Re: [urn] [apps-discuss] URNs are not URIs (another look at RFC 3986)
jehakala@mappi.helsinki.fi Fri, 02 May 2014 15:06 UTC
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Date: Fri, 02 May 2014 18:06:42 +0300
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From: jehakala@mappi.helsinki.fi
To: John C Klensin <john-ietf@jck.com>
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Cc: julian.reschke@gmx.de, urn@ietf.org, Graham Klyne <GK@ninebynine.org>, apps-discuss@ietf.org
Subject: Re: [urn] [apps-discuss] URNs are not URIs (another look at RFC 3986)
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Hello, Quoting John C Klensin <john-ietf@jck.com>: > Hi. > <snip> ... one very quick observation in response to part of > Larry's note... > > --On Tuesday, 15 April, 2014 16:25 +0000 Larry Masinter > <masinter@adobe.com> wrote: > >> The only thing that makes something a name 'persistsent' is >> the existence of a name resolution service or method which >> persists. The syntax or namespace is irrelevant. 'persistent' >> isn't binary, it's just "how long". Everything has a life-time. >> >> http://masinter.blogspot.com/2010/03/ozymandias-uri.html > > I think the above largely misses the point and that, in a sense, > your blog posting illustrates the point although not in the way > you probably intend. "Persistent identifier" entered the IETF > vocabulary a long time ago but may not be very look terminology. > > Some objects -- like stone statues if one doesn't care whether > they remain intact and standing-- have very long life > expectancies. Others, like people, have shorter ones. The library point of view to this is that Shelley's Ozymandias has an extremely long life expectancy as a work. It will exist at least as long as there is at least one copy left of it, in some physical (printed or digital) form. In principle the work itself may survive even longer, if 1-n people have memorized it before the last copy vanishes (which will inevitably happen). Persistence of works, their manifestations and identifiers assigned to them is primarily an organizational issue. For instance, publications will survive a long time because national libraries look after them. Some of us are also busy harvesting web pages, using the same technologies as the Internet Archive. Likewise archives and museums will keep some materials for hundreds of years. This is the community which needs persistent identifiers and is already actively using them (and understands pretty well how to do it). Now, in order to identify Ozymandias, the following steps are needed: 1. Give an identifier to the (immaterial) work, and provide metadata about the poem. 2. Give identifier to a manifestation of the work. The identifier system used can be an ISBN, if Ozymandias is published in a collection of Shelley's poems. Once the identifier has been assigned, provide metadata about the book. If the resource is not a book, use other identifier system such as NBN. 3. If the resource is digital, provide a link (using the existing identifier) from the metadata record to the resource. Traditional identifiers can be made actionable in the Internet as URNs, but other PID systems such as DOI, Handle, ARK et cetera can also be used. As an aside, new features which URNbis has built are not in conflict with other PIDs; on the contrary, they can use them as well. The only slightly problematic case is ARK since it has its own established practice for using query. The essential difference between this PID-driven approach and that of some people on this list is that for me, URLs like this http://www.poemhunter.com/poem/ozymandias/ or even this http://ozymandias.perm are not identifiers, first and foremost because their assignment process is not managed. One may argue that sometimes there are no proper identifier system to use but this is not true; Handles, DOIs and URNs can be applied to anything out there). Second, there is a problem that URLs are not persistent, since they are technology dependent. Even if they had the same organizational support than the URN-based link supported by the national library (which is very unlikely) it may become very difficult to support these URLs long before reading the resources requires digital archaeology. Some people on this list have argued that http://urn.fi/URN:ISBN:978-952-10-9658-7 or other PID with embedded resolver address is no different from e.g. http://ozymandias.perm. But in this case the syntactical similarity is deceptive; URN and other PIDs must be resolved before the current URL (URLs) of the resource is found, so all kinds of interesting stuff can be done in the resolution process before the result is passed to HTTP. And once Resolver Discovery Service is in place, it will be possible to drop the resolver URL from the URN string, and make the difference between URLs and URNs more clear. But URIs > (with or within including URNs) aren't objects, they are object > reference that, like most good references, involve some degree > of abstraction. Now, "Ozymandias" is a very long-persistent > reference. It isn't the object. It is a somewhat ambiguous > reference because it can refer to the statue, the poem, your > blog posting, and probably several other things, but has a long > duration, perhaps one that is long enough to survive the objects > it references (just like titles of long-lost books). But, as a > reference, it is that persistent because it is not bound to a > retrieval mechanism that has its own persistence properties. References to immaterial objects (works and expressions, the latter meaning for instance translations of works) are persistent, but they do require metadata since otherwise they may be ambiguous. For instance, we are talking about Shelley's poem, first published in The Examiner, 11 January 1818, along with Hymn to intellectual beauty. There is also book by Thomas Monteleone which has the same name. > > Whatever its other properties, > http://masinter.blogspot.com/2010/03/ozymandias-uri.html > is lousy as a persistent identifier. URLs really should not be called identifiers. There is a fundamental difference between assigning a persistent identifier using a managed process (which includes creation of descriptive metadata about the resource) and getting a URL to a web page. One problem I and others have with the concept of URI is that it blurs what should be a clear difference between locations and proper identifiers. Anyone should be allowed to give the former, but identifier assignment for resources that are to be kept for centuries is not something anyone is allowed do. Of course even people assigning proper identifiers such as ISBNs and ISSNs make mistakes, and there are pressures to use these systems in less than optimal manner, but that is not the key issue here. What is important is that any digital resource that will be preserved for future generations will require a persistent identifier. Millions and millions of them - Handles, DOIs, URNs, ARKs) have been assigned already by libraries, publishers, universities, archives and museums. In order to optimize the tools used for generating and resolving URNs and other PIDs, we need some new functionalities such as the possibility of using fragments and queries. It depends on the > availability of "http" (or something called that) as a retrieval > mechanism. It depends on there being a DNS, on there being a > TLD named "com" an SLD named "blogspot", and both of them having > certain properties of which HTTP can take advantage. It seems that the extent to which URLs are dependent on underlying technologies and the impact this will have on URLs in the long run (after, say, a few decades) is not properly understood yet even by those communities which must preserve things for extended periods. It might be useful to explain where the problems are, and make a guesstimate of when each of these issues might emerge. > "Ozymandias", and even the potential URN > urn:poems:Shelley/Ozymandias are more persistent because they > represent a higher level of abstraction and are not tied to > either a location or a retrieval/access method. Use of a > hypothetical ISPN (International Standard Poem Identifier) in > the form urn:ispn:NNNN-NNNNNN-NNNNNNNNNNNNNNNNNNNN might or > might not be more persistent: it would be an exact identifier of > something and makes equivalence comparison more feasible and > less ambiguous, but it is probably tied to a database to > actually identify an object and such databases may be more or > less available and persistent than access methods and/or the DNS > (which is, after all, just another database). In practice there will be ISTC (International Standard Text Code) assigned to the poem. ISTC can be expressed as URN (urn:istc:xxxx-xxxx-xxxx-xxxx). Library databases all over the world will have work metadata about the poem (once one library has catalogued it, it can be copied to the OPAC of every other library in the world). From the work record there will be persistent links to manifestation records, which in turn will contain the locations of the manifestations - physical shelf locations for printed stuff, and links using persistent identifiers to electronic resources. When thousands of library OPACs have the same metadata record, it is important to have just persistent identifier -based links in them; resolving these URNs / Handles / etc. to URLs must be centralized. Then it is not necessary to modify every OPAC when URLs change. Naming / identification has at times been discussed on this list in a very abstract level. For most resources that will be preserved for long term, things are not that complex. There are guidebooks for using ISTCs, ISBNs, ISSNs, NBNs and so on. In those namespaces at least it is not necessary to be familiar with Heidegger in order to be able to assign identifiers for things. On the other hand, it is these existing practices which are in conflict with some of the principles expressed in RFC 3986. If fragment were to identify something (instead of just pinpointing a location within the identified resource) the new URN syntax would not be OK of most identifiers used in libraries and publishing sector. The same applies for query. Juha > > Regardless of what one calls them, I suggest that > access-method-dependent identifiers (http:..., > NineTrackTape:??42.3744°?N,?71.1169°?W?123456 (where "?" > represents one or more carefully-chosen delimiters that may not > have RFC 3986 semantics), ...) are different kinds of creatures > than either the objects to which they refer or names of those > objects that are not, in the sense of the above, method or > location-model dependent. > > More soon. > > john > > > _______________________________________________ > urn mailing list > urn@ietf.org > https://www.ietf.org/mailman/listinfo/urn
- [urn] URNs are not URIs (another look at RFC 3986) John C Klensin
- Re: [urn] URNs are not URIs (another look at RFC … Julian Reschke
- Re: [urn] URNs are not URIs (another look at RFC … John C Klensin
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Martin J. Dürst
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Graham Klyne
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Graham Klyne
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Larry Masinter
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… John C Klensin
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Phillip Hallam-Baker
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… John C Klensin
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Phillip Hallam-Baker
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Julian Reschke
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Nico Williams
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Julian Reschke
- Re: [urn] URNs are not URIs (another look at RFC … Dale R. Worley
- Re: [urn] URNs are not URIs (another look at RFC … Dale R. Worley
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Phillip Hallam-Baker
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Nico Williams
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Phillip Hallam-Baker
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Mark Nottingham
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Graham Klyne
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Scott Brim
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Mark Baker
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… John C Klensin
- Re: [urn] URNs are not URIs (another look at RFC … John C Klensin
- Re: [urn] URNs are not URIs (another look at RFC … Barry Leiba
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Phillip Hallam-Baker
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… John C Klensin
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Scott Brim
- Re: [urn] URNs are not URIs (another look at RFC … John C Klensin
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Nico Williams
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Nico Williams
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… John C Klensin
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Barry Leiba
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Mark Baker
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Martin J. Dürst
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Martin J. Dürst
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Larry Masinter
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Tony Finch
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Phillip Hallam-Baker
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Maurizio Lunghi
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Phillip Hallam-Baker
- [urn] R: [apps-discuss] URNs are not URIs (anothe… Maurizio Lunghi
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Larry Masinter
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Edward Summers
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… John C Klensin
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Dale R. Worley
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Dale R. Worley
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Phillip Hallam-Baker
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… John C Klensin
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… jehakala
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… John C Klensin
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Juha Hakala
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Svensson, Lars
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… SM
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… jehakala
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… John C Klensin
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… SM
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Dale R. Worley
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Henry S. Thompson
- Re: [urn] [apps-discuss] URNs are not URIs (anoth… Henry S. Thompson