[OAI-implementers] on the OAI-PMH data model

Michael Nelson mln at cs.odu.edu
Fri Mar 18 12:41:25 EST 2005

On Fri, 18 Mar 2005, Fabio Simeoni wrote:
> I wonder now if DP could be as good-willed as you are and yet avoid the
> bookkeeping you are doing by:
> (i) avoid updating the item/master-record datestamp when a format mapping
> changes, and
> (ii) use out-of-band techniques to tell harvester which are interested in
> the mapping change that, as a result of that change, they should do a
> historical re-harvest.

I don't understand why oob techniques would be required.  If a repo
exposes metadata formats:

	- xyz (native)
	- abc (dynamically generated from xyz)

it is easy for the repo to associate a datestamp with the mapping itself
("from" shown):

foreach $record (@records) {
  if ($request->format eq "abc") {
    if ( ($request->datestamp < $record->datestamp) ||
         ($request->datestamp < $map_to_abc->datestamp) ) {
           push(@result, $record);
  if ($request->format eq "xyz") {
    if ($request->datestamp < $record->datestamp) {
      push(@result, $record);

a new mapping of xyz->abc will not impact xyz harvesters, and keeping the
datestamp with the mapping function doesn't represent a hardship for the



> All the other harvester would still be spared from doing costly and yet
> irrelevant historical harvests. Of course, this requires DPs to know who's
> harvesting them and for what.
> Any comments appreciated.
> regards,
> fabio

Michael L. Nelson mln at cs.odu.edu http://www.cs.odu.edu/~mln/
Dept of Computer Science, Old Dominion University, Norfolk VA 23529
+1 757 683 6393 +1 757 683 4900 (f)

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