[urn] query component in URNs
Peter Saint-Andre <stpeter@stpeter.im> Thu, 21 February 2013 04:49 UTC
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Date: Wed, 20 Feb 2013 21:49:14 -0700
From: Peter Saint-Andre <stpeter@stpeter.im>
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Subject: [urn] query component in URNs
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 In the interest of moving forward with rfc2141bis and with my document editor hat on, I've been reviewing list discussions and earlier document versions so that we can be clear about open issues. Because the fragment identifier issue is quite large and has received a lot of discussion, I've decided to focus first on the issue of query components in URNs. Juha Hakala mentioned the topic in late 2010: https://www.ietf.org/mail-archive/web/urn/current/msg01485.html "From the PersID point of view, both <query> and <fragment> are vitally important. We support the idea of reserving <query> for the transfer of service parameters as a part of the resolution process." In March 2011, Juha again mentioned query components: https://www.ietf.org/mail-archive/web/urn/current/msg01507.html "As regards the URN syntax, the key issue - at least from my point of view - that should be discussed more widely is the usage of <fragment> and <query> in the way suggested in RFC2141bis. The reason why it is vital to make firm decisions concerning these features is that there are projects that intend to use both of them, and must have explicit permission and guidelines for doing that." Martin Duerst pointed out that nothing is really stopping us from allowing query components: https://www.ietf.org/mail-archive/web/urn/current/msg01510.html "That's quite different from the query part; if the urn spec wants to allow a "?" and some following stuff, it can do so, and it can put on the syntactic restrictions (as long as they are within the bounds of the URI spec) and semantic restrictions the WG deems appropriate." Although I don't claim to fully understand the proposed use of query components in URNs, it appears to be something that could be supported in, say, an HTTP-based resolution service. Thus a URN of urn:isbn:978-951-1-25645-8 could be resolved over HTTP: http://resolver.example.com/urn:isbn:978-951-1-25645-8?param=value However, that would not necessitate adding query components to URNs themselves. This appears to be consistent with something that Juha sent in August of 2011: https://www.ietf.org/mail-archive/web/urn/current/msg01574.html "The reason why URN:ISBN namespace does not allow fragments has to do with ISBN syntax. This is OK: http://urn.fi/URN:ISBN:978-952-10-7060-0 but I am not allowed to add anything to the namespace specific string even if the media type in which this book is published would allow that. Of course, adding <query> would be OK since it would not be part of the identifier. " And: https://www.ietf.org/mail-archive/web/urn/current/msg01582.html "According to the RFC2141bis, fragment ID - if we allow its use in the URN syntax - will be part of the identifier. An identifier which consists of and ISBN and a fragment no longer identifies the book as a whole but a component part of it. Whereas ISBN with <query> still identifies the book as a whole; the role of the <query> is to specify the resolution service the user wants." The issue arose again in December of 2011: https://www.ietf.org/mail-archive/web/urn/current/msg01665.html "No, I was just emphasizing the point that if we piggyback service parameters in <query> they will not be part of the URN itself. Whenever there are fundamental changes in technology, the URN itself remains the same, but the service parameters may be encoded differently." Confusingly (at least to me), in March of 2012 Juha made the following statement: https://www.ietf.org/mail-archive/web/urn/current/msg01735.html "As an aside, rfc3187bis is still out of date in the sense that it assumes (erroneously) that the <fragment> is part of the NSS. If this were so, you could not use <fragment> in the ISBN namespace since the ISBN standard does not allow the users to add anything to the ISBN string. But a construct where ISBN forms the NSS and <fragment> and <query> may be added to it, gives us free hands. I shall revise the I-D in this respect in the near future. Such revision requires also discussions with the International ISBN Agency, since via <fragment> usage URN:ISBN gains functionality which is not available in the ISBN itself. " Notwithstanding that statement, Section 2.3 of draft-ietf-urnbis-rfc2141bis-urn-03 contained the following text: The <query> part MUST NOT be present in any *assigned* URN. A <query> part can only be added to an assigned URN and appear in a URI *reference* [RFC3986] to a URN that is intended to be used with URN resolution services, and, in the spirit of the general specification of this part in RFC 3986, its purpose is restricted to indicate the requested URN resolution service and particular service aspects of the intended resolution response, e.g., the kind of metadata or content sought that are bound to a given object identified by the basic, assigned URN. I draw two conclusions: 1. A query component would not be needed to provide a persistent, location-independent identifer for, say, an ISBN resource like 978-951-1-25645-8. 2. Aside from a possibly ambiguous statement from Juha, no one has proposed that we modify the URN syntax to allow query components in URNs. Unless someone objects, I shall consider this issue closed. Peter - -- Peter Saint-Andre https://stpeter.im/ -----BEGIN PGP SIGNATURE----- Version: GnuPG/MacGPG2 v2.0.18 (Darwin) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQIcBAEBAgAGBQJRJadKAAoJEOoGpJErxa2pbC0P/A5QqNb365I5oz+gskNLr0dV 5vq4zBawxgRDUG8jf67l4ZuMeF6aMXOpSlHoJN3VbXt6nfwPgW4w221MSVJM0Dna 4rT9xviSZEjEPxpjkIPrwskSesfTkBcC/C1uH1pGnyLOcC1c0xerBUCyo3vcQUAB de4+iC1JNhQjF7jGCC4WP2jPfpk9AvP70mZrcvd1bNmMJmdgczONIAT5PaAj0xQO WK5glcKwCNvB34IrGU/WJuJpaJJ8yYBSd5OFH76D/cI27yf/I+v5sZANQDfXFMpI rb1yZMDWk1xvuawUgshP0dyCVdGDcSmIQnNOLURbHMDqXqidC5rstid87vdpq+O+ zlW3ubvLYJjhIBhTLqiD6LpuImzxzJMtx0/r5Tb1f2D2iuDIZ0boO/7+gfXH7pZ3 pj2CjWc+DPNOz075kDUxoCJ4QUyMA6kNenvcCh5bkW1FIypu95sMic8NeqWJs/KE wyLbQxYjkNwO0EyiC2M6ItmqmxHFrWXaAVGzyMrLeNAQIyqpi7moBZJtfTrPQAGe 7K08txf/W232IIqJ6M67g2vuLgmAg4X7oIj5JxQAmnluOOvDYJyRa2tpl+zxWxIh Tdx2ImQFZkAsgseL0dcAUtvOmTryIHdQ2mnHGdelDoRgxe/5FyoJ8e+4IjFfThKF r5NtgfCu+AqRQyuO2O8z =43Sg -----END PGP SIGNATURE-----
- [urn] query component in URNs Peter Saint-Andre
- Re: [urn] query component in URNs Keith Moore
- Re: [urn] query component in URNs Juha Hakala
- Re: [urn] query component in URNs Keith Moore