DIFAX Source

We (Scripps Inst of Oceanography) use DIFAX, but do not get it from Alden.  We 
are a customer of Unisys.  This message is NOT an endorsement of Unisys.  We 
have our own, if different, set of problems with Unisys.  However, the system 
is usually reliable.

We pay Unisys $300.00 per year (ie, $25.00 per month, once per year) for the service.  There are 
three major problems.  First, this is a "pull" technology system.  My old friend 
"cron" ftp's to Kennett Square once an hour (about 5 minutes past) to get the maps for 
the previous hour.  Not an elegant solution, but it works.

The second problem has to do with reliability.  The the maps are produced on 
some other machine and transferred to the ftp host.  Frequency of transfer is 
unknown.  The problem is that this transfer is periodically shutdown (or fails) 
and they forget to restart it.

The third problem is format.  The maps are created as "pcx" format files.  They 
can be fairly large.  The latest 00Z chart is about 340K.  The latest western tropical 
surface chart is about 600K.  When I print these files on my 11x17 inch printer, I get 
large, crisp, clear maps.

These files would be a lot smaller, with no loss of detail, if they were in 
"gif" format.  They don't seem to be in any hurry to make this change.  
Remember, Unisys is the patent holder for the compression algorithm in gif.  Seems 
strange.  My connect time (and their consequent cpu time) on their ftp host would be much 
shorter with gif files.

One plus is that their trouble desk is manned 24/7 and I've never called there 
and not spoken with a real human being.  They don't always know how to solve 
problems (or have authority to solve problems), but they can usually contact 
someone who does.  Usually.

Finally, I have had conversations with Mike Porrecha (sp?) who indicated (but 
did NOT promise) that when the NWS shuts DIFAX down, Unisys might continue to 
produce the maps.

This is all "for what it's worth".  I think that, if a bunch of Unidata folks 
transferred their allegiance to Unisys and all started pulling maps down, their system 
would probably choke.  But, it might be a short term solution for some of you.