Re: [Xouvert-general] Network transparentcy and modules

[James Hoegl]

Tupshin Harper wrote:

> Jerry Westrick wrote:
>
> > Another insteresting topic for dicusion would be looking into better
> > support for VNC, which is what most people use instead of a remote
> > X-Server.
> What would be "better" vnc support? To me, vnc support is already 
> outstanding, and I use it frequently. However, it's paradigm is 
> substantially more limited than using X's networking support natively. 
> The ability to remotely run wm-unmanaged apps is wonderful, and vnc 
> will never support that kind of thing. In addition, vnc is inherently 
> bitmap based, and even with the various efficient compression 
> mechanisms that it uses, it is inherently suboptimal compared with a 
> protocol that understands more of the interface and event semantic 
> such as X(though X is far from being optimal itself).
>
> -Tupshin
>
>
>
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From a code based perspective, VNC would run slower on X if certian 
things were happening.
X, in itself, with its network transparency, is running on top of the 
kernel.
So, unless X has the ability to transmit via network code on its own, it 
has to allow for an extra step in the OSI layer.
Application/Presentation/Session/Transport - In a nutshell, the 
application sends information to the Unix protocol.
Unix protocol sends information to the nix kernel following the rest of 
the OSI layer, Network, Data-Link, and Physical

nix Kernel, then runs back up to Transport layer decoding all the 
information for the 3 layers, (each layer has encapsulation information, 
except for the Physical layer).
Then the nix Kernel initiates TCP, then IP protocols, selects the 
correct transmition device/protocol (er TCP/IP :) ), and sends it out.

Most network layers do not need to run up to the Transport layer, 
although it might in cases like switching from cat5 to fiber, etc.

This adds one extra hop, and increases CPU usage.

However, if VNC were to directly contact the kernel, this step would be 
skipped.

Although it does not look like much, it is. Especially if the Unix 
protocol used for the network transparency of X server is a limiting 
protocol, not fully utilizing the CPUs power/performance.

Im still looking into that last part ;)

James Hoegl
*nix wannabe