Download HTML Is Dead! A Web Standards Update

HTML Is Dead!
A Web Standards Update
Brian Kelly
UK Web Focus
UKOLN
University of Bath
Bath
Email
[email protected]
URL
http://www.ukoln.ac.uk/
UKOLN is supported by:
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Contents
• Introduction
• Standards
• The Original Web
Architecture
• Architectural
Developments
• Deployment Issues
• Discussion
Aims of Talk
• To give brief overview
of Web architecture
• To describe
developments to Web
standards
• To briefly address
implementation
models
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Standards
Standards in an Educational /
Research Context
Standards are important in a public sector
context (e.g. education, research, central &
local government, ...) context to:
•
•
•
•
•
•
Ensure widespread access to resources
Enables resources to be reused and repurposed
Ensure scholarly resources can be preserved
Address accountability of public funding
Minimise resource costs for upgrading systems
Provide universal access to resources (cf
disability legislation)
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Standards
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Standards
Before the Web
Access to resources typically required use of software
vendor’s software – which was only available on limited
no. of platforms. Often the software would be licensed.
The goal of the Web was to provide universal access to
resources. Who could argue with this goal?
Need for standards to provide:
• Platform and application independence
• Avoidance of patented technologies
• Flexibility and architectural integrity
• Long-term access to data
Ideally look at standards first, then find applications
which support the standards. However it can be difficult
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Standards
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Standards and the Web
Proprietary
HTML
• De facto standards
extensions
PDF and Java? • Often initially appealing
(cf PowerPoint, PDF)
PNG
•
May
emerge
as
W3C
HTML
ISO
standards
• Produces W3C
• Produces ISO Z39.50
Recommendations
Java
Standards
on Web protocols
• Can be slow moving
• Managed approach to
and bureaucratic
developments
• Produce robust
• Protocols initially
standards
IETF
developed by
• Produces Internet
W3C members
Drafts on Internet protocols
• Decisions made by
• Bottom-up approach to developments
W3C, informed
HTTP
• Protocols may be developed
by member &
URN
by interested individuals
public review
• "Rough consensus and working whois++
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HTML,
PNG,
… information
code"
Standards
The Case For W3C Standards
Why use open standards developed by the
W3C? Why not leave it to the marketplace?
 W3C’s open standards have been developed in
an open environment, with the aim of achieving
platform and application independency
 Commercial companies develop proprietary
formats in order to maximise their profits and
dividends to shareholders
 W3C’s open standards have been developed to
interoperate with each other according to W3C’s
design vision
 Commercial companies typically develop
proprietary formats in isolation, or along the lines
of a company vision
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Standards
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
GIF vs PNG
Applications: software
products used to implement
systems
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
Apache / IIS
Development vs. Migration costs
FrontPage / Dreamweaver
Use of in-house expertise
Oracle / SQLServer
In-house vs. out-sourced
ColdFusion
vs ASP
Licensed vs. open source
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Standards
GIF
As an example of the dangers of use of proprietary
solutions, consider the GIF file format:
• Unisys announce that they hold patent to
compression algorithm used in GIF images and
users of GIF will have to pay
• Following much debate, Unisys require payment
for licence from software developers - and also
for end users of unlicensed software ($5,000!)
• Web community responds with PNG format
• See <http://burnallgifs.org/>
WARNING:
• There is no guarantee that payment will not be
required for proprietary file formats which are
currently free
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How Does The Web Work?
The Web has three fundamental concepts:
• URLs: addresses of resources
• HTTP: dialogue between client and server
• HTML: format of resources
1 User clicks on link to the address (URL)
http://www.netsoft.com/hello.html
Web Browser
The Netsoft
home page
Welcome to
Netsoft
2 Browser converts link to HTTP command (METHOD):
Connect to computer at www.netsoft.com
GET /hello.html
3 Remote computer sends file
Web
server
4 Local
computer
displays
HTML
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<HTML>
<TITLE>Welcome</TITLE>..
<P>The <A HREF=“…”>
Netsoft</A> home page</P>
file
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Data Formats
Approaches To HTML
Emphasis on managing HTML resources inappropriate:
• HTML is an output format, which cannot easily be
reused (e.g. WAP, e-Books, etc.)
• Need to manage HTML fragments (only partly
achievable with SSIs)
• Need to manage collections of resources
• Need to have single master source of data
• Need to support new developments such as
personalisation
• Difficult to integrate with new formats
Issues
• Should we stop giving HTML training courses?
• Should
weinstop
authoring tools?
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Data Formats
XML
XML:
•
•
•
•
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 latest versions of Web browsers
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Data Formats
XML Concepts (1)
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
<p> and <P> are different
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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Data Formats
XML Concepts (2)
XML Schemas
• Allow constraints to be applied on XML attributes
• Express shared vocabularies and allow machines
to carry out rules made by people
• Richer than DTDs
• See <http://www.w3.org/XML/Schema>
XSLT
• A language for transforming XML from one DTD
to another, or to another format (e.g. PDF)
• Written in XML
• Knows about XML (e.g. tree structures, etc.)
• See <http://www.xslt.com/>
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Data Formats
XML Concepts (3)
England
XLink sophisticated hyperlinking:
France
• Links that allow you to choose multiple destinations
• Bidirectional links
• Links with special behaviours:
• Expand-in-place / Replace / Create new window
• Link on load / Link on user action
• Link databases
• See <http://www.xml.com/pub/a/2000/09/xlink/>
XPointer
• Provides access to arbitrary portions of XML
resource
• See <http://www.w3.org/TR/xptr/>
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Data Formats
Getting to XML With XHTML
XHTML:
• 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 >)
<img src="logo" ... />
• 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/>
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Data Formats
CSS
CSS:
• Cascading Style Sheets
• XHTML/XML defines structure, CSS describes
the appearance
• CSS 1.0 and 2.0 now W3C recommendations
• CSS 3.0 in preparation (modularised)
• We should be using CSS:




Part of architecture
Ease of maintenance
Becoming much richer
Accessibility
• See <http://www.w3c.org/Style/CSS/>
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Data Formats
SVG
SVG:
• Scalable Vector Graphics
• A language for describing two-dimensional
graphics in XML
• See <http://www.w3.org/Graphics/SVG/
Overview.htm8>
• Also see presentation on XML written in SVG at
<http://www.w3c.org/Talks/2001/12/
IH-Euroweb/W3CInTheWorldslide.svgz>
• WWW 2002 talk at
<http://www.w3c.org/2002/Talks/
www2002-SVG/>
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Data Formats
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Data Formats
SVG Example
http://www.karto.ethz.ch/neumann/cartography/vienna/
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Data Formats
SVG and XSLT
This example:
http://people.w3.org/maxf/ChessGML/
• Originally
written in Java
• Author
realised that
XSLT would
be easier
• Uses SVG for
chess board
and pieces
• Uses XSLT to
move pieces
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CML, SVG and XSLT
http://www.adobe.com/svg/demos/cml2svg/html/index.html
A molecule
described in
CML can be
transformed
using XSLT
into SVG,
allowing it to
be displayed
and
manipulated
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Data Formats
SMIL
SMIL:
• Synchronized Multimedia Integration
Language
• A language for authoring of interactive
audiovisual presentations
• Allows you to synchronize text, images,
audio and video in a document
• An XML Application
• See <http://www.w3c.org/AudioVideo/>
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http://www.reseau.it/smil/smilapp_en.html
SMIL Example
http://www.kevlindev.com/tutorials/
basics/animation/svg_smil/index.htm
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MathML
MathML:
• An XML
application
for maths
• Various
plugins,
dedicated
readers,
etc.
• Mozilla
renders
natively
See <http://www.mozilla.org/projects/mathml/>
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Data Formats
Modularisation
How can you:
• Include XML resources such as MathML,
ChemML, etc in XHTML documents?
• Provide a subset of XHTML features in browsers
on devices such as mobile phones, PDAs, etc.?
The answer is:
• XHTML modularisation (modularization )
• See
<http://www.w3.org/TR/xhtml-modularization/>
and
<http://www.xml.com/pub/a/2002/01/16/
xhtml-m12n.html>
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Web Standards
Part 2 –Deployment Issues
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W3C Challenges
W3C faces a number of challenges:
• Commercial acceptance (cf. browser wars):
• Software vendors may refuse to deploy new standards
• User acceptance:
• User may not use of new standards (it's too complex /
expensive, …)
• Patent issues
• Software vendors may claim patents on new standards
• Complexity
• The wide range of new standards makes deployment too
difficult
• Organisational issues
• W3C is facing too many difficulties in growth, politics, etc.
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Deployment
Architectures
Let us consider the following areas:
• Content Management
• Access (Browser support)
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Deployment
Position Today
What should we be doing today?
• Move away from creating new content in HTML
• Move to XHTML as part of the migration
• Deploying XML applications
• Storing structured information in a neutral
database
• Using a CMS to manage our content
• Deploying B2B applications to avoid human
bottleneck (such as RSS)
Note that these are aspirations. We will, of course,
be constrained by existing systems, resource
implications, vested interests, inertia, etc.
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Deployment
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The CMS To The Rescue
HTML authoring tools have limitations (as has HTML).
A CMS (Content Management System):
• Allows fragments to be managed
• Allows collections to be managed
• Allows resources to be stored in a neutral format
(backend database)
• Allows resources to be reused
• Often provides access control
• Often provides workflow processes and project
management
Issues
• CMS can be expensive
• CMS can be free but have support implications
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Browser Issues
Which approach to browser issues should you take?
Web sites should be usable to old browsers as these
are still in use and we aim to maximise access.
Therefore you should deliver HTML 3.2 / 4.0 and
avoid technologies such as JavaScript and CSS.
NOTE
Old browsers are broken and fail to
• Use of ‘clean’ HTML should
implement new technologies which
degrade gracefully
provide (a) richer functionality (b)
• XHTML is a useful transition support for new devices and (c)
better support for people with
• User-agent negotiation may
be relevant
disabilities.
QUESTION
Therefore you should use the latest
• Should organisations /
stable versions of HTML (XHTML),
community implement a
CSS, etc.
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browser policy?
Conclusions
To conclude:
• The Web has not yet stabilised
• New developments provide needed functionality or
address current limitations
• However W3C cannot guarantee that its vision will
necessarily be implemented
• There is therefore a risk and a cost in adopting new
standards
• There is also a risk in failing to adopt new
standards!
• Keeping up-to-date is therefore essential!
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Questions
Any questions?
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