[hdf-forum] provenance

[Quincey Koziol]

Hi Matthew,

On Mar 24, 2009, at 2:15 AM, Dougherty, Matthew T. wrote:

> thanks, Werner.
>
> not sure what access time means, or the difference between  
> modification time and change time.
>

	A caveat before I explain these further: only the birth time is fully  
working and the modification time is only updated for certain dataset  
operations.  These fields were not fully finished before the 1.8.0  
release and we haven't had a chance to come back and flesh them out.

	Here's the time fields that are available in the object header, for  
each object in the file:
		Birth Time (btime) - When the object was created
		Access Time (atime) - When the object was last accessed (read or  
write)
		Modification Time (mtime) - When the object's raw data was last  
modified
		Change Time (ctime) - When the object's metadata was last modified

	These should correspond to the fields in the POSIX "stat" call ("man  
2 stat").  Also, currently the mtime field is tracking metadata  
modifications on datasets, but that's a bug and will be corrected when  
this feature is wrapped up.

	BTW, tracking these time for an object can be disabled by calling  
H5Pset_obj_track_times() with the 'track_times' parameter set to FALSE.

> I would guess the modified time is the latest, and previous times  
> are not kept.
>

	Yes, that's true.

		Quincey

> Matthew Dougherty
> 713-433-3849
> National Center for Macromolecular Imaging
> Baylor College of Medicine/Houston Texas USA
> = 
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> ======================================================================
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>
>
>
> -----Original Message-----
> From: Werner Benger [mailto:werner at cct.lsu.edu]
> Sent: Tue 3/24/2009 2:00 AM
> To: Dougherty, Matthew T.; hdf-forum at hdfgroup.org
> Subject: Re: [hdf-forum] provenance
>
> Each object in an HDF5 file should have its own "birth time, modified
> time, change
> time, access time":
>
> http://www.hdfgroup.org/HDF5/doc/RM/RM_H5O.html#Object-GetInfo
>
> Not sure how far this is stored in the file as well; I guess an  
> "access
> time"
> would not work well for a read-only file.
>
>         Werner
>
> On Tue, 24 Mar 2009 00:38:37 -0500, Dougherty, Matthew T.
> <matthewd at bcm.tmc.edu> wrote:
>
> > when an hdf file is created, are there any unique metadata  
> embedded into
> > the file, such as a date?
> >
> >
> >
> > Matthew Dougherty
> > 713-433-3849
> > National Center for Macromolecular Imaging
> > Baylor College of Medicine/Houston Texas USA
> >  
> = 
> = 
> = 
> ======================================================================
> >  
> = 
> = 
> = 
> ======================================================================
> >
> >
>
>
>
> --
> ___________________________________________________________________________
> Dr. Werner Benger <werner at cct.lsu.edu>               Visualization  
> Research
> Laboratory for Creative Arts and Technology (LCAT)
> Center for Computation & Technology at Louisiana State University  
> (CCT/LSU)
> 239 Johnston Hall, Baton Rouge, Louisiana 70803
> Tel.: +1 225 578 4809                        Fax.: +1 225 578-5362
>

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