Re: AW: SV: focus failure with x11 and Mac OS X 10.5
Re: AW: SV: focus failure with x11 and Mac OS X 10.5
- Subject: Re: AW: SV: focus failure with x11 and Mac OS X 10.5
- From: "Andrew J. Hesford" <email@hidden>
- Date: Thu, 29 Nov 2007 08:05:11 -0600
There's been some negativity on this list regarding Leopard and X11.
It's time another user chimes in to defend Apple's X11 and criticize
the broken applications that no longer work with Leopard!
On Nov 29, 2007, at 12:14 AM, Ambrose Li wrote:
Running xdmcp would be the opposite of bloat, since you not only
taking away the cpu time used for ssh tunnelling, you are also
offloading window management to the remote server.
1. This is kind of like saying, "You save the time traveled to the
store by brewing your own beer instead of buying it." The "CPU time
used for ssh tunneling" is offset by the additional network bandwidth
involved with transferring extra pixel data over the network. If you
have, for example, two 100x100 windows inside a 1000x1000 nested X
server, you are sending 50 times as many pixels as you would be
tunneling those two windows. Compound this with the fact that SSH
connections tend to be compressed, so you further widen the network
gap. Since CPU cycles are often over-abundant, and network bandwidth
is often a limited resource, this is not usually a good trade-off.
2. The CPU time for SSH tunneling is just offloaded into extra burden
on the remote system, which has the responsibility of rendering an
entire display for users. Since these remote systems tend to serve
multiple users, this issue is compounded.
3. Managing windows on the remote system splits the user experience in
half. Presently, if you have multiple X11 windows, you can Command-`
to switch between them, like switching between windows of any Mac
application. Moving a group of windows into one nested server means
you suddenly have to worry about different ways to switch between
windows... on the remote system.
4. The nested server is a big hassle if you want to run programs on
multiple systems, each of which demands an XDMCP connection. What if
you want to run 5 applications on 3 different systems? You've got to
wade through 3 windows that each keep you one-step removed from the
applications you want. XDMCP does not scale. This is the reason X11
was designed to be network-transparent, to avoid issues like this.
5. I'm not a professional administrator, but I administer machines for
my research group. XDMCP is a hassle. Pretty much every modern Unix
runs SSH out of the box, but XDMCP usually requires an extra step to
get everything working. Plus, you have to keep the firewall open for
that unsecured port. This fails entirely when your department also
firewalls the network, and you have no control over what is open or
closed. XDMCP won't work if you attempt to connect from home. Hence,
you need to tunnel anyway.
6. On systems like Gentoo or FreeBSD, you often need to build and
install extra software for this. The servers are for heavy
computation... I don't need them rendering things like window managers
and desktops. If people require an X application, I can just install
that and the supporting libraries, but leave off the server and
display manager. Let their computers take care of that junk!
XDMCP is a bad idea. Just like manually parsing DISPLAY is a bad idea.
Applications or systems that require XDMCP are fundamentally broken. I
know it pisses people off when things they need don't work, but this
is a time to complain loudly to the developer of the application or
administrator of the system. In the meantime, there are a few
workarounds for Leopard users.
--
Andrew J. Hesford <email@hidden>
Department of Electrical and Computer Engineering
University of Illinois at Urbana-Champaign
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