Curt, WE7U wrote:
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.
CAVEAT: I can't even START to think about this 'til I can extricate
myself from a particular project, but what I'd like to see would be some
variant on this...
Imagine a site with a CONUS map (to start, and thinking small; we could
scale up) where you can use a bounding box to identify your region of
interest or cursor to select a particular point (map). After that
selection you see an inventory of different maps and types of maps
available, and you use a check-list to identify the ones you want. The
site prepares a separate page/Torrent stream to provide these, and the
page is lightly persistent (days before it ages out) and indexed on a
page of recent selections.
You'd have the option of getting the data via download or Torrent at
that point. Simplified data delivery.
I'm not sure how making delivery of all those maps via Torrent can be
done without some form of simplified selection, but then I'm not a big
Torrent user. I tend to get OS distro's and kernel updates that way, at
home, because it "just happens" and I don't have to worry much about it.
This doesn't make me an expert, though, as I got it working once and
locked in the format.
gc
--
Gerry Creager -- [EMAIL PROTECTED]
Texas Mesonet -- AATLT, Texas A&M University
Cell: 979.229.5301 Office: 979.862.3982 FAX: 979.862.3983
Office: 1700 Research Parkway Ste 160, TAMU, College Station, TX 77843
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