Re: [ldm-users] Duplicate Products

Dave's implementation removes the EMWIN header (I hope). However, I was swamped yesterday and I tasked this one out. I didn't test it. If there's an issue, it's mine.
Stripping extraneous linefeeds is pretty trivial. There's nothing to 
prevent doing that and then doing a pqinsert, if we have to.
And... I understand the issues of working with the TOC and the 
constraints they have to work under.
gc

daryl herzmann wrote:
On Thu, 16 Dec 2010, Gerry Creager wrote:

I'll try to figure out what we did wrong here. We're snagging the same EMWIN feed Gilbert is, but could have fumble-fingered something, since I'm still short of calibrated fingers since shoulder surgery...
Unfortunately, one can not seamlessly plex together the 
EMWIN/WeatherWire with the NOAAPORT/SBN dataset using baseline 
software.  I forget which system does it, but one of them arbitrarily 
tacks on an extra DOS line feed to every product, thus LDM sees the same 
product twice, since the line feeds are used to compute the product 
checksums.
For NWSChat, I get a direct socket feed from the Gateway/TOC that 
contains the plexing of, I think, 4 different internal NWS systems.  
This feed has duplicates all day long.  So when Gilbert was hoping for a 
direct backup IDD feed from the TOC, this problem would have caused lots 
of pain for others...  Anyway, I ended up writing a pre-conditioner to 
my decoders that striped extraneous line feeds and computed product 
checksums that way.  This works for 99% of the products, but there are a 
few more products that have extra control characters inserted (namely 
from SPC) into the non SBN feeds.
My impression is that the private sector weather folks have been dealing 
with this issue for a very long time and it has been frustrating for 
them. I've been bugging the TOC/Gateway folks about it, but they are 
extremely short of resources and dealing with ancient IBM computer 
systems.  This issue is on their TODO list though.
I wish LDM had an option to arbitrarily strip trailing line feeds before 
checksum computation.  Before somebody says this would be a performance 
killer, it isn't. :)
daryl

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