Cannot display through rsh

[Harold L Hunt II]

Ben,

Ben Kim wrote:

> If Cygwin is not aware of java, which means the GUI
> app should not be able to display on my Windows
> machines, then why is it the case that number #1 in my
> example works?

You got it about exactly backwards from what Igor told you.

Java for Windows does not understand the X Window System. Java for 
Windows displays graphics via the Win32 GDI system.  Java for UNIX 
machines displays graphics via the X Window System.

Cygwin/XFree86 is an implementation of the X Window System.  Thus, 
setting DISPLAY on your UNIX machine to point to your Windows machine 
that is running Cygwin/XFree86 will cause the X graphics to show up 
under Cygwin/XFree86.

However, the Win32 GDI system is nothing like the X Window System.  It 
was not initially designed to be network transparent like the X Window 
System.  Thus, there is not a simple way to display Windows applications 
running on a remote machine.

Harold

   Meaning, when I'm on Unix, set the
> display to Windows, and run the Java GUI, the gui
> correctly displays on the Windows machine?
> 
> Ben
> 
> On Tue, 12 Aug 2003, Ben Kim wrote:
> 
> 
>>I am trying to call a script located on my Windows
> 
> box
> 
>>from my Unix box through rsh.  All the script does
> 
> is
> 
>>run a java GUI application that outputs some
>>information in standard out.  When I run this script
>>through rsh, the java process is up and running on
>>Windows (I also see output, also check task manager)
>>but the GUI frame does not show up.  On Windows, I
>>installed cygwin and xfree.  I started X via
>>xstartwin.  I also xhost + to allow any host to
>>remotely display on Windows.  I know display isn't
> 
> the
> 
>>problem because if I am on my Unix machine, if I set
>>the display to Windows, and run the java app locally
>>on Unix, the app correctly displays on Windows. 
> 
> Only
> 
>>if the I'm trying to rsh the same script on Windows
>>from Unix, this doesn't work.  Another interesting
>>point is that if I were to change the script on
>>Windows to run cygwin/xfree xterm instead of the
> 
> java
> 
>>app,  and from Unix rsh the script, the xterm
>>correctly displays.  But as soon as I put in the
> 
> java
> 
>>app, it does not display.
>>
>>To summarize:
>>  1.  From Unix, run java app on Unix, display to
>>Windows (works)
>>  2.  From Unix, rsh java app on Windows, display to
>>Windows (does NOT work)
>>  3.  From Unix, rsh cygwin xapps (xterm, xclock
> 
> etc)
> 
>>on Windows, display to  Windows (works)
>>
>>Does anyone know what this might be the case?  And
> 
> is
> 
>>there any way to get #2 to work?
> 
> 
> Ben,
> 
> There is no Cygwin-aware Java JDK.  This basically
> means that, unlike the
> Unix one, the JDK you're using on Windows is not using
> the X protocol to
> display windows, but rather the Windows GDI one.  In
> other words, you
> cannot do what you want without a VNC-like tool that
> would let you display
> *any* Windows native application using X.
>         Igor
> 
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