Re: 20051220: NcML Aggregation in THREDDS

• To: Bjørge Solli <bjorge.solli@xxxxxxxx>
• Subject: Re: 20051220: NcML Aggregation in THREDDS
• From: John Caron <caron@xxxxxxxxxxxxxxxx>
• Date: Thu, 12 Jan 2006 14:58:50 -0700

Bjørge Solli wrote:

On Tuesday 10 January 2006 02:19, you(John Caron) wrote:

Bjørge Solli wrote:

Hi again John.

On Wednesday 21 December 2005 19:15, you(John Caron) wrote:

Bjørge Solli wrote:

John Caron wrote:

Unidata Support wrote:

------- Forwarded Message

To: support@xxxxxxxxxxxxxxxx
From: =?ISO-8859-1?Q?Bj=F8rge_Solli?= <bjorge.solli@xxxxxxxx>
Subject: NcML Aggregation in THREDDS
Organization: Nansen Environmental and Remote Sensing Center - Bergen
Keywords: 200512201217.jBKCH47s009594 THREDDS NcML aggregation

Hi,

I am currently rewriting our xml-files to use the new aggregation
functionality in Thredds 3.4. I have looked over all the
documentation I could find on thredds and NcML but still have one
unansvered Q. Hope you can help:

In the old version we used AggServer with an xml-statement like this:
...
<aggregation serviceName=".." aggType=".." varType=".." varUnit".."
dateFormat="yyyy/M/d:hh:mm:ss z">
 <fileAccess urlPath="long_name_b20030604_f200305289999.nc"
coord="2003/05/28:00:00:00 GMT" />
 ...
...

My remaining Q is where I should write dateFormat now. I have
something like this:
...
<variable name="time" type="int" shape="time">
 <attribute name="units" value=".." />
 <attribute name="_CoordinateAxisType" value="Time" />
</variable>

Here you are defining a time coordinate of dataType "int"

I see I omitted the units-value, it is "secs since 1970-01-01 00:00:00".
This is a value I don't think my research coworkers want to change since
I understand it is some standard in their field. The one in charge are
on holidays, so will have to wait till he's back for the definite
answer.

yes thats a udunit string, which thredds also uses.
but if you use this, then you must write the correct integer values in
the coord field.

<aggregation dimName="time" type="joinNew">
 <variableAgg name="T" />
 netcdf location="long_name_b20030604_f200305289999.nc"
coord=""2003/05/28:00:00:00 GMT" />

But you are giving it String values.

I guess I could give it int-values, but that would remove readability.

true, so the ISO 8601 date strings would work better.

I tried with strings, but failed, and now I try with int, like this:

I have enclosed a full xml-file, but here is how it looks now:
...
<dataset name="MERSEA CLASS 1 Aggregated files">
 <service name="this" serviceType="OpenDAP" base="" />
 <service name="TOPAZ" serviceType="OpenDAP" base="/thredds/dodsC/">
  <datasetRoot path="topaz"
dirLocation="http://nerscweb.bccs.uib.no/nersc/nph-dods/mersea-ip/nat/mer
sea-class1/" /> </service>
 <metadata inherited="true">
  <serviceName>this</serviceName>
  <dataType>Grid</dataType>
 </metadata>
 <dataset name="Best estimate - Atlantic"
ID="mersea-ip-topaz-class1-nat-be"
urlPath="topaz/mersea-ip-topaz-class1-nat-be">
  <serviceName>TOPAZ</serviceName>
  <netcdf
xmlns="http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2";>
<dimension name="time" length="0" />
   <variable name="time" type="int" shape="time">
    <attribute name="units" value="secs since 1970-01-01 00:00:00" />
    <attribute name="_CoordinateAxisType" value="time" />
   </variable>
   <aggregation dimName="time" type="JoinNew">
    <netcdf
location="http://nerscweb.bccs.uib.no/nersc/nph-dods/mersea-ip/nat/mersea
-class1//topaz_V2_mersea_nat_grid1to8_da_class1_b20050706_f200506299999.nc
" coord="1120003200" />
...

ok, now i see it, "coord" should be "coordValue"

not sure why im not giving a validation message, but I think its because I dont 
parse the NcML until its requested. ill try to get that working.

I use ant also to redeploy, its a nice way to do it.