eLib Technical Issues Concertation Day: Introduction and Document Formats Brian Kelly UK Web Focus UKOLN, University of Bath, Bath B.Kelly@ukoln.ac.uk http://www.ukoln.ac.uk/
Contents• Introduction • About The Presenter • UK Web Focus• Document Formats • HTML • Style Sheets • SGML • Acrobat• Content Negotiation• Issues
About The PresenterBrian Kelly: • Involved with WWW since Jan 1993 (Leeds University first to run institutional WWW service) • Attended first WWW Conference (CERN, May 94) • Author of SIMA handbook on Running A WWW Service • Member of programme and awards committee for 5th WWW Conference • Senior trainer for Netskills (Oct 95-96)
UK Web FocusUK Web Focus: • Responsible for: – Technology watch – Dissemination of information – WWW coordination within UK HE community – Represents JISC on W3C • Based at UKOLN, University of Bath • Brian Kelly appointed from 1st Nov 1996
HTML DevelopmentsHTML 2.0 • First widely used HTML DTDHTML + / HTML 3.0 • Plans for greater functionalityNetscape / Microsoft HTML Extensions • Added new functionality • Lose browser independence • Architectural flawsHTML 3.2 • New proposed specification (agreed by W3C, Netscape, Microsoft, …)
Formatting TagsNetscape and Microsoft introduced newformatting tagsMany are:• Architecturally flawed• Contravene spirit of SGML (define Imagine a large Web site, document structure, with house style defined in every document. not appearance)• Maintenance Consider maintenance load when changing problems house style.
FramesFrames are another example of a Netscapeextension, but with architectural flaws: • Bundles user interface information with document content (cf. style sheets) • Lack of control by end user • Not liked by many users (e.g. users of low resolution PCs, PDAs, …) • Not possible to distinguish between documents with and without framesNote that W3C propose implementation offrames using style sheets - seehttp://www.w3.org/pub/WWW/TR/NOTE-layout.html
Content Negotiation In HTTP it is (or will be) possible for clients and servers to negotiate over preferred document formats (and HTML features?)Client ServerGive me the file welcome Voilá.I prefer the Frenchversion.Give me the image Here’s the filelogo.gif My PC only logo.16col.gifsupports 16 colours.Give me welcome My Here it is.browser supports tables,but not frames
SGMLIs the future for HTML the integration withPanorama is anexample of anSGML DTD-awarebrowser.
Adobe AcrobatWith Adobe Acrobat:• Greater control over layout• Hypertext links are possible• Netscape plugins availableBut• Lose document See http://www.adobe.com/ structure• Proprietary
IssuesIssues which WWW developers will have toaddress include: • Software tools (e.g. style sheet editors) • Deployment of new features (e.g. browsers supporting style sheets) • Use of not-standard features (e.g. frames, other proprietary tags)