[sane-devel] SANE2 progress, eliminate data port

[astrand at cendio.se]

On Tue, 24 Oct 2006, Henning Meier-Geinitz wrote:

> On 2006-10-24 15:47, astrand at cendio.se wrote:
> > Hi. Can anyone explain the state of the SANE2 branch? I've noticed that 
> > the SANE2 development seems inactive. Is this branch discontinued?
> 
> The development of SANE2 hasn't begun, there have been only
> discussions and there is a draft of the SANE2 standard. The standard
> is not finished yet as some of the problems are not easy to solve. 

Ok, I'll stick to SANE1 for now, then. 


> > I will make a try to eliminate the separate data port requirement for 
> > "saned". I think it should be possible to do this by extending the SANE1 
> > protocol in a backwards compatible way, say, by introducing a new RPC 
> > call. Comments on this?
> 
> Possible problems: You can't cancel a scan while data acquisition is
> in progress. This is one of the adavantages of the 2 port solution.

I think cancel should be possible even without the separate port. TCP is 
bi-directional: You can send a cancel request to "saned" even though data 
flows in the other direction. 

It's true that most RPC servers (including saned, I guess) won't respond 
to new requests until the last one is finished, but my plan is not to 
transfer all data in one single call, but let the client do several calls, 
just like sane_read(). So, the client should be able to cancel the 
acquisition instead of calling the server for more data.

Regards, 
-- 
Peter Åstrand		ThinLinc Chief Developer
Cendio AB		http://www.cendio.se
Teknikringen 3
583 30 Linköping	Phone: +46-13-21 46 00