Again, I have to preface my reply by welcoming correction (if it is needed), but I think you are almost right.
It is _Fedora_ that is doing more or less what you describe as the hashing (although I'm not very sure of the details of the hashing, having never yet needed to adjust them) but it is _Akubra_ that is retrieving the actual contents (blob) and handing the results back to Fedora. You might want to look at the Akubra API, which makes clear that Fedora itself, when running over Akubra, never bothers much more about low-level storage (once having configured it) than to know that it can hand a blob of data and an URI to Akubra and expect to get back that blob when it asks for it by that URI. That's why the config file to which Scott directed your attention is referring to so many Akubra classes (e.g. "org.akubraproject.fs.FSBlobStore"). In theory, you could remote your Akubra storage (in something of the way that many institutions have remoted their Resource Indexes or JMS message brokers, for scaling). I don't know if that is yet a common practice or ever will be. It's also why, if some group wants to implement a new kind of low-level store, e.g. a replacement for the semi-deprecated Amazon S3 low-level store, they will be concerned primarily with Akubra and not with Fedora. --- A. Soroka Digital Research and Scholarship R & D the University of Virginia Library On Oct 26, 2010, at 10:47 AM, 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, [email protected] 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: [email protected] >>>> >>>> "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 >>>> [email protected] >>>> 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 >>> [email protected] >>> >>> ------------------------------------------------------------------------------ >>> 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 >>> [email protected] >>> 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 >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/fedora-commons-users > > > --- > Riccardo Valzorio > > C.I.L.E.A. > Sezione Gestione Sistemi > > Tel: 02 26995384 > Mail: [email protected] > > "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 > [email protected] > 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 [email protected] https://lists.sourceforge.net/lists/listinfo/fedora-commons-users
