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trip report from the ninth World Wide Web conference in amsterdam, the netherlandsthursday 18-may-2000: third day |
home - keynote: "Cyberspace's Constitution" - W3C track: DOM - W3C track: CSS - W3C track: XSL and XSLT
lawrence lessig started with a quote he heard recently at another conference:"keep the government out - and provide a platform for patents" The basic idea of the Internet was e2e (end-to-end) and the network in-between was dumb and had no control over the applications. But today, the network operators try to gain control over which applications run. lawrence lessig warned that private companies will control the Internet soon if we continue to let the big network operators play their games. he thinks that the government needs at least some control to insure free access to all applications for everyone. it was an entertaining but yet frightening talk and i'm afraid he could be right one day ...
the Document Object Model is a standards API to access and manipulate the content of documents. it provides:
- language and platform independency
- freedom of the underlaying structure
- support for small as well as huge documents
intended for: HTML, CSS, scripting and XML
DOM level 1 covers navigation and manipulation of structure and content of a document:
- XML 1.0 (except DTD)
- HTML V4.0
- it became a W3C recommendation in october 1998
DOM level 2 addresses:
- namespace support
- CSS object model
- user and application event model
- traversal
- range
- it became a W3C candidate recommendation on may 10, 2000
DOM implementations are available in Java, ECMAScript, C, C++, PLSQL, COM, Perl, Python, Delphin etc.
DOM level 3 should support:
- load and save
- content models and validation
- views and formatting
- new events functionality
- new core functionality
- it is still under consideration, see working draft for details
future levels may support:
- XPath (may be included in level 3)
- transactions, batching of operations
- XSLT style sheets
- more ...
extensions of DOM are MathML, SVG, SMIL animation
this talk is available on the Web
basic idea: separate structure and style from content. this will:
- make it easier to maintain documents
- increase accessibility
today, the major browsers support up to 99% of CSS1. authors can rely on CSS1 by the end of the year 2000. style sheets provide not only a convenient means for authors to apply designs (or styles) to documents, but also enable users to apply their own styles in order to support their preferences.
from CSS2 to CSS3: modularized to make it smaller and add new features:
- vertical text
- color profiles for images (from SVG)
- in-line block
- page numbering and cross references
- opacity (semi-transparent boxes)
- columns
- more system colors, fonts and user interface features
- support for SVG, ACSS (aural style sheets), Math, BECSS (behavior extensions style sheets)
modularization will reduce the size of CSS, but some modules may depend on other modules. there will also be media specific modules. see the CSS section of the W3C website for details.
XSL stands for eXtensible Stylesheet Language, a means to
- support browsing, printing and aural browsing
- format highly structured documents (XML)
- performing complex publication tasks, such as table of contents, indexes, reports etc.
- support accessibility and internationalization
- XSL is written in XML
during the first step of the formatting process, the document source (XML) will be combined with XSL through a transformation engine. in a second step, the output of step one will be processed by a formatter, the result is the formatted document.
XSLT is a transformation language, it is based on
- XPath: an expression language for addressing parts of an XML document
- FO (Formatting Objects): a vocabulary of formatting objects with their associated format properties
XSLT uses XPath which in turn uses FO.
this is a simple example:
<xsl:template match="Title"> <H1> <xsl:apply-templates/> </H1> </xsl:template>XSL usage:
- format XML documents by generating FOs
- generate HTML or XHTML from XML
- transform XML documents into other XML documents
- generate text representation from XML documents
XSL may be used on the server-side or on the client- side but it is not intended to send FOs over the wire. it is supported by 4XSLT, IE5, iXSLT, LotusXSL and many more. XSL is not intended to replace CSS but provides functionality beyond that of CSS (CSS is simpler to learn and use). both are based on formatting models and properties and values. features that are available in XSL, but not in CSS include:
- finer control by additional properties
- expressions
- more sophisticated pagination control
status: XSL 1.0 will become a W3C recommendation soon, see working draft for details.
this trip report was written on a Vadem Clio C-1050 running Windows CE with Pocket Word. It was then transferred to a DELL Latitude notebook and modified as needed. this document is supposed to be HTML V4.0 compliant.