Protocol Changes (was: Zoom / Scaling in VNC)

[Jens Wagner]

Brandon Ibach wrote:

> Quoting Jens Wagner <vnc "at" hexonet.de>:
> > Just a question, but what will you need a rfb-proxy for if it is not even
> > decoding the framebuffer  info? In this case a tcp forwarder will do even
> > better.
>
>    Not necessarily true.  The proxy I just described in my message of
> yesterday would not decode any updates, but would simply mediate
> update requests of all the clients and take the load of update
> distribution off of the server.

Didn't think of that case. My fault :-(

> > Let me give an example: Think of an toolkit (buttons...) which sits on top of
> > the rfb stream. This toolkit could create a workspace without any
> > buffering! (Would be important for many users + not so much RAM)...

> > ... If you need to know the size you will also need to buffer the whole update.
> In
> > this special case it's unacceptable.
> >
>    Yep, you're right, in that special case.  But how common is that?

Ever thought of embedded systems? Think of a network printer wich exports its display
using rfb. I could tell you more than a lot of such ideas but I won't :-)

> And what's to prevent a new version of the protocol creating an
> alternative update format that could be supported by a special case
> that doesn't want to specify a length?
>    As I said, there are issues both ways in including a length on
> every message.  More important is a modification to the basic protocol
> that will allow for the flexibility to have the choices.

Some servers could have a feature "sendFrameBufferUpdateLength" that's initially off.
The clients could turn it on then.
IMHO all the other messages have a fixed length or they have simple length fields.

>  Your
> extension idea is just a much a new protocol as my total redesign, and
> both are equally capable of maintaining compatibility with existing
> implementations.

So what about a list of new *optional* features?
- resize
- scale ( optional with antialiasing )
- packedpixels( 2 x 4 bit_per_pixel into 1 byte )
- zlibCompression
- jpegEncoding
- pngEncoding
- sendFramebufferUpdateLength
- ???

Jens



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