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Re: 20051220: NcML Aggregation in THREDDS

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


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" />

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/mersea-class1/"; />
<metadata inherited="true">
<dataset name="Best estimate - Atlantic" ID="mersea-ip-topaz-class1-nat-be" urlPath="topaz/mersea-ip-topaz-class1-nat-be">
<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" />
<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" />

But still I get 0 in all fields when I look at the http://barents.nersc.no:8080/thredds/dodsC/topaz/mersea-ip-topaz-class1-nat-be.ascii?time[0:1:1]
-> output:
Dataset {
Int32 time[time = 2];
} dodsC/topaz/mersea-ip-topaz-class1-nat-be;
0, 0

Hope you have time to give me some help on this.


Hi Bjørge:

I dont see anything wrong. Are there any diagnostic messages in the logs?

Have you restarted (or reinited) the server since you made changes?

Is your server public? It doesnt seem to be up at the moment.

Do you have remote management working? (see 

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