Hi All, Something in the back of my mind from a project in which I have peripheral engagement (so may be a red herring or worse). Didn't Argo put a lot of effort into a NetCDF history encoding for their format?
Cheers, Roy. ________________________________________ From: cf-metadata-boun...@cgd.ucar.edu [cf-metadata-boun...@cgd.ucar.edu] On Behalf Of Nan Galbraith [ngalbra...@whoi.edu] Sent: 06 September 2011 13:46 To: CF list Subject: Re: [CF-metadata] Branching "history" Hi 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? I'm not sure how many existing practices there are, but a new syntax is *definitely* preferable to loss of this information. The standard lets you continuously append processing 'events' to the global history, using a timestamp; in theory you can append all the branching histories, adding information about which component was modified (maybe going from datestamp/action to datestamp/component/action ?). The component identifiers would need to include enough information to let the user know what slice, and what variable, was modified by each action. John's SSDS example shows an interesting way to accumulate this information, which could be expanded for branched provenance. It's not quite the same as the NetCDF-defined history attribute, but it looks like a great way to make this field machine readable. By the way, here's the definition, from the NetCDF Users' Guide: > history > > A global attribute for an audit trail. This is a character array with > a line for each invocation of a program that has modified the > dataset. Well-behaved generic netCDF applications should append a > line containing: date, time of day, user name, program name and > command arguments. and a snippet from the CF standard: > 2.6.2. Description of file contents > > The NUG defines title and history to be global attributes. We wish > to allow the newly defined attributes, i.e., institution, source, > references, and comment, to be either global or assigned to > individual variables. When an attribute appears both globally and as > a variable attribute, the variable's version has precedence. ... > > history > > Provides an audit trail for modifications to the original data. > Well-behaved generic netCDF filters will automatically append their > name and the parameters with which they were invoked to the global > history attribute of an input netCDF file. We recommend that each > line begin with a timestamp indicating the date and time of day that > the program was executed. - Nan _______________________________________________ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata-- This message (and any attachments) is for the recipient only. NERC is subject to the Freedom of Information Act 2000 and the contents of this email and any reply you make may be disclosed by NERC unless it is exempt from release under the Act. Any material supplied to NERC may be stored in an electronic records management system. _______________________________________________ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata