412
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A rule says "You must do it this way". A principle says "This works…and has through all remembered time". […] Anxious, inexperienced writers obey rules.
Rebellious, unschooled writers break rules.
Artists master the form.
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Robert McKee, Story
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As with writers, so with multimedia and Web designers…

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Technical definition:
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• A collection of Web pages, all of which have
URLs beginning with the same domain name
General definition:
• A collection of Web pages with a theme, a
coherent structure and a home page
413

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Totally connected
Hierarchical
Sequential
Hybrid
413–418

413–415
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Every page has a link to every other page
• Even for a small site, this structure requires a lot of links and is hard to make sense of
• May be appropriate for a small site where visitors may want to look at some or all of the pages in any order
Provide a standard navigation bar
(navbar) on each page, containing links to each of the others
• Indicate current page ("You are here")

414

415
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Most popular organization for larger sites
Home page contains pointers to a subset of other pages in the site
Each page directly accessible from home page can be considered the home page of its own sub-site
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• May contain links to home pages of sub-sub-sites, and so on
Sub-sites devoted to sub-topics of main site

415

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Essential structure is hierarchical, but there may be additional links (e.g. to each 2nd level page from every page)
Use main navbar to access major subsites plus:
• 2nd level of navbar within each sub-site
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• Hierarchical drop-down menus
Breadcrumbs popular way of showing current location in hierarchy
415–416

417–418
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May be appropriate when pages naturally form a linear sequence
• Sequence of image in an on-line gallery
• Results pages from a search engine
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• Entries in a Weblog
Usual navigation consists of Next and
Previous buttons, often augmented with links to every page in (short) sequence

417

420
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Traditional time-based media essentially linear
Digital media, linear order can be altered by scripts and in response to input from the user
• If script controls playback by computation, but without accepting input (e.g. counts frames), structure is deterministic
• To accept user input, there must be some controls to accept input
May also exhibit parallelism

420–421
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Simple loop: script attached to final frame sends playback head back to first frame
Introduction plus loop: script on final frame sends playback head to some earlier frame
(not first)
Counted loops: Script counts number of times round the loop, does something different after a certain number of loops
(e.g. stop)

422–423
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Common case: set of selections on a menu
• Menu is a single stopped frame with buttons for each menu selection
• Movie is divided into sections, each of which jumps back to the menu frame at the end
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• Script attached to each button causes a jump to the corresponding section when pressed
General branching structures built by allowing users to choose from set of alternatives for next part of movie to play next (e.g. interactive narrative)

423–425
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Flash movie clips are self-contained movies within a movie that can play back in parallel
Movie clips can be controlled by scripting
• Stopped, started, sent to a particular frame,…
Permits essentially infinite variations on playback of a finite collection of elements
Can respond to user input
• Interactive animation etc

425–426
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Heterogeneity of the Internet and its users
•
•
Pages may be viewed on any machine connected to the Internet by any connection
 Must look good at any resolution using any browser, no matter how configured, under any OS
 Download times may differ by factor up to 40
Public global network, no idea of identity of visitors
 Different cultural and educational backgrounds, levels of skills; possibly physical or cognitive disabilities

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Original design of HTML and browsers attempted to deal with heterogeneous environment:
•
• Text may reflow to accommodate to available window size
Page elements could not be positioned absolutely
Fonts could not be specified on page •
• Relative type sizes
CSS restores some control to designers, but user retains ultimate control
427

428–431
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Traditional print-based design ideas may not work on the Web
•
•
•
•
• Small screen may need scrollbars with parts of a page hidden
Fonts may be substituted
User may change type size
Brower may not support CSS properly or at all
Some people use a text-only browser

432
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Fix design – may make matters worse
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• Turn text into GIF to preserve fonts and layout – slows down page loading, leaves users with images disabled with nothing
Reduce all design to level of text-only browser
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• Page will not communicate as effectively as it could with proper design
Design for one particular configuration
•
•
Great diversity of systems and configurations
Foolish to turn away visitors who don't conform

433
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Accept that a Web page may appear differently to different users
Ensure that page remains readable and
navigable – and preferably attractive – under all circumstances

433
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Some visitors to any Web site may
• Be unable to see, or have impaired vision or defective colour vision
• Be unable to read or understand what they read very easily
• Be unable to use a mouse or keyboard, owing to injury or major disability
• Be unable to hear
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They may have to rely on assistive technology

434
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Pages must transform gracefully into a form that can be rendered by assistive technology
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• e.g. text-only for screen readers
In many countries legislation exists requiring certain classes of Web site to be accessible in this sense
Requirements based on the W3C's Web
Accessibility Initiative (WAI) guidelines

435–437
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Should supply text that can stand in for all non-textual elements of a page img and area elements: use alt attribute to specify a brief decription of the image/hotspot – displayed instead of the image in text-only browsers, read by screen readers
• If long description is needed, use longdesc to point to text-only document
Equivalents are alternatives, not replacements

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Separating structure and content from appearance (e.g. using CSS) allows page to be presented in form appropriate to user's needs
• e.g. if you use h1, h2 for headers, can use a stylesheet to format them for sighted users, an audio stylesheet to add stress for screen readers, or software can extract headings to generate an outline
Using visual markup to identify structure
(e.g. headings as p elements with special font attributes) prevents this
437

437–438
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By using absolutely positioned div elements, can create arbitrary layouts (e.g. multicolumn, call-outs, …)
If divs appear in logical order in HTML document, user agents that ignore CSS will
'see' text in its correct order
• Beware Web authoring software that may choose its own order for adding div elements to HTML
Using tables to create layouts may mislead screen readers (e.g. read straight across two columns)

438–439
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To help people with cognitive disabilities, use headings and sub-heading, bulleted and numbered lists; use one paragraph per idea
Provide navigational overview of site to help orient people who easily become confused and to allow assistive technology to isolate navigational elements
Make link text meaningful, even in isolation
• Never use click here links

439–440
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Roughly 5% of male population unable to distinguish between certain colors (usually red and green); very small number of people cannot see colors at all
Old computers, some PDAs only have black and white displays
Cannot rely on color alone to convey information
• e.g. if you use color to identify links, supplement it with some other styling
Can distinguish between confusable colors using brightness

441
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Rapidly flashing elements can trigger epileptic attacks, so avoid blinking text &c
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Movement may be an unwelcome distraction, so always provide a way of turning off animated effects
•
• Animated GIFs, JavaScript animation: this can usually be done in the browser
Flash: add controls to movie to stop or skip it
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Users with cognitive difficulties can become confused if windows open spontaneously, so don't use pop-ups

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Things have to work
Static HTML errors
• Validate HTML
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 But beware of browser bugs
Client-side script errors
Server-side programming errors
443–445

445–447
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Most important thing about a Web site is its content
Most beautifully designed accessible site will attract no repeat visitors if the content is of no interest to anybody
Compelling content can overcome poor design
Good design practice can make compelling content more readable, navigable, welcoming,…

448–451
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How easy is it for visitors to find information or use services?
Much of the research conducted into usability suffers from poor methodology
• Small and unrepresentative samples relative to population of Web users
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• Emphasis on task-oriented experimentation
Observation of users is valuable but not rigorous science

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Not cast-iron rules
Mostly common sense and courtesy
Treat as check list
• If not followed, know why not
452

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Put the user first
Put the user in control
Don't provide too much choice
Don't make assumptions about users' behavior
Use technology judiciously
Understand your site's context
Keep up with change
Don't neglect aesthetics
Know your limitations
452–456