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DNER Architecture
Andy Powell
UKOLN, University of Bath
[email protected]
www.ukoln.ac.uk
Web of Science Enhancements Committee, Centre Point
5 March 2001
UKOLN is funded by Resource: The Council for Museums, Archives and Libraries, the Joint
Information Systems Committee (JISC) of the Higher and Further Education Funding Councils,
as well as by project funding from the JISC and the European Union. UKOLN also receives
support from the University of Bath where it is based.
Contents
• scope
• functional model
• network systems architecture
• discover
• request, access
2
Scope
What is the DNER?
DNER scope by content?
External
Institutional
Secondary Content
4
RDN
WoS
A&I
COPAC
Northern
Light
Primary Content
Map data
Full-text
images
statistics
Funded
but...
• … not a user view
• … not an institutional view
• user view based on personalised
landscape...
• own information foremost
• institutional (intranet or VLE)
• DNER and external (general Web stuff)
• probably with discipline or subject focus
• … difficult to scope DNER by content?
5
Information environment
• DNER is an information environment (a set of
services) that enables people to access and use
a wide variety of resources
• ‘resources’ are…
•
•
•
•
•
•
services / content
local / remote
primary / secondary, data / metadata
digital / physical
JISC funded / not JISC funded
policy controlled / non-policy controlled
• ‘access and use’ includes
6
• discover / locate / access
• use / reuse / create
• receive / provide / collaborate
Functional Model
What does the DNER do?
Currently...
Content
(local and
remote)
Web
Web
Web
Web
End-user
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Web
• end-user has to
interact with several
different services,
each with their own
user-interface
• what functional
model is supported?
• what can end-user
do?
Functional model
9
• move from user-need to
resource on desktop (physical or
digital)
• three stage ‘discovery process’
• ‘landscape’ and ‘survey’ collection level
• ‘discover’ and ‘detail’ - item level
• iterative process
• final ‘detail’ phase provides
information about how to request
instance of resource
• ‘detail’ may involve resolving
identifier or metadata for
resource using ‘resolver’
authenticate
landscape
survey
discover
useRecord
detail
request
authorise
access
useResource
DNER information flow
• process is iterative at all stages
• DNER not just a ‘provider to user’ flow
• users are both recipients of and creators
of both primary content, secondary
content and metadata
• DNER architecture needs to support
• collaboration and
• creation
• …as well as discovery, etc.
• current work on architecture doesn’t really
address this.
10
Network Systems
Architecture
How does the DNER do it?
Currently...
Content
Web
Current services
offer mix of
survey, discover,
detail, request,
access,
useRecord
functionality
12
Web
Web
Web
End-user
Web
End-user needs
to join services
together
manually - as
well as learning
multiple user
interfaces
Joining things together
• build framework for shared services
• DNER as coherent whole rather than lots
of stand-alone services
• two areas in particular...
• discovery
• finding stuff from multiple content providers
• locate/request/deliver
• streamlining access
13
Discover
• in order to allow end-user to discover
seamlessly across several network
services...
• services need to expose content for
machine use (m2m)
• expose metadata for
• searching
• harvesting
• alerting
• develop services that bring stuff together
• portals
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Portals
• portals provide access to multiple network
services
• there will be many kinds of portals...
• subject portals
• data centre portals
• institutional portals
• personal portals (agents)
• virtual learning environments
• thin portals (shallow linking)
• thick portals (deep linking, richer discovery
and use functionality)
15
Thin portal
Content
Web
Web
Web
Web
Authentication
Authorisation
Collect’n Desc
Portal
HTTP
End-user
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Searching
Content
Web
Web
Web
Web
Authentication
Authorisation
Broker
Z39.50
Bath Profile
Collect’n Desc
Service Desc
Portal
HTTP
End-user
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Sharing
Content
Web
Web
Web
Open
Archives
Initiative
Web
Authentication
Authorisation
Aggregator
Collect’n Desc
Service Desc
Portal
HTTP
End-user
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Open Archives Initiative
• OAI Metadata Harvesting Framework
• simple mechanism for sharing metadata
records
• records shared over HTTP...
• ... as XML (using XML Schema)
• client can ask metadata server for
• all records
• all records modified in last ‘n’ days
• info about sets, formats, etc.
• See <http://www.openarchives.org/>
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Alerting
Content
Web
Web
Web
Web
RSS
Authentication
Authorisation
Aggregator
Collect’n Desc
Portal
Service Desc
Email
HTTP
End-user
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RSS
• Rich/RDF Site Summary
• XML application for syndicated news feeds
• pointers and simple descriptions of news
items (not the items themselves)
• has been transitioned to more generic
RDF/XML application (RSS 1.0)
• no querying - just regular ‘gathering’ of
RSS file
http://www.ukoln.ac.uk/metadata/rssxpress/
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request, access
How does the DNER help us access
content?
Resource identification
• discover phase results in metadata about
a resource that may include its identifier
or a locator
• for Web resources a URL is common
• identifier is persistent
• locator also needs to be persistent
• enable lecturers to embed it into learning
resources
• enable students to embed it into multimedia
essays
• enable people to cite it
23
Identifiers/locators
• also need to think about what is
identified...?
• the resource (e.g. an image)
• the resource in context (e.g. image
embedded into VADS page)
• metadata about the resource (e.g. description
of image from VADS or subject gateway)
• probably need to identify all of these
• need guidelines on good practice for use
of URLs
• investigate use of DOIs
24
Resolving identifiers
• may need to resolve the metadata,
identifier or locator into information about
how to request a particular instance of the
resource
• ‘locate’ part of detail phase provides
resolution using resolvers
• resolvers find appropriate copy
• location is context sensitive - need to know
who end-user is, where they are and what they
have access to
25
• may be best carried out locally to enduser?
OpenURL
• metadata, identifier or locator forms a
‘citation’ for the resource
• OpenURL provides mechanism for
encoding citation for a resource as a URL
• OpenURL = baseURL + description
• baseURL provides location of a ‘resolver’
• description is either a global identifier
(e.g. a DOI or ISBN) or a description (a
citation) or mixture
• http://sfx.bath.ac.uk/sfxmenu?genre=book
&isbn=1234-5678
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Locate and identifiers
Web
resource
Book
Journal
issue
Article
Discovery services
Discover
URI
DOI
ISBN
Citation/metadata
OpenURL or Z39.50
request
Locate
Locate services
(resolvers)
Resource
URL
Request
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Persistent ‘identifiers’
- context independent
Delivery service URL
or
Resource URL
Transient ‘locators’
- context sensitive
OpenURL resolver
Content
Delivery
service
Authentication
Authorisation
Collect’n Desc
Service Desc
OpenURL
Portal
Resolver
HTTP
End-user
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DNER shared services
• authentication
• authorisation/profiling
• collection description
• service description
• resolution
• user preferences
• thesauri/terminology
• metadata registry
• (ratings, terms & conditions)
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key
desirable
Summary
provision
content
middleware
shared
services
m2m
interfaces
portals
presentation
30
brokers
and
aggregators
fusion