Hi Richard,
We are considering similar questions for the OOI Cyberinfrastructure.
I am wondering why you say the history attribute is only intended to be human readable? (I'm not an expert on netCDF, so this may be a doofus question.) I couldn't find any language that says that, and some of the conventions suggest machine-readable is just fine, and I'd prefer a machine-readable history, so long as it's still human-readable.
In the COARDS profile
http://ferret.wrc.noaa.gov/noaa_coop/coop_cdf_profile.html
it says "Although not mandatory the attribute 'history' is recommended to record the evolution of the data contained within a netCDF file. Applications which process netCDF data can append their information to the history attribute."
In the netCDF Attribute Convention for Dataset Discovery,
http://www.unidata.ucar.edu/software/netcdf-java/formats/DataDiscoveryAttConvention.html
the history attribute is described as "Provides an audit trail for modifications to the original data."
And by example, I know that MBARI has a fairly complete history that they put in NetCDF files, for example see
http://dods.mbari.org/opendap/data/ssdsdata/deployments/m0/200701/OS_MBARI-M0_20070130_R_TS.nc.info
and
https://confluence.oceanobservatories.org/display/CIDev/Define+use+case+for+data+provenance
In the sample, this history is not contained in the history attribute, but in an attribute called ssds_provenance. I don't think that example is branched, but they may have some that are, and that format looks trivial to express branches to me. (And is both readable and machine-parseable, too. Kudos to Mike McCann and the MBARI team.)
If the MBARI syntax is parseable and there are not competing syntaxes, that would not be a bad proposal in my book.
Since people use all sorts of things for history, we might want the first line to specify the syntax/convention being used.
John
On Sep 5, 2011, at 05:38, Hattersley, Richard wrote:
> Dear all,
>
> Are there any existing practices (either established or experimental) for the use of the "history" attribute when dealing with complex, branching processing histories?
>
> Given the "history" attribute is only intended to be human readable, I suspect the answer is "no". In which case, what would be more palatable: inventing a new syntax, or throwing away everything prior to the last linear sequence?
>
>
> Richard Hattersley AVD Iris Technical Lead
> Met Office FitzRoy Road Exeter Devon EX1 3PB United Kingdom
> Tel: +44 (0)1392 885702 Fax: +44 (0)1392 885681
> Email: richard.hattersley at metoffice.gov.uk Website: www.metoffice.gov.uk
>
> _______________________________________________
> CF-metadata mailing list
> CF-metadata at cgd.ucar.edu
> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
John Graybeal <mailto:jgraybeal at ucsd.edu>
phone: 858-534-2162
Product Manager
Ocean Observatories Initiative Cyberinfrastructure Project:
http://ci.oceanobservatories.org
Marine Metadata Interoperability Project:
http://marinemetadata.org
Received on Mon Sep 05 2011 - 15:24:32 BST
