There is no extra advantage, just different behaivours If you specify the actual checksum, fedora will get the file, and compute the checksum, and compare. If you do not specify the actual checksum, fedora will get the file, and compute the checksum, and store it.
Note, fedora will get the file each time the datastream is modified, and upon creation, to check the checksum. I tend to work with files in the 2 TB range, and those take a while to download.... Regards On Wed, 2011-01-26 at 12:53 +0100, Simon W Lamb wrote: > Thanks for the example Asger. Just for interest, I used the following:- > > > <foxml:datastream STATE="A" CONTROL_GROUP="M" VERSIONABLE="true" > ID="content"> > <foxml:datastreamVersion ID="content.0" LABEL="content" > MIMETYPE="application/pdf"> > <foxml:contentDigest TYPE="MD5"/> > .... > </foxml:datastreamVersion> > </foxml:datastream> > > Without the 'digest' specified, and Fedora auto computed the checksum. But I > do understand the extra advantages of adding your own DIGEST attribute > pre-ingest. > > Thanks again, > Simon > > -----Original Message----- > From: Asger Askov Blekinge [mailto:a...@statsbiblioteket.dk] > Sent: 26 January 2011 11:34 > To: Support and info exchange list for Fedora users. > Subject: Re: [fcrepo-user] Adding checksum to FOXML datastream > > The correct way is to write > > <foxml:datastream STATE="A" CONTROL_GROUP="M" VERSIONABLE="true" > ID="content"> > <foxml:datastreamVersion ID="content.0" LABEL="content" > MIMETYPE="application/pdf"> > <foxml:contentDigest TYPE="MD5" DIGEST="chkjshfkjsdk"/> > ... > > </foxml:datastreamVersion> > > </foxml:datastream> > > > Hope this helps > > > On Wed, 2011-01-26 at 11:41 +0100, Simon W Lamb wrote: > > Hi, > > > > > > > > I’m in the process of building a set of Fedora objects using FOXML. I > > have left the fedora.fcfg autoChecksum configuration set to False for > > performance reasons, however I would like to specify checksums on > > specific Datastreams. The Checksum documentation at > > https://wiki.duraspace.org/display/FCR30/Checksums hints that it > > should be possible to add checksum information at a Datastream level:- > > > > > > > > “Another way to override the default checksumming mechanism is via new > > attributes that have been added to the FOXML and METS specs for > > ingesting digital objects. The FOXML and METS specifications now allow > > the checksum algorithm to be used for each Datastream to be specified > > as attributes on one of the elements defining that Datastream. When a > > checksum algorithm is specified in the XML for a Datastream of a > > digital object, this value will be used to compute the checksum for > > that Datastream rather than the default algorithm specified in the > > fedora.fcfg file. Note that the syntax for thusly specifying a > > checksum algorithm for a Datastream in a digital object is different > > for FOXML and for METS, the specific syntax to use can be found in the > > schemas for those XML formats.” > > > > > > > > Therefore I have a built a FOXML with the following:- > > > > > > > > <foxml:datastream STATE="A" CONTROL_GROUP="M" VERSIONABLE="true" > > CHECKSUM="MD5" ID="content"> > > > > <foxml:datastreamVersion ID="content.0" LABEL="content" > > MIMETYPE="application/pdf"> ... > > > > </foxml:datastreamVersion> > > > > </foxml:datastream> > > > > > > > > Unfortunately this fails the schema validation (checksum not a valid > > attribute). Sure enough there is no mention of checksum at > > http://www.fedora.info/definitions/1/0/foxml1-1.xsd > > > > > > > > What is the correct way of specifying a checksum for datastream within > > FOXML? > > > > > > > > Many thanks, > > > > Simon Lamb > > Software Developer > > Information and Communication Technology Department (ICTD) || The > > University of Hull > > T. +44 (0) 1482 462076 > > s.l...@hull.ac.uk|| www.hull.ac.uk > > > > Customer Support. +44 (0) 1482 462010 || h...@hull.ac.uk || > > www.hull.ac.uk/help > > > > > > > > > > > > ------------------------------------------------------------------------------ > Special Offer-- Download ArcSight Logger for FREE (a $49 USD value)! > Finally, a world-class log management solution at an even better price-free! > Download using promo code Free_Logger_4_Dev2Dev. Offer expires > February 28th, so secure your free ArcSight Logger TODAY! > http://p.sf.net/sfu/arcsight-sfd2d > _______________________________________________ > Fedora-commons-users mailing list > Fedora-commons-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/fedora-commons-users ------------------------------------------------------------------------------ Special Offer-- Download ArcSight Logger for FREE (a $49 USD value)! Finally, a world-class log management solution at an even better price-free! Download using promo code Free_Logger_4_Dev2Dev. Offer expires February 28th, so secure your free ArcSight Logger TODAY! http://p.sf.net/sfu/arcsight-sfd2d _______________________________________________ Fedora-commons-users mailing list Fedora-commons-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/fedora-commons-users
