[sugar] olpc-games osc protocol

[Simon McVittie]

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On Mon, 11 Jun 2007 at 13:06:16 +0200, Simon Schamijer wrote:
> memosono is using the osc protocol 
> (http://opensoundcontrol.org/spec-1_0) to communicate with the game 
> server and to talk to the csound server. I think it is an easy to use 
> protocol and maybe some other games or activities want to use it as well.

This protocol seems to be rather like D-Bus, but different. We're using
D-Bus as the basis for most OLPC things - is there a compelling reason
not to here?

In the Telepathy-based collaboration framework Collabora are developing for
the OLPC (including the Presence Service), activities are shared over
"tubes". These can currently transport a distributed D-Bus over reliable
streams, with work in progress to do TCP-like reliable streams between
peers too. Transporting UDP-like datagrams over tubes, using ICE or
Jingle for NAT traversal, is a future enhancement.

The advantage of using Tubes is that we're already thinking about issues
which prevent peer-to-peer networks from working in practice, mainly NAT
traversal. Tubes provide a consistent API which will remain consistent
and transparent as we add additional NAT traversal methods and transport
mechanisms; the API is also consistent between the server-based and
link-local collaboration, and any future collaboration mechanisms. We will
also transport instant messages related to an activity, and the necessary
metadata to support the Buddy- and Activity-centric programming model used
in Sugar.

I've only looked at the OSC spec briefly, but you seem to be assuming
synchronized real-time clocks. Is this a requirement we can impose on XOs?
If it *is*, we could use it for the link-local communication to provide
additional ordering guarantees; but I suspect it isn't something we can
assume.

	Simon
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