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Re: Problem solved

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  • Subject: Re: Problem solved
  • Date: Mon, 29 Sep 2003 18:18:29 -0600
Hi Youngsun,

Yes, feel free to ask me questions.  If I'm too busy I'll forward them
to someone else who can help you.

Yes, the LDM will send a product to a decoder.  Actually, it is the
pqact program that does this.  pqact will not send the product to the
decoder until the product has completely arrived, so you don't need to
worry about timing.  Also, it is not the case that the product will be
removed from the queue when completely processed.  The product will sit
in the queue until the space is needed for some other product.  The LDM
does track whether or not a product has been completely processed.  In
an earlier version a product marked as 'done' would be removed by a
separate program called pqexpire.  But, now the queue algorithms have
been rewritten and, rather than using pqexpire, space in the queue is
recycled as it is needed.

I'm not sure how your "storeAWS" decoder is written, but in order for
pqact to feed a product to a decoder, the decoder must be written to
read products from standard input (stdin).  If you want it to just
process one product (as opposed to waiting for products in a loop), it
should be coded to exit on "end of file".  (If your decoder must handle
lots of products you would code your decoder to receive products in a
loop.)

Referring to the EXP example I started with you last week, you pipe the
product to a decoder with a line in your pqact.conf like this::

EXP     .*      PIPE    <completePath>/storeAWS <program_arguments_can_go_here>


(Be sure to separate the fields with tabs.)  There are options to the
PIPE action - see the description of the PIPE action in the Site
Manager's Guide for more information.

I hope this gets you going.  Let me know if you have any further
questions, and I'm also interested in hearing how things turn out.

Anne


> Youngsun Jung wrote:
> 
> Hi Anne,
> May I ask you questions anytime if I have some?
> Then I think I don't need technical description because I have good 
> teacher(YOU ^^*).
> 
> I am thinking that LDM makes decoder run.
> Could you show me how I can run decoder named "storeAWS"?
> How can I setup pqact.config to run decoder right after product file has been 
> created?
> I don't want to run decoder before data transfer is completed.
> 
> LDM overview says that products removed from queue when completely processed.
> I've transfered one grid file like this:
> 
> pqinsert -vl - -f NGRID -p ko3_anal.2003092715 
> /home3/awips/data/fxa/Grid/KMA/raw/ko3_anal.2003092715
> 
> And I could see ko3_anal.2003092715 has been created in 
> /home3/awips/data/fxa/Grid/KMA/raw.
> But when I tried follows on upstream and downstream servers:
> 
> pqact -f NGRID
> 
> data still was in queue. I don't understand how it works...
> I understand you are so busy.
> Please answer me when you have time.
> 
> With my deep appreciation,
> Youngsun

-- 
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Anne Wilson                     UCAR Unidata Program            
address@hidden                 P.O. Box 3000
                                  Boulder, CO  80307
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