[Dextrose] [Sugar-devel] [DESIGN] Extending activity microformat spec to include optional olpc_activity_size

Bernie Innocenti bernie at codewiz.org
Sun Nov 28 22:06:47 EST 2010

On Sun, 2010-11-28 at 23:03 +0000, Daniel Drake wrote:

> Activities are generally megabytes in size, or at least hundreds of
> kilobytes. This transfer would follow the size query.
> Your proposal would just shave off a handful of bytes.

If the size were only needed at download time, then there would be no
need to perform a separate query: the size is already present in
Content-Length header.

I think Anish wants to know the size beforehand to show it in the list
of update candidates.

> In my experience, even in OLPC deployments in wealthier nations, the
> latency on the internet connections (especially when split between
> hundreds of students in a school) is so high that its totally
> impractical to consider activities hosted on a remote server. Size
> querying or not, its just so painfully slow and unreliable.
The schoolserver could cache the xo bundles. In Paraguay, this wasn't
happening for the largest ones due to size limits in the default
configuration of Squid. So we increased the maximum size for .xo.

> The only viable option is to host the activities (and activity group)
> locally on the school server. And OLPC provides good infrastructure to
> do this, which is in use in various countries.

True, but distributing the bundles *to* the schoolservers is still on a
do-it-yourself basis, with rsync scripts, cronjobs, puppet and all the
associated complexity.

In the real world, most bundle downloads will probably come from sources
other than the deployment HQ. Think of Doom & Super Vampire Ninja Zero!
So the generic HTTP caching offered by squid is probably going to be a
better use of the school's bandwidth and disk space.

> If you're wanting to make efficiency improvements in activity
> updating, I would suggest tackling the bigger fish such as
> http://bugs.sugarlabs.org/ticket/1499

Oh! Yet another advanced feature we would have got for free by adopting
a real package format!

   // Bernie Innocenti - http://codewiz.org/
 \X/  Sugar Labs       - http://sugarlabs.org/

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