Transcript The Latest Web Developments

The Latest Web
Developments
Brian Kelly
UK Web Focus
UKOLN
University of Bath
Bath, BA2 7AY
UKOLN is supported by:
Email
[email protected]
URL
http://www.ukoln.ac.uk/
About Me
Brian Kelly:
• UK Web Focus – a JISC-funded post to advise HE
and FE communities on Web developments
• Based in UKOLN (UK Office for Library and
Information networking) – a small applied research
organisation in University of Bath
• Involved in Web since 1993, while working in
Computing Service at University of Leeds
• Close links with Computing Service and Library
communities
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About You
What is your involvement with the Web?
What topics would you like covered today?
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Possible Interests
XML
Web applications
File formats
Content Management Systems
Hyperlinking
Legal issues
Interests
RDF
When is it going to stabilise?
What’s happening to HTML?
Web Standards
Web browsers
Netscape or Microsoft?
Web Architectures
Web Applications
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Technologies
Web Services
Open source vs licensed apps
Contents
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Standards and the Web
The Original Web Architecture
The Problems
Architectural Developments
Metadata
New Developments
Deployment Issues
Discussion
Standards, Architectures,
Applications, Resources
This talk touches on several areas
Standards: concerned with
protocols and file formats
Open standards vs. Proprietary
HTML / XML vs. PDF
CSS / XSL vs. HTML
Applications: software
products used to implement
systems
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Apache / IIS
FrontPage / Dreamweaver
Oracle / SQLServer
ColdFusion vs ASP
Architectures: models for
implementing systems
Which standards are applicable
NT / Unix
File system / database application
HTML tools / content management
Resources: financial and staff
costs needed to implement
systems
Development vs. Migration costs
Use of in-house expertise
In-house vs. out-sourced
Licensed vs. open source
Standards
Need for standards to provide:
• Platform independence
• Application independence
• Avoidance of patented technologies
• Flexibility ("evolvability" - Tim Berners-Lee)
• Architectural integrity
• Long-term access to data
Ideally look at standards first, then find applications
which support the standards
Difficult to achieve this ideal!
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Deployment Issues
What part of the spectrum are you closest to?
Must support standards
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Go with the marketplace
I Support Standards
But:
• You probably use PowerPoint, don't you?
• Software vendors will subtly suck you into use of
proprietary features
• Home-grown solutions can be expensive (where are
all the good Perl / C programmers willing to work on
short-term contracts for a pittance in Universities?)
• Standards may not take off – remember Coloured
Book network protocols?
• Proprietary solutions may become standardised
• Standards may not yet be available (or finalised)
• Do users want standards? Will "We support
standards" conflict with "Our services are based on
user requirements"?
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I Follow The Marketplace
Good New Labour philosophy, but:
• Can you trust your software vendor?
• Will your software vendor be around in a few
years time ("I only buy Rover")
• Will your system be interoperable?
• What happens when you want to interwork
with partners or your organisation merges / is
taken over?
• What happens when you want to extend your
system beyond the limits set by your software
vendor?
IBM was the market leader in the 1970s, but lost out in the
PC revolution
What will happen if Microsoft is split in two?
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Some Difficulties
We should acknowledge some difficulties in a
standards-based approach:
• Keeping up-to-date (look at nos. of documents at
http://www.w3c.org/TR/ and size of
http://www.diffuse.org/standards.html)
•
•
•
•
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Spotting the winning standards
Implementing the standard in a timely way
Dealing with the problems of the software vendor
Resources!
Standardisation
Other
• Standards bodies
such as ECMA
• Community groups
which can agree on,
say, profiles
HTML
Proprietary
extensions
• De facto standards
PDF and Java?
• Often initially appealing
W3C
(cf PowerPoint)
PNG
• Produces W3C
• May emerge as
HTML
ISO
Recommendations
standards
• Produces ISO Z39.50
on Web protocols
Java?
Standards
• Managed approach to
• Can be slow moving
developments
and bureaucratic
• Protocols initially
• Produce robust
IETF
developed by
standards
W3C members
• Produces Internet
• Decisions made by
Drafts on Internet protocols
W3C, influenced by
• Bottom-up approach to developments
member and public
• Protocols developed by
HTTP
review
interested
individuals
PNG
URN
•
"Rough
consensus
and
working
HTML
whois++
code"
HTTP
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World Wide Web Consortium
Much of the development of Web standards
is being coordinated by the W3C:
W3C (World Wide Web Consortium):
• International consortium, with headquarters
at MIT, INRIA and Keio University (Japan)
• Coordinates development of web protocols
• Four domains:
• Architecture
• User Interface
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• Technology & Society
• Web Accessibility
The Web Vision
Tim Berners-Lee's vision for the Web:
• 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
A useful overview of Tim Berners-Lee's vision for the
Web is given in his book Weaving The Web.
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How Does The Web Work?
The Web has 3 fundamental concepts:
• URLs: addresses of resources
• HTTP: dialogue between client and server
• HTML: format of resources
The Netsoft
home page
Welcome to
Netsoft
Web Browser
(client)
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1 User clicks on link to the address (URL)
http://www.netsoft.com/hello.html
2 Browser converts link to HTTP command (METHOD):
Connect to computer at www.netsoft.com
GET /hello.html
3 Remote computer sends file
<HTML>
<TITLE>Welcome</TITLE>..
<P>Welcome to <B>Netsoft
</B>
4 Local computer displays HTML file
Web
server
Web Protocols
Web initially based on three
simple protocols:
Data Format
HTML
Addressing Transport
URL
HTTP
• Data Formats
HTML (HyperText Markup Language)
provides the data format for native documents
• Addressing
URLs (Uniform Resource Locator) provides an
addressing mechanism for web resources
• Transport
HTTP (HyperText Transfer Protocol) defines
transfer of resources between client and server
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HTML 4.0, CSS 2.0 & DOM 1.0
HTML 4.0 used in conjunction with CSS 2.0
(Cascading Style Sheets) and DOM 1.0 provides an
architecturally pure, yet functionally rich environment
HTML 4.0
• Improved forms
• Hooks for stylesheets
• Hooks for scripting
languages
• Table enhancements
• Better printing
CSS Problems
• Changes during CSS development
• Netscape & IE incompatibilities
• Continued use of browsers with
known bugs
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CSS 2.0
• Support for all HTML
formatting
• Positioning of HTML
elements
• Multiple media support
DOM 1.0
• Document Object Model
• Hooks for scripting
languages
• Permits changes to
HTML & CSS properties
and content
CSS
CSS:
• Cascading Style Sheets
• An open standard
developed by W3C
• Separates document
structure (defined in
HTML/XML) from the
appearance
• Makes maintenance of
resources much easier
<link rel="style" src="sty.css"
<h1>Heading</h1>
<p>…</p>
Imagine 10,000 HTML files ..
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http://www.w3c.org/Style/CSS/
body {background: blue;}
h1: {font-family: arial}
p: {font-family: times;
text-align: justify}
With 1 CSS file
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:
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– Find all memos copied to John Smith
– How many unique tracks on Spice Girls CDs
XML
XML:
•
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•
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Extensible Markup Language
A lightweight SGML designed for network use
Addresses HTML's lack of evolvability
Arbitrary elements can be defined (<STUDENTNUMBER>, <PART-NO>, etc)
• Agreement achieved quickly - XML 1.0 became
W3C Recommendation in Feb 1998
• Support from industry (SGML vendors, Microsoft,
etc.)
• Support in Netscape 6 (?) and IE 5
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XML Concepts
Well-formed XML resources:
Make end-tags explicit: <li>...</li>
Make empty elements explicit: <img ... />
Quote attributes <img src="logo.gif" height="20"
Use consistent upper/lower case
Valid XML resources:
Need DTD
XML Namespaces:
Mechanism for ensuring unique XML elements:
<?xml:namespace ns="http://foo.org/
1998-001" prefix="i">
<p>Insert <i:PART>M-471</i:PART></p>
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More XML Developments
Momentum behind XML is driving additional
standardisation developments
XML Path
A language for addressing parts of an XML document,
designed to be used by XSLT and XPointer
XML Schemas (Ii)
Defining the nature of XML schemas and their component
parts
XSLT
A language for transforming XML documents into other
XML documents
…
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XHTML
XHTML:
• Extensible Hypertext Markup Language
• HTML represented in XML
• Some small changes to HTML:
– Elements in lowercase (<p> not <P>)
– Attributes must be quoted (<img src="logo" height="50">
– Elements must be closed (< p >..</ p >)
– Empty elements must be closed (<img src="logo" . />)
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• Gain benefits from XML
• Tools available (e.g. HTML-Kit from
http://www.chami.com/html-kit/)
• See <http://www.webreference.com/xml/
column6/>, <http://groups.yahoo.com/
group/XHTML-L/> and <http://www.ariadne.ac.uk/
issue27/web-focus/>
Transport
HTTP/0.9 and HTTP/1.0:
 Design flaws and implementation problems
HTTP/1.1:


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

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:




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Radical redesign using object-oriented technologies
Undergoing trials
Gradual transition (using proxies)
Moving slowly
Addressing
URLs (e.g. http://www.bristol-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)
URNs (Uniform Resource Names):
• Proposed as solution
• Difficult to implement (no W3C activity in this
area)
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Addressing - Solutions
PURLs (Persistent URLs):
• Provide single level of redirection
DOIs (Digital Object Identifiers):
• Proposed by publishing industry as a solution
• Aimed at supporting rights ownership
• Business model needed
OpenURLs
• Address mirroring issues
Pragmatic Solution:
• URLs don't break - people break them
• Design URLs to have long life-span
Further information:
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<URL: http://www.ukoln.ac.uk/metadata/resources/urn/>
<URL: http://www.w3.org/Provider/Style/URI>
Metadata
Metadata - the missing architectural component from
the initial implementation of the Web
Addressing
URL
Metadata Needs:
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•
•
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Resource discovery
Content filtering
Authentication
Improved navigation
Multiple format support
New devices
Rights management
Transport Data format
HTTP
HTML
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)
• Based on a formal data model (direct label graphs)
• Applications include:
– cataloging resources
– electronic commerce
– intellectual property rights
– resource discovery
– intelligent agents
– privacy
• See <URL: http://www.w3.org/
Talks/1998/0417-WWW7-RDF>
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RSS – An RDF Application
RSS (Rich Site
Summary):
• Now an RDF
application
• Used for news feeds
• Of interest to JISC
(DNER architecture)
• Lightweight
approach that we
should be
investigating
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See example of an RSS authoring tool and parser at
<http://rssxpress.ukoln.ac.uk/>. Note this service
uses CGI – a JavaScript solution is also being developed.
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
But:
• Is RDF too complex?
• Will it gain acceptance in the market place?
The jury is till out
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Other Web Developments
Many Web standards developments are taking
place outside W3C:
• UDDI (Universal Description, Discovery, and
Integration) – a way of describing Web services in a
machine readable way to facilitate location of
services by agents.
See <http://www.uddi.org/>
• Biztalk – a framework for developing XML
schemas for B2B applications.
See <http://www.biztalk.org/>
• SOAP (Simple Object Access Protocol) - an XML
protocol for exchange of information
See <http://www.w3.org/TR/SOAP>
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New Web Areas
Initially the Web provided:
• An open environment for
• sharing information
And aimed to:
• provide a rich publishing and collaborative
environment
The Web is now:
• Widely used in closed environments (Intranets and
Extranets, for ecommerce, etc.)
• Addressing the missing components from the
original architecture
• Addressing universally by providing the
infrastructure for support of new devices
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E-commerce
E-commerce:
• Requires trust
• Requires security
• Is there a viable business
model?
Developments:
• Digital signatures
• Public Key Infrastructure
• Athens and Sparta in UK
HE
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Example 1
http://www.w3.org/Signature/
The Mobile Web
The Mobile Web:
• Much hype at present
• Have you used it?
• Is it usable on such a small screen
with slow network times?
• What about the resources need to
build a WAP site and a Web site
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Example 2
The Mobile Web Comments
Store resources in neutral format
(XML) and generate WAP and Web
XML: open storage format
XSLT: Transform XML
Ebook
format
XML
XSLT
rules
XSLT
engine
WML file
for WAP
XHTML
for Web
3G promises
multimedia and
faster networks
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Is It Worth It?
Has the Web stabilised?
• Are you thinking about WAP services?
• Will you want to (be forced to) make your Web
service accessible?
• Will you want to deploy personalised interfaces
(e.g. My.Oxford.ac.uk)
• Will your web service move from information
provision to e-business?
• Do you want your University web site to use
business-to-business (B2B) protocols to automate
transfer of link and news items to HERO?
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What Should I Do?
How can I best exploit new developments?
• Storing information in a structured format makes
subsequent redevelopment easier
• Be driven initially by standards and architectural
considerations, not by applications
• Consider use of more sophisticated web
management tools, rather than HTML authoring
tools
• An organisational standards guidelines document
(part of a Web Strategy document) may be useful
• Don't work in isolation:
– Monitor standards development (e.g. W3C)
– Listen to others in your community
– Talk and discuss issues within your community
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Authoring
Authoring Web pages:
• Was easy
• Becoming more difficult as Web becomes more
complex
• More difficult to maintain
For large Web sites there is a need for:
• More sophisticated tools e.g. content management
systems
• Tailoring content for devices?
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Architectural Models
There is a need for more intelligent software which can
process structured resources or reformat unstructured ones
HTML
resource
HTML /
XML /
database
resource
Web
server
browser
Intelligent
Web
server
Intermediaries can provide
functionality not available at client:
• DOI support
• XML support
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Web server simply sends
file to client
File contains redundant
information (for old
browsers) plus client
interrogation support
Client
proxy
browser
Server
proxy
Architectural Models –
e.g. XML Deployment
Ariadne issue 14 has
article on "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 XML
Examples of intermediaries
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See http://www.ariadne.ac.uk/issue15/what-is/
Conclusions
To conclude:
• The Web will continue to develop
• Standards are important
• 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
• There is a continual need to keep informed
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Questions
Any questions?
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