[Xastir] torrents and xastir

[Curt, WE7U]

On Fri, 1 Aug 2008, Jason KG4WSV wrote:

> ...I'm trying to understand if and how we (xastir
> and APRS users) can benefit from the distribution system in the
> sharing of our sometimes large chunks of data, like maps and VM
> images.
>
> The basic premise/assumption is that many people will want to download
> and many of those will make the data once they have downloaded, right?
> If no one peering, there is nothing to download?  I guess it degrades
> to a traditional master-client download if there's only 1 "peer".
>
> I'm trying to figure out if it's worth the effort, given our
> relatively small numbers, to make things like VM images, TIGER
> shapefiles, DRGs, DOQQs, etc available via bit torrent.

In the recent past I said I didn't know anything about torrent.
That was somewhat false, as I've been using it for a few years but
only in the "leecher" mode.  When it got to "seeding" I always shut
it down.  Now I see a reason to leave it in seeding mode and have
done so.  I basically understand how torrent works and am getting
used to some of the special lingo for it.

I don't yet know if the below scheme would work but I'll put it out
there.  Someone more familiar with it can shoot it down:

a) Someone runs a web page that has multiple ".torrent" files on it,
    representing all the things we have available to download.  This
    could be a Wiki page, right?  We'd have to be careful who has
    edit access to it (user/password).  We have one such page now
    with three items on it, but it's not a Wiki.  This web page ends
    up with very little usage as the bulk transfers happen
    client-to-client, not from this web page.

b) People make various maps available for download.  For instance I
    have three DVD's containing all of the USGS topos for WA that are
    freely distributable.  I also have a good portion of OR and a few
    for ID/MT/HI.  I'd love for these to be "out there" for other
    people to use.

c) These same people create a torrent file out of this data, upload
    it to the Wiki, and edit the Wiki to make that torrent link show
    up.

d) The first download ends up being a server/client relationship as
    you described, but if at least a few of the people doing the
    downloads leave their torrent client up and running, they become
    a shared resource for the same file.  More than likely if we put
    maps up there we'll have non-Xastir people doing downloads as
    well, maybe even becoming additional resources to download from.

e) The maps contributed in this manner must be freely distributable
    to preserve our good project name.

Questions I have still:

1) Would we want to create a torrent for each file?  For each CD or
    DVD set?  In my case the DVD's were created from a LOT of CD's,
    and each CD had a LOT of maps on it.  Of course each map is
    megabytes of data as well.  I know I could create a torrent for
    an entire directory, but in the case of the DATA and METADATA
    directories for these CD's or especially DVD's the download would
    be huge.  I guess once two people have it and are seeding it
    changes things, but that initial first download would take forever.

2) To make it easier on the map providers, one big download is the
    way to go.  To make it easier on the "leechers" it might be
    better to have smaller increments.  How does one decide this?
    I'm sure I could write a script that would make a torrent file
    out of each map file, but am not sure I could do the same to get
    the multiple thousands of torrents uploaded to a Wiki.

3) Is the idea of distributing maps via torrent workable at all?
    I've been looking for a method to make USGS DRG's and DOQQ's
    available for a number of years, and this seems the closest match
    to date.

-- 
Curt, WE7U.				archer at eskimo dot com
http://www.eskimo.com/~archer
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