Presentation on theme: "T. Baker / 23 Sep 2000 Dublin Core Qualifiers and A Grammar for Dublin Core Thomas Baker DC-8, National Library of Canada, Ottawa 4 October 2000."— Presentation transcript:
T. Baker / 23 Sep 2000 Dublin Core Qualifiers and A Grammar for Dublin Core Thomas Baker DC-8, National Library of Canada, Ottawa 4 October 2000
T. Baker / 23 Sep 2000 A pidgin for digital tourists Metadata is language DC: small language -- pidgin -- for searching across domains using a few familiar attributes "Pidginization": tourists learning simple phrases to order beer in an unfamiliar language We are all "tourists" on the global Internet. A pidgin for using the Web to find resources across multiple domains.
T. Baker / 23 Sep 2000 A grammar of Dublin Core http://www.gmd.de/People/Thomas.Baker/DC- Grammar.html By design not as subtle as mother tongues, but easy to learn and extremely useful in practice Pidgins: small vocabularies (Dublin Core: fifteen special nouns, lots of optional adjectives) Simple grammars: sentences (statements) follow a simple fixed pattern...
T. Baker / 23 Sep 2000 Resourcehasproperty DC:Creator DC:Title DC:Subject DC:Date... X implied subject implied verb one of 15 properties property value (an appropriate literal) [optional qualifier] qualifiers (adjectives)
T. Baker / 23 Sep 2000 Element Refinements Make the meaning of an element narrower or more specific. –a Date Created versus a Date Modified –an IsReplacedBy Relation versus a Replaces Relation A refined element shares the meaning of the unqualified element, but with a more restricted scope. A client that does not understand a specific element refinement term should be able to ignore the qualifier and fall back on the broader meaning of the element.
T. Baker / 23 Sep 2000 Value Encoding Schemes Pointers to standard encoding schemes that help interpret or parse an element value Says that the value is –a term selected from a controlled vocabulary (e.g., Library of Congress Subject Headings) –a string formatted in a standard way (e.g., "2000-01-01" as an ISO8601 expression of a date) If an encoding scheme is not understood by a client or agent, the value should still be "appropriate" and usable for discovery. Even if its scheme is unknown, a value should not be misleading.
T. Baker / 23 Sep 2000 Dumb-Down Principle for qualifiers The fifteen elements should be usable and understandable with or without the qualifiers Like saying that nouns can stand on their own without adjectives If your search engine encounters an unfamiliar qualifier, look it up somewhere -- or just ignore it! To test whether a qualifiers are "good", cover the qualifiers with your hand and ask: –Does the statement still make sense? –Is it correct?
T. Baker / 23 Sep 2000 Review and approval status DCMI Usage Committee reviews proposals for qualifiers Evaluates proposals in light of grammatical principles (are the qualifiers ignorable?) Tiered model of approval status (tentative): proposed, conforming, recommended, obsolete
T. Baker / 23 Sep 2000 History of a new process 1998, Nov: DC-7, element-specific working groups form to propose useful qualifiers 1999, Oct: DC-8, breakout groups review proposals against principles; the Usage Committee forms 2000, Jan: intended deadline passes 2000, Feb: formal principles reformulated in Usage Committee 2000, Jul: first qualifiers are published
T. Baker / 23 Sep 2000 A not-so-good example ResourcehasCreator "Last.name: Smith First.name: John Type: Person Affiliation: IBM"
T. Baker / 23 Sep 2000 Value Components: proposed as a third type of qualifier -- and rejected Property TypeTitleDateCreator Information resource HASA "J.Smith" VC HASA Type "Person" Affiliation "IBM"
T. Baker / 23 Sep 2000 Perhaps we should move them to... Element TypeTitleDateCreator Information resource HASA "J.Smith" VC HASA Type "Person" Affiliation "IBM"
T. Baker / 23 Sep 2000...a Core Element Set for Agents? Property Name Property Value TypeAffiliationBirthdateName Person (or Corporation) "J.Smith" "IBM""Person""1947-03-30" HASA
T. Baker / 23 Sep 2000 Richer metadata languages Complexification compromises the pidgin Richer vocabularies and grammatical structures needed for describing multiple related entities (resources, the people who created them, their life-cycle events...) Plenary II: Modular management of complexity –Application profiles –Structured metadata for richer description DCMI Architecture Working Group