2011/1/27 Jonathan Rochkind <[log in to unmask]>: > "If the best you can do is an external Handle/PURL set-up, then it is better than nothing." > > I would say that it's SOMETIMES better than nothing. It depends on what you're doing, what your requirements and goals are. Not every application needs long-term persistence of URLs -- whether through an 'abstraction layer' or not. ('abstraction layer' is just an implementation detail to get long-term persistence of URLs accross systems changes, right? You don't always need something called an 'abstraction layer' to do that). Almost every application does need bookmarkable URLs for the short/medium-term though. If you're sacrificing short-term bookmarkable URLs for long-term-goal persistent but confusing/non-transparent/not-discoverable URLs, that may or may not be a good trade off. I *think* this may be pertinent, but it may also be a tangent. For the DLG[1] and CRDL[2], we make use of what for lack of a better term I refer to as the DLG handle service. It's internal to our shop, but external to the collections it serves, and is my attempt to be able to provide bookmarks to items that may have been retrieved via non-bookmarkable urls. Both DLG and CRDL are aggregators of both local and state-wide/nation-wide collections. So the handle service maintains a concept of "repository" (the owner of the collection), "collection", and "item". Each of these has an ID, e.g., the ID for the repo "Digital Library of Georgia" is 'dlg', for the coll "Vanishing Georgia" is 'vang', for the item "Photograph of Lillian Carter, Plains, Sumter County, Georgia, 1976" is 'sum150'. The item's bookmark then (with some handwaving about the repo id) is: http://dlg.galileo.usg.edu/vang/id:sum150 Other examples: A "persistent url" for a query in DLG: http://dlg.galileo.usg.edu/query:bush Item records *in the aggregator database* of DLG: http://dlg.galileo.usg.edu/id:dlg_bald_am-451 http://dlg.galileo.usg.edu/id:dlg_vang_sum150 Item records in the collections' sites: http://dlg.galileo.usg.edu/bald/id:am-451 http://dlg.galileo.usg.edu/vang/id:sum150 And similar examples from CRDL: http://crdl.usg.edu/query:bush http://crdl.usg.edu/id:lbj_timeline http://crdl.usg.edu/id:dlg_bald_am-1259 http://crdl.usg.edu/id:wsu_wsuboh_jacktanner To get to the point, when we display an item (in the interfaces that we control ourselves) we include in the item display a "Bookmark" url that is one of these handles. For example, the actual url for the last item above looks something like this: http://crdl.usg.edu/cgi/crdl?action=retrieve;rset=001;recno=4 That's clearly not bookmarkable outside of the existing browser session, so in the item display, we have this line: Bookmark: http://crdl.usg.edu/id:wsu_wsuboh_jacktanner In that line, the URL *is* clickable. I realize that this handle strategy flies in the face of "opacity", since the handle contains indicators of ownership. I guess I'm just not in that camp, at least not for these collections. Again, I'm not sure the above is really a useful response to the original query, but it came to mind, so I thought I'd toss it in. Regards, Brad [1] http://dlg.galileo.usg.edu/ [2] http://crdl.usg.edu/