standards for hybrid libraries
TRANSCRIPT
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Standards For Hybr id Lib rar ies:
Web Standards
Brian Kelly
UK Web Focus
UKOLN
University of Bath
Bath, BA2 7AY
UKOLN is funded by the Library and Information Commission, the Joint
Information Systems Committee (JISC) of the Higher 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.
http://www.ukoln.ac.uk/
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Contents
Introduction Background To The Web Architecture:
Addressing
Data Format
Transfer
Metadata
Conclusions
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Standardisat ionCommunity
Library groups Cultural Heritage
Government
W3C Produces W3C
Recommendat ions
Managed approach
Protocols initially
developed by
W3C members Decisions made by
W3C, influenced by
member &
public
review
IETF
Produces InternetDrafts on Internet protocols
Bottom-up approach to developments
Protocols developed by
interested individuals
"Rough consensus and workingcode"
Formal Formal international/
national standards
processes
ISO, CEN, NISO,ECMA, ANSI, BSI
Can be slow-moving
and bureaucratic
Produce robust
standards
PNG
HTML
HTTP
HTTP
URN
whois++
Proprietary
De facto standards Often initially
appealing (cf GIF,
PowerPoint, PDF)
May emerge as
standards
23950
PNG
HTMLJava?
Relevant
Bodies
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Background to the Web
The web was initially very successful due toits simplicity
Client
Mosiac
Netscape
IEHTML
Server
CERN
ApacheIIS
Give me foo.html
from www.bath.ac.uk
Here it is
The web is based on three key architectural components:Data Format:
HTML (HyperText Markup Language)
Addressing:
URLs (Uniform Resource Locators)
Transport:
HTTP (Hypertext Transfer Protocol)
HTML
URLs
HTTP
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Prob lems With the Web
Although the web has been successful, thereare problems: Performance - the web is too slow
Resource discovery - lack of a metadataarchitecture
HTMLs lack of arbitrary structure
Accessibility - difficulties of accessing informationby visually impaired, people using PDAs, etc.
Functionality - difficult to deploy new applications
on the web Addressing
etc.
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So lut ions (Today)
HTML 4.0 used in conjunction with CSS 2.0 (Cascading
Style Sheets) and the DOM provides an architecturallypure, yet functionally rich environment
HTML 4.0 - W3C-Rec Improved forms
Hooks for stylesheets Hooks for scripting
languages
Table enhancements
Better printing
CSS 2.0 - W3C-Rec Support for all HTML
formatting Positioning of HTML
elements
Multiple media support
Problems
Changes during CSS development
Netscape & IE incompatibilities
Continued use of browsers with
known bugs
DOM - W3C-Rec Document Object Model
Hooks for scripting
languages
Permits changes to
HTML & CSS properties
and content
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HTML's L im itat ions
HTML 4.0 / CSS 2.0 have limitations: Difficulties in introducing new elements Time-consuming standardisation process
()
Dictated by browser vendor(, )
Area may be inappropriate for standarisation:
Covers specialist area (maths, music, ...)
Application-specific ()
HTML is a display (output) format
HTML's lack of arbitrary structure limits functionality: Find all memos copied to John Smith
How many unique tracks on Jackson Browne CDs
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XML
XML: Extensible Markup Language A lightweight SGML designed for network use
Addresses HTML's lack ofevolvability
Arbitrary elements can be defined (, , etc)
Agreement achieved quickly - XML 1.0 becameW3C Recommendation in Feb 1998
Forms the basis of B2B applications
Support from industry (SGML vendors,Microsoft, etc.)
Support in Netscape 5 and IE 5
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XML Dep loyment
Ariadne issue 15 has articleon "What Is XML?"
Describes how XML
support can be provided:
Natively by new browsers
Back end conversion
of XML - HTML
Client-side conversion
of XML - HTML / CSS
Java rendering of XMLExamples ofintermediaries
See http://www.ariadne.ac.uk/issue15/what-is/
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XHTML
XHTML:
an XML representation of HTML
Issues: Documents must be well-formed
Tags in lowercase Quote attributes:
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Namespaces and Linking
XML NamespacesWhat if an XML document contains a forthe document and a for the name of abook?
XML Namespaces enable such clashes to be
resolvedThe naming conventions are defined at a URL
XSL stylesheet language will provide extensibility andtransformation facilities (e.g. create a table of contents
orcreate metadata from structured data)
XLink and XPointershould provide richer hyperlinkingmechanisms in the future
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Add ress ing (Prob lems)
URLs (e.g. http://www.bris-poly.ac.uk/depts/music/) have limitations:
Lack of long-term persistency
Organisation changes name
Department shut down or merged
Directory structure reorganised
Inability to support multiple versions of
resources (mirroring)ISBN/ISSN also problematic:
Not tied to the work
Nor to the item at hand
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Add ress ing (Solut ions )
PURLs (Persistent URLs): Provide single level of redirection
DOIs (Document Object Identifiers):
Proposed by publishing industry as asolution
Aimed at supporting rights ownership
Business model needed
Do two copies of a digital object get
separate DOIs?
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Transport
HTTP/0.9 and HTTP/1.0: Design flaws and implementation problems
HTTP/1.1: Addresses some of these problems
60% server support
Performance benefits! (60% packet traffic reduction) Is acting as fire-fighter
Not sufficiently flexible or extensible
HTTP/NG: Radical redesign using object-oriented technologies
Undergoing trials
Gradual transition (using proxies)
Integration of application (distributed searching?)
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Metadata
Metadata - the missing architectural componentfrom the initial implementationof the web
Metadata Needs: Resource discovery Content filtering
Authentication
Improved navigation
Multiple format support
Rights management
Addressing
URL
Data format
HTML
Transport
HTTP
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RDF
RDF - the metadata
framework Based on a formal
data model (direct
label graphs)
Syntax for interchangeof data
Schema model
page.html 0.05Cost
11-May-98
ValidUntil
Resource ValuePropertyType
Property
RDF Data Model
page.html 0.05
11-May-98
Property
Cost
InstanceOf
ValidUntil
Value
PropObj
Cost
PropName
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Conclus ions
To conclude: Standards are important, especially for national
initiatives and other large-scale services
Proprietary solutions are often tempting because:
They are available They are often well-marketed and well-supported
They may become standardised
Solutions based on standards may not be properly
supported by applications
Metadata and structured data formats are big growthareas
Deployment of new standards is an important
question