DCMI Registry Functional requirements 2001-08-19
*****This is a draft document****** work in progress******
1. Background
This document is a more detailed elaboration of requirements for
the DCMI Registry. It follows on from the high level overview Purpose
and scope of DCMI Registry 2001-05-11. It is intended that these
detailed requirements will inform further development of the prototype
over the next few weeks.
The DCMI registry is designed to provide an added value 'registry
service' to assist humans and software obtain reliable trusted information
about DCMI terms. It is expected and encouraged that other registry services
will add value in other ways, for example by providing domain specific
approaches to DCMI terms. Readers should be aware that the DCMI Registry
exists alongside the straightforward 'registry service' provided by the
web i.e. it will be possible to link over the web direct to DCMI schemas
by means of resolvable DCMI namespace URI's (using HTTP GET namespace
URI).
2. The purpose and scope of the DCMI Registry
The purpose and scope is amended from Purpose
and scope of DCMI Registry 2001-05-11
-
To assist DCMI to manage the evolution of DC vocabularies
-
To provide authoritative definitions of recommended DC elements, qualifiers
and controlled vocabularies
-
To identify DCMI recommended names for schemes
-
To express these 'controlled metadata sets' and the relationships between
them in machine readable schema language and in human readable mode.
-
To provide a user friendly interface to the registered metadata ( e.g.
search and browse facility, browseable element set lists, links to annotations
and guidance on use of DC elements and qualifiers)
-
To manage multilingual aspects of DC.
3. Users
We have identified four categories of users of the registry
-
information seekers : those looking for up to date information on
the semantics of DCMI terms. these might typically be metadata creators,
information specialists implementing new systems and looking for appropriate
terms for their schemas, librarians, etc
-
computer specialists : developers using RDF/XML, software engineers
etc
-
applications : software using the regsitry to navigate information
about DCMI terms
-
administrators : who may add, edit and delete entries
The priority is to define a minimum functionality to give the first catefory,
information seekers, a user friendly impression of the registry so thay
can evaluate it. Because a lot of information seekers will not have English
as their native language, we need to prioritise multilingual functionality
in the first phase. Also it will help to ensure correct design decisions
by implementing multilinguality in the first phase. Albeit we accept there
may only be a limited implementation of multilinguality to begin with,
as it requires a lot of additional data to be entered. Also we want
to benefit from additional work on multilingual regiustries going on in
parallel in a different forum ( ULIS in Tokyo).
3. Phase 1 requirements
-
Content of registry
The registry will contain information about
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DCMI elements
-
DCMI qualifiers
-
DCMI controlled vocabularies
Initially we will include for all DCMI elements and qualifiers:
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Name - The label assigned to the data element
-
Identifier - The unique identifier assigned
to the data element
-
Registration Authority - The entity authorised
to register the data element (i.e. DCMI)
-
Language - The language of the term name,
definition and comment
-
Definition - A statement that clearly represents
the concept and essential nature of the term
-
Obligation - Indicates if the term is required
to always or sometimes be present (i.e. contain a value)
-
Datatype - Indicates the type of data that
can be represented in the value of the term
-
Maximum Occurrence - Indicates any limit
to the repeatability of the term
-
Comment - A remark concerning the application
of the term
-
Relation -
-
All this information is given explicitly or implied for all elements andqualifiers
in existing web documents [1] and [2]. Please note that within [2]
'Name' has been used incorrectly, it should be replaced by 'Identifier'
and 'Label' should be replaced by 'Name'. This usage accords with ISO 11179
[3]. Information for terms within controlled vocabularies is given in the
documents referenced at [4].
In addition users must be able within displays to distinguish whether
terms are elements or qualifiers or from controlled vocabularies; and
if the term is a qualifier whether it is an element refinement or an
encoding scheme. Users must be able to browse and search for these
categories of terms separately.
In addition users must be able to identify relationships between
terms e.g. to see that Alternative is a sub-property of Title.
For controlled vocabularies......
3.1 Requirements for information seeker interface
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browse through lists of terms
Users will want to browse separate summary lists of the following
-
names of the categories of DCMI terms that have been registered
(i.e. elements, element refinement qualifiers, encoding scheme qualifiers,
controlled vocabularies). Note this may not be the same thing as 'all schemas
available in the registry' as the registry will include schemas used for
'managing' the data. users will want to link from the list of categories
to terms within those categories e.g. from 'DCMI elements' to a list of
summarised displays of infromation about those elements
-
all DCMI elements in summarised display
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all DCMI qualifier which are element refinements
-
all encoding schemes for which DCMI have recommended names
-
all controlled vocabularies [4]
Summary displays of terms might include name, identifier, relationship
to other terms. From summary displays users can link to full displays.
From the initial list users will want to link to all detailed information
available about a particular term.
Listing should be keyed by term name (e.g. contributor, subject,
title etc) in alphabetical order
Users will want to select their preferred language for translation
of name and definition etc in the list
-
Search contents of registry
User should have some choice in what fields (properties and classes) are
searched. For example users will not be interested in searching eor schema
properties themselves which exist for the description of terms (i.e. the
search should be limited to metadata about DCMI terms. and should exclude
schema that exist for managing the registry.
Users must be able to
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enter a string to match name of DCMI terms (e.g. title, alternative title
etc)
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enter a string which will be used as free text search of values describing
DCMI terms and schemas (e.g. any mention of creator, subject, Dewey)
On the top screen one needs to offer this browse facility. need to
replace 'properties/classes' with 'names of terms/schema types' or
some such
Indicate on the top screen search box which properties within
a schema are being searched
e.g. Search all values associated with DCMI terms (rdf:ID? rdfs:label?
eor:comment? rdfs:comment?) to find the string "title"
Search on rdfs:subPropertyOf contains "title" (to get me properties
which qualify title etc)
In all searches user must be able to specify which language of name/definition/comment
they wish to search.
-
display of retrieved data, input screens etc
All RDF jargon needs to be replaced with more accessible terminology. The
terminology decided on will need to be available in user's language of
preference.
Within displays all 'property' and 'class' labelling must be replaced
with easily understood terminology.
Displays should be of human readable information with RDF syntax stripped
away.
For example:
Suggested display of information about a schema (just bold text
displayed)
Schema
DCMI elements (LINK to summarised list of elements)
( rdf:type
http://dublincore.org/2000/03/13/eor#Schema)
(dc:title) Title
The Dublin Core Element Set v1.1
dc:description Description
The Dublin Core metadata vocabulary is a simple vocabulary intended
to facilitate discovery of resources.
dc:publisherRegistration Authority
The Dublin Core Metadata Initiative
dc:date
2000-07-02
dc:language Language
English
dc:relation Relation
Qualified by...
Full display of information about a term
-
Name - The label assigned to the term
-
Identifier - The unique identifier assigned
to the term
-
Registration Authority - The entity authorised
to register the data element (i.e. DCMI)
-
Definition - A statement that clearly represents
the concept and essential nature of the data element
-
Obligation - Indicates if the data element is
required to always or sometimes be present (contain a value)
-
Datatype - Indicates the type of data that can
be represented in the value of the data element
-
Maximum Occurrence - Indicates any limit to the
repeatability of the data element
-
Comment - A remark concerning the application
of the data element
-
Relation - Indicate whether element has qualifiers
(sub-properties) or to which element(s) a qualifier relates
(LINK to
appropriate terms)
-
Category - whether term is element, element refinement,
encoding scheme, term from controlled vocabulary
Summary display of information about a term:
-
Name - The label assigned to the term (LINK
to detailed information)
-
Identifier - The unique identifier assigned to
the term
-
Registration Authority - The entity authorised
to register the data element (i.e. DCMI)
-
Relation - Indicate whether element has qualifiers
(sub-properties) or to which element(s) a qualifier relates
-
Category - whether term is element, element refinement,
encoding scheme, term from controlled vocabulary
Phase 2 requirements:
The following requirement was originally recommended for implementation
-
To enable DC elements and qualifiers to be annotated with a status such
as 'proposed', 'recommended', 'deprecated' (these 'status' terms to be
provided by the usage committee)
-
To enable implementors to submit proposed extensions and application
profiles
However my understanding is that the Usage Committee has decided it does
not want to refer to 'proposed' terms within the registry. Also that the
Usage Committee sees no immediate requirement for 'deprecated' status.
This means this requirement can be slipped to a later phase.
Other requirements to be phased in, priority as indicated:
High priority:
-
To provide access to DCMI domain specific 'application profiles' e.g. the
DCMI Education group application profile
Priority to be established:
-
To register authoritative mappings and crosswalks between DC and other
metadata sets (e.g. ONIX, MARC etc.)
-
To provide information on deployment (e.g. which services are using particular
domain specific extensions)
-
To provide links to best practice, guidelines for use (perhaps link into
the user guide?)
Constraints/Assumptions
-
We will use RDF schema language in the first instance as this is supported
in the prototype software.
-
We have been advised by the usage committee that there will be no requirement
for versioning DCMI terms
-
The Working Group on Dublin Core in Multiple Languages takes the position
that the reference language of the international Dublin Core community
is English inasmuch all of its outputs are discussed and approved in English
[5]. Accordingly, the English version of the Dublin Core has a special
status as the canonical result of an international process.
Dependencies
In order to express DC elements and qualifiers in RDF there needs to be
a decision on the namespace model for DCMI, in particular we would like
to use the correct URIs within linked schemas. we are working with draft
schemas at present.
Development work on the DCMI Registry software is currently undertaken
at OCLC. Work on multilingual aspects is also being taken forward at ULIS,
Tokyo.
Definitions of terms in this document
Name: Single or multi word designation assigned to a term. Serves
as human readable label, can change within an implementation or in multilingual
context.
Identifier: A language independent unique identifier of a term,
a machine readable 'tag', cannot change.
DCMI term : A DCMI term is a metadata element or qualifier defined
in a DCMI recommendation. Each
DCMI term is identified by a Uniform Resource Identifier (URI) within
a DCMI namespace.
DCMI namespace
A DCMI namespace is a collection of DCMI terms.
Each DCMI namespace is identified by a URI.
DCMI recommendation
A DCMI recommendation is a human-readable
document that defines one or more DCMI terms.
Application profile : a type of schema describing a set of terms
(selected from already existing schema) as optimal for use within a particular
implementaion or domain.
References
[1] Dublin Core Metadata Element Set, Version 1.1: Reference Description
http://www.dublincore.org/documents/dces/
[2] Dublin Core Qualifiers
http://www.dublincore.org/documents/dcmes-qualifiers/
[3] ISO/IEC 11179-1 Specification and standardization of data elements.
Parts
1-6
http://www.sdct.itl.nist.gov/~ftp/x3l8/other/coalition/Ovr11179.html
[4] Controlled vocabularies:
DCMI Box Encoding Scheme: Specification of the spatial limits of a
place, and methods for encoding this in a text string.
http://dublincore.org/documents/2000/07/28/dcmi-box/
DCMI Period Encoding Scheme: specification of the limits of a time interval,
and methods for encoding this in a text string.
http://dublincore.org/documents/2000/07/28/dcmi-period/
Draft RDF schemas
DCMI Point Encoding Scheme: a point location in space, and methods for
encoding this in a text string
http://dublincore.org/documents/2000/07/28/dcmi-point/
DCMI Type vocabulary
http://dublincore.org/documents/2000/07/11/dcmi-type-vocabulary/
[5] Plans for a distributed registry of Dublin Core in multiple languages.
Thomas Baker. 1998-10-28
http://www.dublincore.org/documents/1998/10/28/distributed-registry/
[x] Draft schemas
e.g. http://homes.ukoln.ac.uk/~lisap/dcmi-ns/dcmes-rdfs.xml
http://dublincore.org/2000/03/13/