Re: [g-a-devel] Questions about the gnome-mag design

[Carlos Eduardo Rodrigues Diogenes <cerdiogenes yahoo com br>]

Bill Haneman wrote:

> (sorry for replying to myself - this is a clarification)
> Bill Haneman wrote:...
>
> > Also, there are situations where the magnifier service may need to 
> > run on a different host from the client.  For instance, if you are 
> > running a remote application, you don't really want the magnifier to 
> > run remotely as well, because of the much larger amount of X traffic 
> > and the CPU requirements of the magnification service.  CORBA allows 
> > this at least in theory (although our current 'bonobo-activation' 
> > mechanism does not recognize remote servers).
The CPU requirements isn't is a big problem, because if you start the
gnome-mag in a remote machine, probably, this machine will have a better
CPU than the machine that is running the X Server. The X traffic is
really important, but I think that it's not a big problem, because we
have solutions like vino and xdmcp that works really fine, and how
gnome-mag uses the DAMAGE extension this problem is minimized. I raised
this aspect, because here in Brazil we have many places with old
machines, that will not support a good magnifier without delay, so is
more cheap buy a good server and use the old machines like dummy terminals.

> By this I mean that "bonobo-activation-server" doesn't report remote 
> magnification services to a client which is requesting an instance of 
> gnome-mag.  However, gnome-mag should work fine with remote _X 
> servers_ as far as I know - at least, I have used this feature in the 
> past.  (Carlos, did you get this working on your system? Maybe a bug 
> somewhere?)

no... here is the output of what I get when I call gnome-mag with this
command line in the remote machine:

#: magnifier -mv -t myip:0 -s myip:0

(magnifier:19579): Bonobo-WARNING **: Assigning a default value to a non
readable property 'source-display-screen'

(magnifier:19579): Bonobo-WARNING **: Assigning a default value to a non
readable property 'target-display-screen'

(magnifier:19579): Gdk-CRITICAL **: gdk_display_get_screen: assertion
`ScreenCount (GDK_DISPLAY_X11 (display)->xdisplay) > screen_num' failed

(magnifier:19579): Gdk-CRITICAL **: gdk_screen_get_root_window:
assertion `GDK_IS_SCREEN (screen)' failed

(magnifier:19579): Gdk-CRITICAL **: gdk_display_get_screen: assertion
`ScreenCount (GDK_DISPLAY_X11 (display)->xdisplay) > screen_num' failed

(magnifier:19579): Gdk-CRITICAL **: gdk_screen_get_root_window:
assertion `GDK_IS_SCREEN (screen)' failed

(magnifier:19579): Gdk-CRITICAL **: gdk_display_get_screen: assertion
`ScreenCount (GDK_DISPLAY_X11 (display)->xdisplay) > screen_num' failed

(magnifier:19579): Gdk-CRITICAL **: gdk_screen_get_width: assertion
`GDK_IS_SCREEN (screen)' failed

(magnifier:19579): Gdk-CRITICAL **: gdk_display_get_screen: assertion
`ScreenCount (GDK_DISPLAY_X11 (display)->xdisplay) > screen_num' failed

(magnifier:19579): Gdk-CRITICAL **: gdk_screen_get_height: assertion
`GDK_IS_SCREEN (screen)' failed

(magnifier:19579): Gdk-CRITICAL **: gdk_display_get_screen: assertion
`ScreenCount (GDK_DISPLAY_X11 (display)->xdisplay) > screen_num' failed

(magnifier:19579): Gdk-CRITICAL **: gdk_screen_get_width: assertion
`GDK_IS_SCREEN (screen)' failed

(magnifier:19579): Gdk-CRITICAL **: gdk_display_get_screen: assertion
`ScreenCount (GDK_DISPLAY_X11 (display)->xdisplay) > screen_num' failed

(magnifier:19579): Gdk-CRITICAL **: gdk_screen_get_height: assertion
`GDK_IS_SCREEN (screen)' failed

(magnifier:19579): Gdk-CRITICAL **: gdk_display_get_screen: assertion
`ScreenCount (GDK_DISPLAY_X11 (display)->xdisplay) > screen_num' failed

(magnifier:19579): Gdk-CRITICAL **: gdk_screen_get_root_window:
assertion `GDK_IS_SCREEN (screen)' failed

(magnifier:19579): Gdk-CRITICAL **: gdk_display_get_screen: assertion
`ScreenCount (GDK_DISPLAY_X11 (display)->xdisplay) > screen_num' failed

(magnifier:19579): Gdk-CRITICAL **: gdk_screen_get_root_window:
assertion `GDK_IS_SCREEN (screen)' failed

(magnifier:19579): Gdk-WARNING **: gdkdrawable-x11.c:904 drawable is not
a pixmap or window
The program 'magnifier' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadDrawable (invalid Pixmap or Window parameter)'.
 (Details: serial 9 error_code 9 request_code 154 minor_code 1)
 (Note to programmers: normally, X errors are reported asynchronously;
  that is, you will receive the error a while after causing it.
  To debug your program, run it with the --sync command line
  option to change this behavior. You can then get a meaningful
  backtrace from your debugger if you break on the gdk_x_error() function.)

> If we can get the bonobo-activation-server to return the CORBA object 
> ID of a remote gnome-mag service (or hack some other mechanism for 
> getting the object ID), then a remote client (for instance, a remote 
> instance of gnopernicus) can talk to a local gnome-mag service through 
> the bonobo/CORBA IPC interface.
>
> Bill
>
> > This sort of case is probably more common in some corporate 
> > environments, but we are not sure just how important it will be in 
> > the future.