '05 #3

P: n/a
In article <46******************************@news.teranews.co m>, glh-
us****@comcast.net enlightened us with...

Right. GUI programming is not possible via telnet, but it should be
possible if an X server is running on the Windows client machine,
assuming they have their DISPLAY environment variable set correctly if
they telnet to the RedHat machine.


By X server do you mean something like VNC?


We use Hummingbird Exceed for X-Windows here.

An X-Server is a server (program) that tells Windows how to make windows
unix-style (or linux style). It translates things as appropriate and has
to run on the client machine. My Windows box has Hummingbird installed
and it can telnet, ftp, and do x-windows sessions. I telnet to the unix
server, set my DISPLAY environment variable (in the telnet session), and
run any program that uses a unix GUI and the x-windows client will make
the GUI run on my Windows box.
I can also set up a simple x-windows session in Hummingbird itself with
no need for a separate telnet window.

--
--
~kaeli~
All I ask is the chance to prove that money cannot make me
happy.
http://www.ipwebdesign.net/wildAtHeart
http://www.ipwebdesign.net/kaelisSpace

Jul 17 '05 #4

P: n/a

"kaeli" <ti******@NOSPAM.comcast.net> wrote in message
news:MP************************@nntp.lucent.com...
An X-Server is a server (program) that tells Windows how to make windows
unix-style (or linux style). It translates things as appropriate and has
to run on the client machine.

^^^^^^^^^^^
Thanks for the reply.
I think I am confused with some concepts here. If it is running on the
client machine then why is it call a server?

The component of Hummingbird (or any other X-Windows program) that runs on
the Windows box is considered the client piece, correct?
And the component that runs on the Linux box is the server?

Thanks again,
-Giles
Jul 17 '05 #5

P: n/a
glh-usenet wrote:
"kaeli" <ti******@NOSPAM.comcast.net> wrote in message
news:MP************************@nntp.lucent.com...

An X-Server is a server (program) that tells Windows how to make windows
unix-style (or linux style). It translates things as appropriate and has
to run on the client machine.


^^^^^^^^^^^
Thanks for the reply.
I think I am confused with some concepts here. If it is running on the
client machine then why is it call a server?

The component of Hummingbird (or any other X-Windows program) that runs on
the Windows box is considered the client piece, correct?
And the component that runs on the Linux box is the server?


No.
In X terminology, the machine with a screen and keyboard is the X-server,
think of it as the display server. The machine running the program (Red Hat
in your case) is then the client. The client program connects to the X
server.

I think it harks back to the days when the big mainframe was in charge of
everything and the displays were subservient devices on the end of
cluster controllers.

P.S.
Rather than setting the DISPLAY variable in your telnet session, which is
a right royal PITA to remember every time, using "ssh -X hostname" instead
of "telnet hostname" sets it all up for you.

Is there any reason why they can't use the local java installation rather
than write it on the server?

Have a look at BlueJ (http://www.bluej.org). Its a java IDE specially
written for teaching.

Steve
Jul 17 '05 #6

P: n/a
In article <34******************************@news.teranews.co m>, glh-
us****@comcast.net enlightened us with...

"kaeli" <ti******@NOSPAM.comcast.net> wrote in message
news:MP************************@nntp.lucent.com...
An X-Server is a server (program) that tells Windows how to make windows
unix-style (or linux style). It translates things as appropriate and has
to run on the client machine.

^^^^^^^^^^^
Thanks for the reply.
I think I am confused with some concepts here. If it is running on the
client machine then why is it call a server?


For the same reason IIS (or Apache) running on my local machine testing
my local html documents is still a server. :)
Or php running on my machine testing my php documents is still a server.
It serves up the php documents - the client is simply on the same
machine as the server runs on. The client in these cases would be a
browser.

I also have an SQL server installed on my local machine. A server merely
takes requests from a client and does something with them. The server
and the client can be, and often are for development, on the same
machine.

In the case of x-windows, the request (that is, something sends data to
something else and expects something to be done with that data) comes
from the unix box, so the real paradigm is that the unix machine is the
client for the x-windows server. For ease of discussion, we often call
the machine doing the telnet session the client and the machine that is
connected to is the server, but sometimes this is not entirely accurate.

HTH

--
--
~kaeli~
A man needs a mistress... just to break the monogamy.
http://www.ipwebdesign.net/wildAtHeart
http://www.ipwebdesign.net/kaelisSpace

Jul 17 '05 #7

P: n/a

"Chris Smith" <cd*****@twu.net> wrote in message
news:MP************************@news.pop4.net...
Right. GUI programming is not possible via telnet, but it should be
possible if an X server is running on the Windows client machine,
assuming they have their DISPLAY environment variable set correctly if
they telnet to the RedHat machine.


If I understand you correctly as long as an X server is running on the
Windows machines they can telnet and execute their GUI java programs?

Where does appletviewer come in to play with this?

Thanks,
-Giles
Jul 17 '05 #8

P: n/a
In article <8e******************************@news.teranews.co m>, glh-
us****@comcast.net enlightened us with...

"Chris Smith" <cd*****@twu.net> wrote in message
news:MP************************@news.pop4.net...
Right. GUI programming is not possible via telnet, but it should be
possible if an X server is running on the Windows client machine,
assuming they have their DISPLAY environment variable set correctly if
they telnet to the RedHat machine.
If I understand you correctly as long as an X server is running on the
Windows machines they can telnet and execute their GUI java programs?


Security allowing, yes.
Note that some machines will not allow telnet sessions.
Where does appletviewer come in to play with this?


appletviewer is for applets. Applets are used in a browser environment,
such as IE or Netscape. appletviewer simulates a browser for people who
can't, for some odd reason, test their applets in an actual browser.
I myself have never found reason to use it.

A GUI java application using the normal swing or AWT classes does not
use appletviewer.

--
--
~kaeli~
Synonym: the word you use in place of a word you can't
spell.
http://www.ipwebdesign.net/wildAtHeart
http://www.ipwebdesign.net/kaelisSpace

Jul 17 '05 #9

P: n/a
glh-usenet wrote:
If I understand you correctly as long as an X server is running on the
Windows machines they can telnet and execute their GUI java programs?
Yes, assuming the X server is set up to allow it.
Where does appletviewer come in to play with this?


Well, I'm not sure it does. I suppose that appletviewer is one example
of a GUI application that could be run that way.

--
www.designacourse.com
The Easiest Way to Train Anyone... Anywhere.

Chris Smith - Lead Software Developer/Technical Trainer
MindIQ Corporation
Jul 17 '05 #10

P: n/a

"Chris Smith" <cd*****@twu.net> wrote in message
news:MP************************@news.pop4.net...
glh-usenet wrote:
If I understand you correctly as long as an X server is running on the
Windows machines they can telnet and execute their GUI java programs?


Yes, assuming the X server is set up to allow it.


Ok, now I am making definite progress. I will look more into finding an X
Server for Windows that can accomplish this.

Thanks so much Chris, Kaeli and Steve!!!

-Giles
Jul 17 '05 #11

P: n/a
Tom
kaeli <ti******@NOSPAM.comcast.net> wrote in message news:<MP************************@nntp.lucent.com>. ..
<much snipped>
appletviewer is for applets. Applets are used in a browser environment,
such as IE or Netscape. appletviewer simulates a browser for people who
can't, for some odd reason, test their applets in an actual browser.
I myself have never found reason to use it.


One reason for using appletviewer is that browsers cache data. If you
make a change in your applet, simply refreshing the page will usually
not show the changes because the browser will see that the file is
already in the cache and retrieve the cached file instead of
"downloading" the new one. The appletviewer will show the changes
more reliably. That said, it is still adviseable to open applets in
an actual browser occasionally.

<snipped>
Jul 17 '05 #12

P: n/a
I believe it was glh-usenet who said...

"Chris Smith" <cd*****@twu.net> wrote in message
news:MP************************@news.pop4.net...
glh-usenet wrote:
> If I understand you correctly as long as an X server is running on the
> Windows machines they can telnet and execute their GUI java programs?


Yes, assuming the X server is set up to allow it.


Ok, now I am making definite progress. I will look more into finding an X
Server for Windows that can accomplish this.


http://x.cygwin.com
Jul 17 '05 #13

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