[GRASS5] New IPC XDRIVER vs. fifo vs. UNIX Sockets???

[Bernhard Reiter]

Hi folks,
let me give my 0.02 Euro for what it is worth...


On Thu, Nov 16, 2000 at 10:16:07PM +0100, Andreas Lange wrote:
> All commands creating graphical output (d.rast, d.vect, d.sites etc.)
> use functions from the Raster library. The output of these calls are fed
> into a FIFO and read out by the DRIVER (XDRIVER for X Window output,

> FIFOs have the big advantage that they are an early invention in the
> history of unix systems and that they are standardized with POSIX.1. So
> nearly every unix has FIFOs.

I think this is correct. We should keep the FIFO option for portability.

> within Cygwin is that it is impossible for architectural reasons to
> create the server part of the FIFOs with Win9x/ME. I' am not shure if
> there is a FIFO implementation for Win NT, but the UWIN port (that sadly
> is not free in the GPL's sense) has the FIFOs. But excluding the
> Win9x/ME users is IMHO not acceptable.  

Windows NT has something called named pipes, which might server as fifos
or unix domain sockets. Windows based on DOS lacks theses, AFAIK.

> I think that the windows port is very important for the acceptance of
> GRASS. But on the other hand i think that it would be bad to change
> GRASS to something that causes much work and a lot of trouble _only_
> because Cygwin is missing something. 

I agree.

> At least we should check that there
> are no known problems/deficiencies with the Cygwin sockets or message

We shall keep the fifo option in any case. 
We can view the transport mechanism of the graphic drivers as a 
transport layer. And we can keep more that one method of
transportation. :)

A TCP based sockets port of the graphic transport layer seems to solve
the compatibility problems for Windows. I also suspect it to be slower
than the fifo, but it will work and as a side effect it might also work
over network connections. 

If there is enough interest somebody can add a named pipe implementation
for Windows NT later.... 

	Bernhard

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