Fedora calls Akubra, saying "get me this datastream with this ID".
The datastream ID will be of the form "info:fedora/<pid namespace>:<pid >/<DSID>/<DSID>.<VERSION>" For example: "info:fedora/demo:MyObject1/JPEG/JPEG.0" Akubra then takes that string, hashes it, and looks in the corresponding directory as determined from the first characters of the hash to retrieve the datastream. In the case of datastreams, the root directory will be the datastreams directory you defined in fedora.fcfg. As others have pointed out, under ideal circumstances, you should never need to know nor care where Fedora is storing its objects and datatstreams. Occasionally, however, you might run into a situation where a file has become corrupted, or you need to do a selective low-level restore, in which case it is useful to know where the object is stored on the filesystem. I can also imagine certain use cases where you may want to get certain bits of information about large numbers of files very rapidly, in which case it may make more sense to go directly against the objects on the filesystem than through Fedora APIs. In my mind, Fedora is a layer on top of the digital objects; it provides some very nice functions and utilities and layers of abstractions, but my digital content -- the meat of my collection -- is those files stored on disk. As such, I like to know where they are, and how they're stored. I would be VERY hesitant to modify any of the files directly, however. But I could imagine copying them elsewhere to do unFedora things to them. -- Scott Riccardo Valzorio wrote: > Thanks for answers. > > I'm not going to "touch" that files, I was just wondering why... :) > > Tell me if I'm wrong, when I call : > > https://xxxxxx:8443/fedora/objects/PID/datastreams/DSID/content > > Fedora is reading DSID, calculating hash and "building" the path to get the > object? > > 1. hash(DSID) = aa.... > 2. ""get"" /var/fedora/data/datastreamStore/aa/DSID > > Thanks > > Rik > > > On 26/ott/2010, at 15.40, aj...@virginia.edu wrote: > >> I hope the Fedora core team will correct me if I'm misspeaking here, but my >> understanding is a major part of the intention of Akubra development is >> precisely to decouple low-level storage even further from Fedora's >> high-level interfaces. So "going behind Fedora's back" to get access to the >> low-level datastore may not be a good architectural pattern to implement. We >> (UVa) have usually found it to create more problems than it solves, because >> when we do that, we aren't letting Fedora do its job as a repository. >> >> Perhaps you might explain a little more about your use case or need and we >> can investigate whether your workflow can be accomplished using the >> high-level APIs? >> >> --- >> A. Soroka >> Digital Research and Scholarship R & D >> the University of Virginia Library >> >> >> >> On Oct 26, 2010, at 9:31 AM, Scott Prater wrote: >> >>> Riccardo, >>> >>> Akubra hashes the filename, then stores the object in a directory >>> structure based on the first characters of the hashes. The file >>> $FEDORA_HOME/server/config/akubra-llstore.xml contains the parameters >>> that determine how many of the hash characters are used, and how they >>> are divided up into directories. >>> >>> See >>> https://wiki.duraspace.org/display/FCR30/Configuring+Low+Level+Storage >>> for more information. >>> >>> -- Scott >>> >>> >>> Riccardo Valzorio wrote: >>>> Hi all, >>>> >>>> I have a question about the association between PIDs and ingested object' >>>> path. >>>> >>>> 1. In FC 3.3 (without Akubra) I can see a table named objectpaths >>>> containing: >>>> >>>> 246 | 1023:0 | /var/fedora-unipos/data/objects/2010/0211/14/31/1023_0 >>>> >>>> 2. In FC 3.4 (with Akubra) I see that table without any value. >>>> >>>> >>>> Where I can find the path where object have been stored ? >>>> >>>> Thanks >>>> >>>> Rik >>>> >>>> --- >>>> Riccardo Valzorio >>>> >>>> C.I.L.E.A. >>>> Sezione Gestione Sistemi >>>> >>>> Tel: 02 26995384 >>>> Mail: valzo...@cilea.it >>>> >>>> "A computer is like air conditioning: it becomes useless when you open >>>> windows." L. Torvalds >>>> >>>> GPG Key Fingeprint: BD93 74F3 42E6 B99C D9A1 7202 ABE6 8304 6F9C 18B0 >>>> >>>> >>>> >>>> >>>> ------------------------------------------------------------------------ >>>> >>>> ------------------------------------------------------------------------------ >>>> Nokia and AT&T present the 2010 Calling All Innovators-North America >>>> contest >>>> Create new apps & games for the Nokia N8 for consumers in U.S. and Canada >>>> $10 million total in prizes - $4M cash, 500 devices, nearly $6M in >>>> marketing >>>> Develop with Nokia Qt SDK, Web Runtime, or Java and Publish to Ovi Store >>>> http://p.sf.net/sfu/nokia-dev2dev >>>> >>>> >>>> ------------------------------------------------------------------------ >>>> >>>> _______________________________________________ >>>> Fedora-commons-users mailing list >>>> Fedora-commons-users@lists.sourceforge.net >>>> https://lists.sourceforge.net/lists/listinfo/fedora-commons-users >>> >>> -- >>> Scott Prater >>> Library, Instructional, and Research Applications (LIRA) >>> Division of Information Technology (DoIT) >>> University of Wisconsin - Madison >>> pra...@wisc.edu >>> >>> ------------------------------------------------------------------------------ >>> Nokia and AT&T present the 2010 Calling All Innovators-North America contest >>> Create new apps & games for the Nokia N8 for consumers in U.S. and Canada >>> $10 million total in prizes - $4M cash, 500 devices, nearly $6M in marketing >>> Develop with Nokia Qt SDK, Web Runtime, or Java and Publish to Ovi Store >>> http://p.sf.net/sfu/nokia-dev2dev >>> _______________________________________________ >>> Fedora-commons-users mailing list >>> Fedora-commons-users@lists.sourceforge.net >>> https://lists.sourceforge.net/lists/listinfo/fedora-commons-users >> >> ------------------------------------------------------------------------------ >> Nokia and AT&T present the 2010 Calling All Innovators-North America contest >> Create new apps & games for the Nokia N8 for consumers in U.S. and Canada >> $10 million total in prizes - $4M cash, 500 devices, nearly $6M in marketing >> Develop with Nokia Qt SDK, Web Runtime, or Java and Publish to Ovi Store >> http://p.sf.net/sfu/nokia-dev2dev >> _______________________________________________ >> Fedora-commons-users mailing list >> Fedora-commons-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/fedora-commons-users > > > --- > Riccardo Valzorio > > C.I.L.E.A. > Sezione Gestione Sistemi > > Tel: 02 26995384 > Mail: valzo...@cilea.it > > "A computer is like air conditioning: it becomes useless when you open > windows." L. Torvalds > > GPG Key Fingeprint: BD93 74F3 42E6 B99C D9A1 7202 ABE6 8304 6F9C 18B0 > > > > ------------------------------------------------------------------------ > > ------------------------------------------------------------------------------ > Nokia and AT&T present the 2010 Calling All Innovators-North America contest > Create new apps & games for the Nokia N8 for consumers in U.S. and Canada > $10 million total in prizes - $4M cash, 500 devices, nearly $6M in marketing > Develop with Nokia Qt SDK, Web Runtime, or Java and Publish to Ovi Store > http://p.sf.net/sfu/nokia-dev2dev > > > ------------------------------------------------------------------------ > > _______________________________________________ > Fedora-commons-users mailing list > Fedora-commons-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/fedora-commons-users -- Scott Prater Library, Instructional, and Research Applications (LIRA) Division of Information Technology (DoIT) University of Wisconsin - Madison pra...@wisc.edu ------------------------------------------------------------------------------ Nokia and AT&T present the 2010 Calling All Innovators-North America contest Create new apps & games for the Nokia N8 for consumers in U.S. and Canada $10 million total in prizes - $4M cash, 500 devices, nearly $6M in marketing Develop with Nokia Qt SDK, Web Runtime, or Java and Publish to Ovi Store http://p.sf.net/sfu/nokia-dev2dev _______________________________________________ Fedora-commons-users mailing list Fedora-commons-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/fedora-commons-users
