Sequences, Lists, and Relational Constraint Expressions

[Steve Hankin]

Hi John,

This dilemma is the result of a mismatch between the "discipline 
neutral" generality of the OPeNDAP DAP and the relatively focussed data 
models that Unidata is working with.  The obvious way to address this is 
through conventions -- just as the CF conventions are already needed in 
order to map the generality of netCDF onto the Common Data Model.

It seems to me that the DAPPER conventions, if fleshed out, could 
address the problem that you pose.  Fully fleshed out DAPPER conventions 
would clarify the process for identifying the independent (coordinate) 
variables, georeferencing, the requirement (or not) for a 2-level 
Sequence, the scope of structures that would be permitted inside the 
sequences, the adoption (or not) of CF standard names, etc.   Through 
the conventions one could also impose restrictions (or convey 
information to clients) on the types of relational operations that are 
allowed and/or the variables to which they can be applied.

    - steve

=================================================

John Caron wrote:

> Hi James, et al:
>
> One problem I have in implementing opendap sequences is that you have 
> to support relational constraint expressions (RCE) on all of the 
> fields of a sequence. This only scales if you use a DBMS. I would 
> prefer to support RCE on some of the fields, eg the space and time 
> coordinates and station ids.
> Im wondering if anyone has this problem, and if there is anything to 
> do about it?
>

-- 
--

Steve Hankin, NOAA/PMEL -- Steven.C.Hankin at noaa.gov
7600 Sand Point Way NE, Seattle, WA 98115-0070
ph. (206) 526-6080, FAX (206) 526-6744