Uniform Resource Citation

Introduction

I'm really fuzzy in this whole area. Is there a connection between Z39.50 and these? Doesn't look like it from the more recent stuff I've seen, but it pops up now and then. If you know more about this, send me mail at dana@acm.org.

The URC specs are still being hashed out, and a number of people from the library community are involved. There is some effort to be able to map cleanly in and out of MARC format.

There seem to be multiple camps, each interested in using URC's for a different purpose, which I think is why I'm getting very confused. One group sees them used as an extension of the URL's we all know and love, while another sees them as being used to hold and communicate complicated information such as bibliographic data. They're both right, but usually they concentrate on one to the almost exclusion of the other. Until I better understand this, I'm just going to put lots of information here.

Description

From Jim Fullton's paper Network Information Dissemination Standards and Z39.50:

The Uniform Resource Citation

If a set of documents are available on the network for searching and retrieval through a communications interface such as Z39.50, some mechanism must exist for informing the user what has been found by a given search. While this sounds like a fundamentally simple problem, it is fraught with potential pitfalls. The data items that match the search query need to be summarized so the user may decide which is the most appropriate item for purchase or further review. This summary must be formatted in a consistent manner, based on a standard, so that client software can process the responses appropriately. This summary must also contain any necessary legal admonishments to the consumer regarding copyright, purchase costs, etc.

This summary unit standard is under consideration by the IETF as a Uniform Resource Citation, or URC. The URC is a standard collection of data in a predefined format that can be returned to a client as the result of a search or browse operation. The URC also contains location information for the data item, so the item may be quickly retrieved once the consumer has made a decision about the applicability of the item.

References

IETF URI archives
Network Information Dissemination Standards and Z39.50
Z39.50 resources by Robert Waldstein.
WWW Names and Addresses, URIs, URLs, URNs by Tim Berners-Lee.
Notebook on Citation, Linking, and Reference Strategies by Dan Connolly.
WWW gateways to Z39.50 OPACs at the University of Lund, Sweden.
Uniform Resource Identifiers from Michael Mealling
Encoding and Use of Uniform Resource Characteristics a working paper from Michael Mealling that gives a hypothetical example of a search through a whois++ database.

Tool Support

Michael Mealling has a link to a Whois++ and URN Software Archive that is supposed to contain a list of tools, but I cannot link to it.

The URC requirements and URC specifications are in the draft stages.

UR Terms

From Tim Berners-Lees's paper. See his paper for the full explanations and details.

URI: Universal Resource Identifier. The generic set of all names/addresses which are short strings which refer to objects.
URL: Uniform Resource Locators. Basically a pointer to an address rather than to a particular, persistant, object.
URN: Uniform Resource Name. Under development. Basically an object with strong persistance (more so that internet hosts or organizations).
URC: Uniform Resource Citation. Tim writes: " A set of attribute/value pairs describing an object. Some of the values may be URIs of various kinds. Others may include, for example, authorship, publisher, datatype, date, copyright status and shoe size. Not normally discussed as a short string, but a set of fields and values with some defined free formatting."

Current Minimal URC set

URN:
URL:
LIFN:
Author:
Title:
Subject:
Abstract:
Version:
Pub Date:
Publisher:
Notes:
Signature:

An example

This is from a working paper on the specification, and is probably obsolete already. But it might give you an idea of what's being talked about.

URN:IANA:626:oit:cs:ftp-and-telnet
Author: Arrowood, Adam 
{:
  URN:IANA:626:oit:ns:Adam.Arrowood
  URL:http://bastille.oit.gatech.edu/
  {:
    Content-Type: text/html
    Content-Size: 2008
  }:
}:
URL:http://www.gatech.edu/oit/cs/ftp-and-telnet.html

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18 December 1994

Dana Jacobsen
dana@acm.org