Re: 20051220: NcML Aggregation in THREDDS

Bjørge Solli wrote:
> Hi John,
>
> John Caron wrote:
>
> > Since you are explicitly writing the netcdf elements, we were 
> > expecting that you could write the correct values there without having 
> > to translate through a DateFormat. Is that not so? (see below also)
>
>
> I guess so, but usually I try to use already implemented ways instead of 
> doing a script on it myself. Less maintainence that way. So there is now 
> way of doing this in the current version?

nope, sorry

> > 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
> > >
> > >
> > >
> > >
> > > 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.

> > Do you have the ability to write ISO 8601 date strings? If so, I would 
> > change the type of the time coordinate to String and do that.
>
>
> Thanks for the advice, I will discuss it with my coworkers.
>
> > > Since I am not using the scan tag I cannot use the dateFormatMark 
> > > either (which would not work on this example anyway since the 
> > > filename is not the same in front of the #-mark, which would have to 
> > > be after the '_f').
> >
> >
> >
> > We will also add regular expression matcher for that case.
>
>
> Regexp is good! Is it possible to use it directly in the xml?
>
> BTW: I'm a programmer, not a researcher, so I don't think I fully 
> understand the implications a change like the one you suggested would have.
>
> Thankyou.
> Regards