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New Standards on the Web

Brian Kelly Email Address

UK Web Focus B.Kelly@ukoln.ac.uk

UKOLN URL

University of Bath http://www.ukoln.ac.uk/

UKOLN is funded by the British Library Research and Innovation Centre, the Joint Information Systems Committee of the Higher Education Funding Councils, as well as by project funding from the JISC’s Electronic Libraries Programme and the European Union. UKOLN also receives support from the University of Bath where it is based.

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Contents

• Introduction

• Web Standards Overview

• Web Standards:• Data Formats• Transport• Addressing

• Metadata

• Deployment Issues

Aims of Talk• To give brief overview

of web architecture• To describe

developments to web standards (especially those relevant to library community)

• To briefly address implementation models

Due to lack of time, talk will not cover some new standards, such as:

• Graphics• Multimedia• e-commerce

Aims of Talk• To give brief overview

of web architecture• To describe

developments to web standards (especially those relevant to library community)

• To briefly address implementation models

Due to lack of time, talk will not cover some new standards, such as:

• Graphics• Multimedia• e-commerce

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Standardisation

W3C• Produces W3C

Recommendations on Web protocols

• Managed approach to developments

• Protocols initially developed by W3C members

• Decisions made by W3C, influenced by member and public review

IETF• Produces Internet

Drafts on Internet protocols• Bottom-up approach to developments• Protocols developed by

interested individuals• "Rough consensus and working

code"

ISO• Produces ISO

Standards• Can be slow moving

and bureaucratic• Produce robust

standards

Proprietary• De facto standards• Often initially appealing

(cf PowerPoint, PDF)• May emerge as

standards

PNGHTMLZ39.50Java?

PNGHTMLZ39.50Java?

PNGHTMLHTTP

PNGHTMLHTTP

HTTPURNwhois++

HTTPURNwhois++

HTML extensionsPDF and Java?

HTML extensionsPDF and Java?

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The Web Vision

Tim Berners-Lee's vision for the Web:• Evolvability is critical • Automation of information management:

If a decision can be made by machine, it should• All structured data formats should be based on XML• Migrate HTML to XML• All logical assertions to map onto RDF model• All metadata to use RDF

See keynote talk at WWW 7 conference at <URL: http://www.w3.org/Talks/1998/0415-Evolvability/slide1-1.htm>

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HTML 4.0, CSS 2.0 and DOMHTML 4.0 used in conjunction with CSS 2.0 (Cascading Style Sheets) and the DOM provides an architecturally pure, 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

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 Limitations

HTML 4.0 / CSS 2.0 have limitations:• Difficulties in introducing new elements

– Time-consuming standardisation process (<ABBREV>)

– Dictated by browser vendor (<BLINK>, <MARQUEE>)

• Area may be inappropriate for standarisation:– Covers specialist area (maths, music, ...)– Application-specific (<STUD-NUM>)

• 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 of evolvability• Arbitrary elements can be defined (<STUDENT-NUMBER>, <PART-NO>, etc)

• Agreement achieved quickly - XML 1.0 became W3C Recommendation in Feb 1998

• Support from industry (SGML vendors, Microsoft, etc.)

• HTML is being described in HTML - see <URL: http://www.w3.org/TR/WD-html-in-xml/>

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XML Support

XML support:• Can be provided at backend• (Partial) XML support in IE 5• Also in Netscape 5?

XML document with no style sheet - XML tree displayed

XML document with no style sheet - XML tree displayed

XML document with style sheetXML document with style sheet

http://www.xml.com/1999/03/ie5/first-x.xml

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XLink, XPointer and XSL

XLink will provide sophisticated hyperlinking missing in HTML:

• Links that lead user to multiple destinations• Bidirectional links• Links with special behaviours:

– Expand-in-place / Replace / Create new window– Link on load / Link on user action

• Link databases

XPointer will provide access to arbitrary portions of XML resource

XSL stylesheet language will provide extensibility and transformation facilities (e.g. create a table of contents)

EnglandFrance

<commentary xml:link="extended" inline="false"> <locator href="smith2.1" role="Essay"/> <locator href="jones1.4" role="Rebuttal"/> <locator href="robin3.2" role="Comparison"/> </commentary>

<commentary xml:link="extended" inline="false"> <locator href="smith2.1" role="Essay"/> <locator href="jones1.4" role="Rebuttal"/> <locator href="robin3.2" role="Comparison"/> </commentary>

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Addressing

URLs 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)

Solutions:• Unique identifiers possible, but resolution difficult• Solutions include DOIs, PURLs, etc. • "URLs don’t' break - people break them". Think

about URL persistency and naming guidelines

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TransportHTTP/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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MetadataMetadata - the missing architectural component from the initial implementation of the web

Metadata - RDF

PICS, TCN,

MCF, DSig,

DC,...

AddressingURL

Data formatHTML

TransportHTTP

Metadata Needs:• Resource discovery• Content filtering• Authentication• Improved navigation• Multiple format support• Rights management

Metadata Needs:• Resource discovery• Content filtering• Authentication• Improved navigation• Multiple format support• Rights management

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Metadata Examples

DSig (Digital Signatures initiative):• Key component for providing trust on the web• DSig 2.0 will be based on RDF and will support signed

assertion:– This page is from the University of Bath– This page is a legally-binding list of courses

provided by the University

P3P (Platform for Privacy Preferences):• Developing methods for exchanging Privacy Practices

of Web sites and user

Note that discussions about additional rights management metadata are currently taking place

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RDF

RDF (Resource Description Framework):• Highlight of WWW 7 conference

• Provides a metadata framework ("machine understandable metadata for the web")

• Based on ideas from content rating (PICS), resource discovery (Dublin Core) and site mapping (MCF)

• Applications include:– cataloging resources – resource discovery– electronic commerce – intelligent agents– digital signatures – content rating– intellectual property rights – privacy

• See <URL: http://www.w3.org/Talks/1998/0417-WWW7-RDF>

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RDF ModelRDF:

• Based on a formal data model (direct label graphs)

• Syntax for interchange of data

• Schema model

Resource ValuePropertyType

Property

page.html £0.05Cost

23-Mar-99

ValidUntil

RDF Data Model

page.html £0.05

23-Mar-99

Property

Cost

InstanceOf

ValidUntil

ValuePropObj

Cost

PropName

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Browser Support for RDF

Mozilla (Netscape's source code release) provides support for RDF.

Mozilla supports site maps in RDF, as well as bookmarks and history lists

See Netscape's or HotWired home page for a link to the RDF file.

Trusted 3rd

Party Metadata

Embedded Metadata

e.g. sitemaps

Image from http://purl.oclc.org/net/eric/talks/www7/devday/Image from http://purl.oclc.org/net/eric/talks/www7/devday/

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RDF Conclusion

RDF is a general-purpose framework RDF provides structured, machine-

understandable metadata for the Web Metadata vocabularies can be developed

without central coordination RDF Schemas describe the meaning of

each property name Signed RDF is the basis for trust

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Deployment Issues

How can new technologies be deployed?• Expect (hope) everyone will move to

new browsers• Use technologies in backwards-

compatible manner• Develop additional protocols e.g.

– Transparent Content Negotiation

– CC/PP

• User-Agent Negotiation• Use of proxy intermediaries

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Intermediaries can provide functionality not available at client:

• DOI support• XML support / format conversion• Authentication

Intermediaries can provide functionality not available at client:

• DOI support• XML support / format conversion• Authentication

Deployment IssuesMore sophisticated deployment techniques can be adopted to overcome deficiencies in simple model

HTML resource

browserWeb server

Web server simply sends file to clientFile contains redundant information (for old browsers) plus client interrogation support

HTML / XML /

databaseresource browser

Server proxy

Client proxy

Original Model

Sophisticated Model

IntelligentWeb server

Example of an intermediary

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Conclusions

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 is big growth area• Intermediaries may have a role to play in deploying

standards-based solutions• Intelligent servers likely to be important