standards for hybrid libraries

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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.

[email protected]

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