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[IDD #GCZ-446166]: IDD for the rest of us?



Hi Kelly,

re:
> Thanks for the quick response!

No worries.

> Here are the answers to your questions...
> 
re: What data are you looking to get access to?

> Primarily to start I'm looking for the NEXRAD Level III (or II,
> whichever is available) and IR/VIS imagery from the GOES satellites.

OK.  The Level III NEXRAD products and GOES image sectors are all available
in NOAAPORT.

> I've found these available on the UCAR ADDE servers and they meet my
> needs.  What I'm stumbling over is trying to keep content updated in a
> clean manner with low overhead on my part and on the servers part.

OK.  It is true that the IDD way of getting data is "better" for delivering
only what is new.

> My
> impression of the IDD was that when new data came in it was 'pushed'
> out the clients

Yes.  The way the LDM/IDD works is the downstream registers a request(s)
for data via a regular expression for the product ID, and data that
matches that request(s) is pushed to the requester when it becomes
available.

> and they were stored locally on disk, am I correct on
> this?

Processing of the data in the LDM context is very flexible.  Storing the
data to disk is one of a myriad of possibilites.  It is up to the
end user to decide what s/he wants to do with the products that are
received.

> If so then that is really what I'd like to do and would cut down
> on useless time querying files to see if they've been updated or not.

Very true.  It is much more efficient to have the desired data pushed
to the end user when it becomes available.  This gets rid of all of
the overhead encumbered by polling.

re: What application are you using to access data through ADDE servers?
> 
> Previously I've used GEMPAK to display data (NIDS) in a graphical format
> from raw data that was downloaded from the TGFTP at the NWS.  I wrote a
> perl script that checked the dates of the files and compared them to
> the last downloaded date adn that worked swell except for their network
> connection often times was lagged or the site would go down for several
> hours which proved to be unreliable.

OK, this is the typically polling kind of setup.

> Now I'm using McIDAS-X in a
> command-line script using 'mcenv' to download the data from the ADDE
> servers.  Like I said... it works great but I really would like to pull
> the data down continuously and store it locally onsite instead of having
> to download a file not knowing if its been updated each time.

The nice thing about McIDAS is that you can indicate that you want
to transfer data _if_ it is newer than what you already have.  You should
checkout the OVERride= keyword on IMGCOPY.  Here is a snippit from the
online help for IMGCOPY that talks about OVERride=:

   OVERride=NO  | does not copy image if most recent image in ddataset
                  contains same date, time and band (def)
           =YES | copies image to ddataset position following the most
                  recent image even if the date, time and band are same;
                  this keyword is ignored if a position number is
                  specified in ddataset

re: Finally, what is your status (e.g., home enthusiast; private business; 
etc.)?

> Right now I would say 'home enthusiast' fits me the best.  I've been
> trying to find ways to script product generation for the general public
> and eventually display it on the web.  This is not something I intend to
> ever make money off of, just merely a hobby of mine.  I'm a software
> developer by day so this is a way to expand my horizons in my off time
> and expand my weather interests.

Where did you get McIDAS?  Unidata licensed to distribute McIDAS to educational
institutions worldwide, not individuals.  Our license allows us to distribute
McIDAS to other entities (including individuals) on a case-by-case basis.

> Thanks!

No worries.

Cheers,

Tom
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Ticket Details
===================
Ticket ID: GCZ-446166
Department: Support IDD
Priority: Normal
Status: Closed


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