[sane-devel] SaneTwain and HP2200C

Henning Meier-Geinitz henning@meier-geinitz.de
Wed, 14 Aug 2002 17:04:53 +0200


On Wed, Aug 14, 2002 at 10:29:39AM +0100, Martyn Ranyard wrote:
>   b. (Good(tm) option) add to the network (and backend) protocol so that 
> when the backend is waiting for something, it can be pinged (in the IP 
> sense), to check it hasn't hanged.

There is a timeout of 3600 second on the server side so I guess the
shorter timeout comes from the client.

There was some disccussion about this topic some time ago, here is the
corresponding TODO list entry:

  - saned times out after 60 minutes. Check if the watchdog timer is
  really necessary (e.g. to avoid blocking scanners by one user).
  Maybe add a command line option to saned to set the timeout.
  Otherwise turn on TCP keep alive (where available) and (maybe) check
  the connection from server side.

I don't know too much about TCP programming and noone else has yet

> This probably involves lots of work, 
> but would mean that the front ends could give a better clue as to what is 
> happening - and maybe a status message could be passed (In this case "Lamp 
> warming up") so that the user knows that the program hasn't locked 
> up.  Because this would change the protocol, sanetwain would have to be 
> updated, and the network timeout would not be a problem (send ping packet, 
> recieve pong packet).

Better status messages are planned for SANE 2. Such changes can't be
done without a new standard.