Technical Notes
The PADI website was developed in two phases. In phase 1 (released in
1999) PADI was migrated from manually-edited lists of resources to a subject
gateway service with a browse interface refreshed dynamically from a metadata
repository and a search interface enabling users to search the repository using
a range of search criteria, including fielded searching. In phase 2 (released
in 2001) a distributed update capability was developed that has enabled
maintenance of the repository to be shared with other agencies.
The metadata repository is based on Oracle, the search interface uses
Inktomi Enterprise Search (Ultraseek) and
the application has been developed using the WebMacro Java servlet framework.
Specifications for the PADI Subject Gateway Project were developed
taking into account the National Library of Australia's
Best Practice Checklist for
Australian Subject Gateways. An assessment of the extent to which PADI
meets best practice according to this checklist is given below:
Content Characteristics | Business
Characteristics | Functional Characteristics
Content Characteristics
- The gateway may describe both print and electronic
resources. It should be noted that gateways currently carry with them an
expectation of access to content in real time.
-
PADI describes quality digital preservation resources
regardless of format. Where there is no direct access to content, users have
the option of viewing the full repository record, where there may be more
information about the availability of the resource.
- The gateway may include professionally produced
descriptions of the resources. Such descriptions may pertain to the content of
the resource, in a form ranging from a short annotation to a review. Metadata
will be applied to facilitate the description of other attributes of the
resource, such as its title, author, format or location.
-
PADI resource descriptions are created by information
professionals from each of the participating agencies using metadata
appropriate to the description of each resource type.
- The resource types included may describe people, places,
events, works
-
PADI describes events and works. The same metadata schema is
used for both to simplify maintenance and processing issues. A separate schema
for describing events may be considered as an enhancement when standards in
this area have evolved.
- Works may be described at collection, whole item, part item
or analytical level.
-
PADI describes works at any of these levels if they fall
within scope. Four types of relationship are supported by the PADI
Metadata Schema: Is Review Of, Is Paper Of, Is Part
Of and Is Archived Version Of.
- Resources should be indexed according to a recognised
subject classification scheme in order to enable subject browsing. Controlled
vocabulary systems such as subject heading lists and thesauri should be used in
this process.
-
PADI resources are described using the
PADI Thesaurus.
- The resources described in the gateway may be uniquely
Australian, or of high use value within Australia.
-
PADI is being developed with appropriate partners as an
international subject gateway. PADI content will be of high use value within
Australia and overseas.
- The resources linked from the gateway must go through a
selection process conducted by the jurisdiction responsible for the gateway, to
ensure a high level of quality and relevance to the subject matter. There
should be a written policy listing selection criteria to facilitate this
process.
-
The National Library of Australia manages this process with
the help of an international advisory committee. A document outlining the
PADI Selection Criteria is publicly accessible
from the PADI web site.
- The resources must have their currency maintained. This may
be managed by sub-jurisdictional partners through human intervention, or by an
automated process, or by a combination of both strategies. There should be a
written policy detailing collection maintenance issues and procedures.
-
The National Library of Australia is committed to providing
the resources needed to maintain the currency of the PADI service. The PADI
Subject Gateway Project minimises the costs of meeting this criterion by
automating processses and enabling the workload to be shared with partners via
distributed data entry and review.Collection maintenance issues and procedures
are documented in PADIUpdate Help which is
accessible to all registered users of the distributed PADI update
function.
- The metadata describing the resources in the gateway must
meet a recognised standard for resource discovery ...
-
PADI uses the Dublin
Core metadata schema in all processes involving interoperability with other
systems.
- Extensions to the above-listed metadata may be created, but
must be managed through cooperative, responsible and secure processes, to
ensure Australian best practice in standards application.
-
The full PADI metadata schema is
described on this site.
- The copyright of resources linked from the gateway may be
managed by the sub-jurisdictional partners or by the host partner.
-
Copyright of resources is recorded where publically available.
PADI does not extend to the management of copyright, which is seen as the
responsibility of the publisher.
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Business Characteristics
- The gateway should be hosted in Australia, although it may
be mirrored internationally.
-
PADI is hosted by the National Library of Australia.
- The gateway host should have recognised jurisdictional
carriage of the subject area, either through a statutory or other clear
obligation.
-
The National Library of Australia is recognised nationally and
internationally as a centre of excellence in the area of digital
preservation.
- Contributions to the gateway must be made by a range of
partnered organisations and institutions, not a single business entity.
-
The technical infrastructure supports the development of
formal business arrangements with partners who wish to contribute to the
gateway.
- The gateway should be promoted through more than one
Australian entry point.
-
PADI is promoted through a range of entry points, both in
Australia and overseas.
- The gateway may provide links to other Australian, and
overseas, gateways.
-
PADI lists such gateways as resources.
- The gateway must ensure the long-term sustainability of its
service, which may be addressed by a strategic plan covering business and
marketing issues.
-
This is being addressed both in business and system
terms.
- The gateway should address the responsibility of long-term
access to content by taking on a management and preservation role for the
Australian resources within its purview, or by supporting national initiatives
which aim to do so...
-
This is being addressed through the
Safekeeping Project.
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Functional Characteristics
- The gateway must support both browse and search access
through the use of a metadata-enabled search engine and other value-added
features.
-
PADI has both browse and search interfaces generated
dynamically from a metadata repository. Important value-added features are the
ability to search the PADI Thesaurus and the ability to conduct a full-text
search of linked web sites. In the current version, only the linked page is
indexed. An element has been added to the PADI resource record to enable PADI
managers to record the level to which the site should be indexed for this
service.
- The selection criteria used to identify resources, and the
metadata schema used to describe them, should be made publicly accessible.
-
PADI is a subject gateway to digital preservation resources. A
document outlining the PADI Selection Criteria is
publicly accessible from the PADI web site. The PADI Metadata Schema is published on the PADI Web
Site.
- The Web access component of the gateway must support a link
to the actual content of a resource or its digital surrogate.
-
Where online content exists, PADI includes a link. The PADI
service would not be sustainable if content had to be created as part of the
indexing process for resources not directly accessible online. It is considered
more important that quality digital preservation resources are brought to
users' attention regardless of format, than that user's expectations for direct
access are met in all cases. For material not directly accessible online a full
resource description acts as the digital surrogate.
- The gateway may provide links to related free or paid
services, but without a mandatory requirement to provide e-commerce support for
them. It should be noted that gateways currently carry with them an expectation
of free access.
-
PADI is freely accessible and provides no e-commerce
support.
- Access to each type of resource may be exploited by
alternative entry points within the same gateway.
-
A variety of sorting and filtering mechanisms are applied to
the resources indexed for PADI depending on resource type.
- The gateway should meet accessibility criteria as outlined
by the W3C Web Accessibility Initiative, in their Web Content Accessibility
Guidelines. The content should be accessible to everyone, including users with
disabilities and users of text-only browsers.
-
The PADI web site meets Conformance Level A of the W3C
Web Content Accessibility
Guidelines.
- The gateway should make provision to support a standard form
of cross-gateway-searching, such as Z39.50 or HTTP.
-
Dublin Core metadata is embedded in all pages generated as
part of the Browse interface. Gateways harvesting this metadata will be
indexing PADI outputs consisting of lists of resources on a given topic or in a
given category. Individual PADI resource records are also available in the form
of metafiles containing embedded DC metadata in the head section and the
displayed record in the body. These metafiles are the mechanism currently used
to generate the indexes to support the search function. They are not publicly
accessible but could be provided to another gateway under a formal business
arrangement. The Inktomi Enterprise Search (Ultraseek) also supports the
Z39.50 search and retrieval
protocol.
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NATIONAL LIBRARY OF AUSTRALIA, Canberra, ACT 2600, AUSTRALIA
Telephone + 61 2 6262 1111; Facsimile +61 2 6257 1703; Telephone Typewriter
Number: 1800 026 372
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