The Next Generation display numbers

"Beerse, Corné" cbeerse "at" hiscom.nl
Thu, 21 Mar 2002 13:57:13 +0000


> -----Original Message-----
> That 1-port-per display issue is one of the things that struck me as
> particularly inelegant when I first encountered VNC; without knowing
> anything about the technical details behind it, I am guessing 
> that it was
> motivated by some shortcut taken to simplify the original 
> implementation.
> Going one step further, it might be nice if the next 
> generation could also
> respond to HTTP queries on the same port by attempting to 
> serve an applet -
> assuming that would not introduce excessive complexity  or 
> security issues
> into the server side of the connection.

Should be not that hard to arange with some port mapping application: First
listen on the port. If a webbrowser is found, provide the webpage as on
5800, with the propper port defined. If a vcnviewer found, remap the port to
the vncserver port and off you go.

> 
> Is that a theoretical possibility? The client currently looks for a
> plain-text RFB version number being passed to it from the 
> server; I assume
> something analogous is done by the server when connecting to 
> a listen-only
> viewer.  Since HTTP connections already do text requests, a 
> plain connection
> attempt or one with a query keyword appended would seem to me 
> to be able to
> communicate sufficient information for the server to decide 
> what to do.
> 
> 
> ----- Original Message -----
> From: "Michael Ossmann" <michael.ossmann "at" alttech.com>
> To: <vnc-list "at" uk.research.att.com>
> Sent: Wednesday, 2002-03-20 11:51
> Subject: Re: The Next Generation display numbers
> 
> 
> : On Wed, Mar 20, 2002 at 10:38:40AM -0500, Grant McDorman wrote:
> : >
> : > The problem is that VNC, on *nix systems, will always use 
> a display
> : > number for access by applications. If one drops the 
> display number for
> : > the VNC client connections, then we'll have *two* 
> unrelated IDs for
> : > the VNC server - the display number, and the VNC ID, whatever that
> : > might be (port perhaps?).
> :
> : We already have that.  A typical Xvnc listens for X apps on 
> :1 and also
> : listens for VNC clients on :1, where :1 and :1 are two completely
> : different things.  :-/
> :
> : It's even possible, though rare, to have Xvnc use 
> completely different
> : display numbers for X and RFB, which could be incredibly 
> confusing to
> : someone who doesn't understand the difference between :1 
> and :1.  And
> : the system breaks down completely if you have 100+ displays.
> :
> : It would be a lot less confusing if all VNC implementations used a
> : single port for RFB.  Xvnc would still have an X display number, but
> : anyone using X can be expected to figure that out.
> :
> : The current system only makes good sense on one platform, 
> and it doesn't
> : scale.
> :
> : > I agree it doesn't make much sense in the Windows-only 
> world; however,
> : > when connecting to *nix systems (from any system) it does 
> make sense,
> : > and (in my opinion) should not be removed.
> :
> : In a VNC implementation with a single port serving multiple 
> displays,
> : each display would still need some kind of identifier, and 
> it would make
> : sense for Xvnc to continue to use the X display number for 
> that purpose.
> : It would even work with display numbers > 99, which would 
> be refreshing.
> :
> : > Perhaps what we need is a way to explicitly specify the 
> VNC port (the
> : > 580x/590x) on both the client and server. Connections to non-*nix
> : > systems could then use that.
> :
> : That would be nice too.  Xvnc currently has command line 
> options with
> : which you can specify either port number or display number. 
>  It would be
> : nice if other implementations had that feature as well.
> :
> : --
> : Mike Ossmann, Tarantella/UNIX Engineer/Instructor
> : Alternative Technology, Inc.  http://www.alttech.com/
> : 
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