🚀 go-pugleaf

In article <1992Jul31.135338.4000@fnbc.com> lemson@fnbc.com (David Lemson)  
writes:
> In article <l7gad3INN11j@calvin.usc.edu> sutter@calvin.usc.edu (Carl  
> Sutter) writes:
> > I'd like a BackSpace module to go out and grab the hourly weather
> > maps available on the Internet.  Is such a beast already written, or  
is
> > anyone working on one?  If not I may attempt it.  Any info on this
> > (including good weather map ftp sites) would be greatly appreciated.
> One good place to ftp weather maps is vmd.cso.uiuc.edu:/WX.  Format of  
the  
> name is CV073113.GIF for date 07/31 at 13Z.  Also CI and SA are other  
> prefixes, there are different views available.  
> 
> --
> David Lemson                                           (312) 732-4741
> FNBC Sys Admin (Summer) UIUC NeXT Campus Consultant(rest of the time)
> E-mail to: lemson@fnbc.com                          NeXTMail accepted

Whoa! As great an idea as this is, picture this for a second... 10,000 
NeXT machines, all with a PD package that automatically retrieves weather  
maps at HOURLY intervals from vmd.cso.uiuc.edu???  I don't think so.  At  
least not for long.

Having already worked out the automatic retrieval from this site once upon  
a time for our local group, let me throw some suggestions out on the table  
(the vmd.cso.uiuc.edu site has changed it's format since I wrote the code,  
BTW, so the code no longer works).

Anyway...

- First, set up a few designated host machines that retrieve the images  
from vmd.cso.uiuc.edu at hourly intervals, convert them to TIFF format,  
and then distribute them to as many machines as would be willing to host a  
weather image database.  This has several advantages.  Primarily, it  
avoids bogging the vmd.cso.uiuc.edu site down (or other sites; new sites  
can be added as needed).   Also, the retrieval and conversion of images is  
done at a few central machines and can be changed easily... Necessary  
because the vmd.cso.uiuc.edu site is sporadic and changes  
filename/directory names from time to time!

- Second, set the backspace module up so that it can get these images from  
any of the new host sites (Hey, they're already in TIFF format and the  
local machines don't have to do any processing to convert them!).  We  
might even think about a protocol where a host site can redirect requests  
to other hosts if it is down, getting too much of a load, hasn't received  
images, whatever...

- Now, a couple of suggestions on how to handle the actual data itself.   
When we were receiving data, I created two separate products... a full  
size version for setting as the background, and a sub-sampled version for  
doing animations of the past few days of weather (both are well worth  
having BTW).  Also, the products were RGB TIFFs with the visible weather  
data in the green band, and the infra-red weather data in the blue...  
makes for a pretty spiffy looking image.

- One other thing:  When this utility gets implemented, my guess is that  
it will become REAL popular (a "desktop weather station"!) and eventually  
add multi-GBytes of data, daily, to the overall network load (and not just  
during "off-hours")... It would be nice if this could be done in as  
painless a way as possible.  This may mean yanking the "hourly" retrieval  
feature from the Backspace module, and just having it updated when  
requested...  or grabbing the last day's worth of data only during  
off-hours... or grabbing only subsampled images... or... or ...or

My two cents worth...

Robert Kieffer
kieffer@spf.trw.com