I participated in a 90 minute skype call with a group of people working in the OLPC Australia deployment; Srindhar Dhanapalan, Jerry Vonau, and Andrew van der Stock. I woke up early this morning, all excited, as I tried to process all the implications of our conversation.
Srindhar proposed a simplified, more focused, less complex vision for the XS. For him the essential service provided by the XS is ejabberd, and the collaboration facilitation it provides. He thinks that whatever is available on the XS must just work. The distances in Australia make it impossible for a sysadmin to visit each site and configure servers, networks, etc.
He proposed that the XS functions should just be selected by a set of check boxes available from the XO control panel. I would prefer it to be just another Sugar activity, perhaps not initially visible, similar to terminal and the log reader Activities. But that’s really a implementation detail.
Configuration of the network can use Avahi/bonjour multicast DNS mechanisms and implement service discovery techniques.
The XS would then be a set of RPMs, available on the internet, which would be selected by the teacher using this graphical control panel or Sugar Activity. If internet is not available, the XS RPMs, and indeed the whole RPM repository for the appropriate Fedora distribution, can be available on an 8 GB USB stick.
Should a school want to build up a heavy-duty high-power server, the appropriate Fedora install disks would be used to bring it to life. Then an XO, with this preinstalled graphical XS service selection interface would be used to add the XS functionality via ssh.
So with this service discovery approach, there could be somewhere in the school a backup server with a large disk. It would register students, and receive backups. Dhcp would be replaced by the mechanism of self assigned ip addresses in the 169.254.x.x range.
Internet access would be another service available on the network, but not necessarily from the local classroom XS, which is facilitating collaboration. In situations of low bandwidth, the internet portal machine needs a large disk for squid to keep its cache in.
With this sort of flat network, and a service discovery strategy, the XS that is local to the classroom might not even need a hard disk. I just checked Amazon, and found that a 32GB SD class 10 (10 mByte/sec) card costs $13.
This is all mediated by specially selected wifi AP hardware running special software that facilitates service discovery and minimizes congestion.