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[LDM #PYO-163672]: Want to find out more about LDM

This archive contains answers to questions sent to Unidata support through mid-2025. Note that the archive is no longer being updated. We provide the archive for reference; many of the answers presented here remain technically correct, even if somewhat outdated. For the most up-to-date information on the use of NSF Unidata software and data services, please consult the Software Documentation first.

  • Subject: [LDM #PYO-163672]: Want to find out more about LDM
  • Date: Mon, 14 Oct 2013 13:41:00 -0600
Thomas,

> How does the user access data serve under LDM (HTTP/FTP/etc)?

A user who wishes to subscribe to certain data-products adds a REQUEST entry to 
their LDM configuration-file. The entry specifies the upstream host and the 
desired data-products.

> If I have a collection of NETCDF observational data, what do I need to do
> to get it ingested into LDM.  As an active archive, we need to keep
> ingesting the latest archived data into LDM.  Ingestion usually takes
> time.  Could LDM able to overlay on top of existing (readonly) file system
> and process the NETCDF there?  Does it maintain its own cache or archive?

Data-products are "injected" into an LDM distribution system by inserting them 
into an LDM product-queue (which, typically, holds about one hour's worth of 
data). From there, the data-products are distributed according to the topology 
of the LDM network as determined by the individual REQUEST entries. The LDM 
package contains a program (pqinsert) that converts files into data-products 
and inserts them into the product-queue.

> Sorry for all the questions.  I am poking through your documentation site
> and it is not very clear.  If you have existing tutorial material to get
> met start, it will be greatly appreciated.

Well, you could try the LDM tutorial at 
<http://www.unidata.ucar.edu/software/ldm/ldm-current/tutorial/index.html>. I'm 
afraid it's not very good but it's a start. Feel free to ask me questions.

> Thanks,
> 
> Thomas.
> 
> --
> Thomas Huang
> Jet Propulsion Laboratory
> 4800 Oak Grove Drive, Mail Stop 171-264, Pasadena, CA 91109
> Phone: 818.354.2747, Email: address@hidden
> 
> DISCLAIMER: All personal and professional opinions presented herein are my
> own and do not, in any way, represent the opinion or policy of JPL, NASA
> or Caltech.

Regards,
Steve Emmerson

Ticket Details
===================
Ticket ID: PYO-163672
Department: Support LDM
Priority: Normal
Status: Closed