Transcript Multimedia Development Methods

CO42002 MT4 Week 2
WWW Architecture, WebDAV,
graphics, bandwidth & web design
practice
This week
• Underlying Principles & Practice
– Web Distributed Authoring and Versioning (WebDAV)
– Managing your content
– Web Architecture
• Bitmap and Vector Graphics
• Bandwidth implications for human-centred web
design
Last week: Free Multimedia
• What will your future careers in multimedia
depend on?
– Your ability to create new media solutions, at a costeffective price profitably?
– Your ability to create digital media components that
generate revenue?
– Your ability to add value in embedding digital media in
ICT solutions?
– Your ability to pick up technical skills
Contentious introduction #2 As a web
developer I will…
• Handle 2 or 3 clients’ websites a month,
– updating them with new material,
– using the latest web design tools
– to create a really distinctive look?
• Spend most of my times doing pitches and sitting in
meetings trying to figure out what the client wants?
• Co-ordinate a group of other people
– graphics designers, programmers, database people,
– to make sure each site makes more money than it costs?
• Have 2-3 hours per client to do prototypes until the client
is happy and/or runs out of money?
Unit 2
Architecture for WWW, WebDAV, Vector
Graphics, Bandwidth & Web Design
1 Fireworks
2 Underlying Principles
& practice
Tutorial
3 Web Graphics
Standards
4 Appropriateness
of Images
5 Web Design
1. Tutorial: Fireworks Overview
• A graphics tool that started with the web,
instead of print
• As with any new tool:
– Look for interface similarities, and monitor
– Use the tutorial files to take you through the
basics
• http://www.macromedia.com/support/fireworks/documentatio
n/fwmx_tutorials/
Possible problems
• Fonts didn’t look exactly the same on my machine –
perhaps using a narrower Arial font?
• Transparency didn’t look quite the same either! But
close!
• Before next week complete the second of the two
tutorials
• If you are interested look at further tutorials
– http://www.macromedia.com/support/fireworks/tutorial_index.htm
l but not required for coursework
– http://www.macromedia.com/desdev/mobile/articles/palmos_tem
plate.html describes using FW for Palm design
Unit 2
Architecture for WWW, WebDAV, Vector
Graphics, Bandwidth & Web Design
1 Fireworks
2 Underlying principles
& practice
Version
Control
WebDAV
Content
Mgmt
&
Hcie2003
casestudy
Web
Architecture
3 Web Graphics
Standards
4 Appropriateness
of Images
5 Web Design
2. File (dis)organisation.
(From personal experience!)
• Work
•
•
C:/public_html/modules/co42002
– Cache for supply to the website
when ready for release
C:/teaching/modules/co42002
– Development area, then
passed to
•
H:/teaching/modules/co42002
– For system backup and
access from home
• Website:
•
H:/public_html/modules/co42002
– What you, the customer, sees
• Home
•
C:/teaching/modules/co42002
– Because there are never
enough hours in the
working day
Laptop
Lecture Theatre
And WebCT
Version Control
• When things get difficult, poor version control leads to
loss of work –
• We desire X+A+B but we get X+A only (X= original work,
A= A’s changes, B= B’s changes).
X
Developer A
X+A
Master X+A
X
X+B
Copy
All of Developer
B’s work has been
destroyed!!
Developer B X+B
X
WebDAV
• We therefore needed sophisticated tools for larger
development teams
• WebDAV http://www.webdav.org/
– An ongoing project to build this kind of sophisticated
functionality.
– Adds "Distributed Authoring and Versioning" into the WWW
• In Dreamweaver MX onwards
– “WebDAV in Dreamweaver 8 now supports digest authentication and
SSL for secure file transfer and offers improved connectivity with a
wider array of servers.”
WebDAV (cont)
• Needs to be installed on server
• Dreamweaver MX allows you to specify what tools your server
supports:
– a WebDAV-compliant solution
– or a proprietary solution like Microsoft SourceSafe
• Therefore WebDAV is only part of an overall solution
– Requires tools, standards, processes and user trust and procedural
compliance
– Have you ever trusted Microsoft Briefcase?
– Have you ever lost a file and had inadequate backups, or overwritten a
newer version?
Version Control: subset of
Configuration Management
• Software Configuration Management (SCM) is a bigger discipline
covering why changes need to be made – Change Control (CC),
as opposed to what version has which changes (Version Control VC)
• “(Web) Content Management” (WCM) can be seen as part of the
SCM solution, but more to do with delivering the correct content for
a user’s needs – matching profiles
• SCM can be seen as convergence of VC, CC, WCM
• IEEE standards, BCS Specialist Group
• Web Content Management (aka Enterprise Content Management) is
big business - $10b pa
Who can afford WCM?
• All Fortune Global 500 companies turn over $13b, so $10m on a
WCM solution is <0.1% of turnover!
–
The following is an edited quotation from the Fortune Global500 2005 table which describes the
ranking (by turnover) of companies and their profits – both expressed in $m. See
http://money.cnn.com/magazines/fortune/global500/2006/full_list/ for current list
53
Vodafone
62,971.4
-13,910.4
54
Tesco
62,458.7
2,511.3
55
Munich Re Group
60,705.5
2,279.8
56
Nippon Life Insurance
60,520.8
1,886.3
57
Fiat
59,972.9
-1,972.6
58
Royal Bank of Scotland
59,750.0
8,267.4
Audience
Participation:
Where’s Microsoft
in this table?
HCIE2003 Case Study: instant website for picky users
• A site to be created with
– zero resources,
– short timescale
• www.hcie2003.org
– (now http://www.bcs-hci.org.uk/hcie2003/ImportantDates.htm )
– website for a 60-person academic conference
• Unfortunately the audience are
– the UK’s HCI lecturers and usability experts
– No time for design documentation, consultations with client etc
• Decided to use the new version of Dreamweaver and
exploit templates, CSS etc
Lifecycle
• A 2-page Word document and a programme in Excel
– Save as HTML
– “Clean up Word HTML” command (but in DW3 this had a
number of bugs)
– Chop into manageable amounts for each page
• Begin to plan the links
• Begin to create a template
– Try to avoid individually styling words and paragraphs, use CSS
instead
• Update pages and structure in line with “comments”
• Then afterwards, keep it linked to ongoing initiatives
Initial scoping – reusable prototype
• Accessibility: minimal use
of graphics and use ALT
text properly
• <img src=“…” alt="6th
HCI Educators
Workshop: Effective
Teaching and Training in
HCI banner with British
HCI Group logo”>
• Initially menu of six links
from main page, plus text
links
Final front page
• Finally, 8 links in
menu
• All other pages use
the DW template
• Problems?
– Main page still
doesn’t use template
and so is out of date!
– Redefined <body> to
use Arial, but forgot to
do it in template!
Configuration Management
• Keep a list of bugs and requests along with
dates of notification and resolving
• Find the document that is the master data and
get used to uploading changes from there
– Numerous versions of the timetable prepared in Excel
– Wait until timetable is reasonably finalised, before you
spend time making the table look “pretty”
• What follows took about an hour:
• But what happens if
– “the morning structure is changed to have an extra
session”
– “the long session to be split into two shorter sessions”
Conclusions in 2003
• Dreamweaver MX is a jolt when you are used to version
2/3, less so from version 4
• The right hand side of the screen has a lot of detailed
things and access speed will come with practice
• You can create a reasonably structured site (if you really
have to) without documentation but it might be a bit
easier with!
• What similar conclusions will you reach when you use
MX2004, Studio8, Studio9 etc
Assessment
• Coursework requires 25-30 hours, asked you in week 1
to “block out the time in weeks 4-7”.
• Next week you will find out the exact requirements
• Produce a web-site to demonstrate your authoring
capabilities and to explain/educate about 3D technology
standards for the web
– Very short demonstrations – should take 2 minutes to view the
site
– You are trying to “fire the imagination” of users
– Pragmatic, tight documentation
• Due on Thursday 29th March, but plan to finish Fri 23rd!
Quick break
• Clear your minds!
• Come back soon
So what is Web Architecture?
• A set of fundamental principles that influence all W3
activity
• Not the same as
– Information Architecture
– Computer Systems Architecture
• www.w3.org/TR/webarch/summary.html
– There are a lot of principles, constraints and practice issues on
the next five slides
– Highlighted a few for discussion
WebArch Summary 1 of 5
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Principle 2 Global Identifiers. Global naming leads to global network effects.
practice, 2.1 Identify with URIs. To benefit from and increase the value of
the World Wide Web, agents should provide URIs as identifiers for
resources.
constraint, 2.2 URIs Identify a Single Resource. Assign distinct URIs to
distinct resources.
practice, 2.3.1 Avoiding URI aliases. A URI owner SHOULD NOT associate
arbitrarily different URIs with the same resource.
practice, 2.3.1 Consistent URI usage. An agent that receives a URI
SHOULD refer to the associated resource using the same URI, characterby-character.
practice, 2.4 Reuse URI schemes. A specification SHOULD reuse an
existing URI scheme (rather than create a new one) when it provides the
desired properties of identifiers and their relation to resources.
WebArch Summary 2 of 5
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practice, 2.5 URI opacity. Agents making use of URIs SHOULD NOT
attempt to infer properties of the referenced resource.
practice, 3.2 Reuse representation formats. New protocols created for the
Web SHOULD transmit representations as octet streams typed by Internet
media types.
constraint, 3.3 Data-metadata inconsistency. Agents MUST NOT ignore
message metadata without the consent of the user.
practice, 3.3 Metadata association. Server managers SHOULD allow
representation creators to control the metadata associated with their
representations.
principle, 3.4 Safe retrieval. Agents do not incur obligations by retrieving a
representation.
practice, 3.5 Available representation. A URI owner SHOULD provide
representations of the resource it identifies.
principle, 3.5 Reference does not imply dereference. An application
developer or specification author SHOULD NOT require networked retrieval
of representations each time they are referenced.
WebArch Summary 3 of 5
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practice, 3.5.1 Consistent representation. A URI owner SHOULD provide
representations of the identified resource consistently and predictably.
practice, 4.2.1 Version information. A data format specification SHOULD
provide for version information.
practice, 4.2.2 Namespace policy. An XML format specification SHOULD
include information about change policies for XML namespaces.
practice, 4.2.3 Extensibility mechanisms. A specification SHOULD provide
mechanisms that allow any party to create extensions.
practice, 4.2.3 Extensibility conformance. Extensibility MUST NOT interfere
with conformance to the original specification.
practice, 4.2.3 Unknown extensions. A specification SHOULD specify agent
behavior in the face of unrecognized extensions.
practice, 4.3 Separation of content, presentation, interaction. A specification
SHOULD allow authors to separate content from both presentation and
interaction concerns.
WebArch Summary 4 of 5
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practice, 4.4 Link identification. A specification SHOULD provide ways to
identify links to other resources, including to secondary resources (via
fragment identifiers).
practice, 4.4 Web linking. A specification SHOULD allow Web-wide linking,
not just internal document linking.
practice, 4.4 Generic URIs. A specification SHOULD allow content authors
to use URIs without constraining them to a limited set of URI schemes.
practice, 4.4 Hypertext links. A data format SHOULD incorporate hypertext
links if hypertext is the expected user interface paradigm.
practice, 4.5.3 Namespace adoption. A specification that establishes an
XML vocabulary SHOULD place all element names and global attribute
names in a namespace.
practice, 4.5.4 Namespace documents. The owner of an XML namespace
name SHOULD make available material intended for people to read and
material optimized for software agents in order to meet the needs of those
who will use the namespace vocabulary.
WebArch Summary 5 of 5
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constraint, 4.5.5 QNames Indistinguishable from URIs. Do not allow both
QNames and URIs in attribute values or element content where they are
indistinguishable.
practice, 4.5.5 QName Mapping. A specification in which QNames serve as
resource identifiers MUST provide a mapping to URIs.
practice, 4.5.7 XML and "text/*“. In general, a representation provider
SHOULD NOT assign Internet media types beginning with "text/" to XML
representations.
practice, 4.5.7 XML and character encodings. In general, a representation
provider SHOULD NOT specify the character encoding for XML data in
protocol headers since the data is self-describing.
principle, 5.1 Orthogonality. Orthogonal abstractions benefit from orthogonal
specifications.
principle, 5.3 Error recovery. Agents that recover from error by making a
choice without the user's consent are not acting on the user's behalf.
Unit 2
Architecture for WWW, WebDAV, Vector
Graphics, Bandwidth & Web Design
1 Fireworks
2 Underlying principles
& practice
Tutorial
3 Web Graphics
Standards
SVG
GIF
JPEG
Methodology
PNG
4 Appropriateness
of Images
Profile Users
Platforms
5 Web Design
Basic Mistakes
Information
Architecture
3. Web Graphics Standards
• Poole & Bradley Chapter 3
– Parsing: Why differentiate between animated and still
graphics – all web graphics are delivered over time
and the user sees the screen change?
• England & Finney Chapter 8
– A more traditional and detailed examination of
graphics themselves, their production. (Much you will
have tackled in level 3)
Web graphics - the basics: GIF
• GIF – a patented format (due to LZW) US patent
4,558,302
– www.unisys.com/about__unisys/lzw
– Basic patent due to expire 1994, but
www.gnu.org/philosophy/gif.html cites patents until 2006
– “For each registered copy of a program that uses the LZW compression
technology, the developer is to pay 1.5% of the sale price of the
program to CompuServe, or $0.15, whichever is greater”
(http://lpf.ai.mit.edu/Patents/Gif/Gif.html )
• What’s the big fuss? Photoshop Elements should now be
$1 cheaper!
JPEG
• Lossy (though that can be scaled)
• 24 bit colour – great for photos
• Progressive file loading – an animation effect (bit like
interlaced GIF)
• But no transparency – need to use tricks with
backgrounds
• But patent problems re-emerge – who’s accurate?
– http://swpat.ffii.org/patents/effects/jpeg/index.en.html
– http://www.boingboing.net/2006/05/30/jpeg_patent_invalida.html
– http://en.wikipedia.org/wiki/JPEG#Potential_patent_issues
PNG
• Patent–free alternative to GIF
• Advantages:
– Supports 24 bit colour
– Lossless compression
– Can contain transparency or an alpha channel
gradients
– Can be progressive (interlaced for low-resolution
loading)
• Disadvantages
– Not yet supported by all browsers
– Can be large
SVG – Scalable Vector Graphics
• Now a reality in commercial products
– Supplies much-needed functionality
– …and XML
• For animated as well as still images
• Can be consumed regardless of vision. Some
advantages suggested at
– wwws.sun.com/software/xml/developers/svg/
– www.adobe.com/svg/
• SVG parsing in Flash explained at
– www.macromedia.com/devnet/flash/articles/parse_svg.html
Unit 2
Architecture for WWW, WebDAV, Vector
Graphics, Bandwidth & Web Design
1 Fireworks
2 2 Underlying principles
& practice
3 Web Graphics
Standards
Fake Logo
Transparency
Scalability
4 Appropriateness
of Images
Placeholders/
Image Maps
5 Web Design
4. Appropriate Images: quality and
time
• What do we mean by appropriate?
– Culturally acceptable?
– A moving target (fashion, technical advances)
– Scalable output
• Quality v bandwidth trade-off
• Download delays remain damaging
– How long would you wait?
– Does this change if you are:
• At home, work, university?
• On a mobile phone at 15p per minute?
•
Limited colour ranges
– B&W or 16-grey – PDA, mobile phone
– 256 or 4096 colours – next generation PDA/phone
– Web-safe palettes (216)
•
Restricted palette can be damaging to brand identity
– see FakeLogo for an example
Transparency
•
•
•
•
•
Annoying stray pixels around the edge of the logo
Caused by anti-aliasing against background colour
Can make the work look shoddy, amateurish.
You can waste hours painting out each pixel
Either require a consistent background colour as part of
brand identity, and anti-alias against this
• Or use rectangular logos!
Placeholders
• A 2-colour outline “Low Src” graphic will ensure that
when the image loads, the screen doesn’t change size.
– Width and height can also be set in the <IMG> tag
– <IMG SRC=“file” width=“xx” height=“yy” LOWSRC=“low-res
file”>
– Set these in Dreamweaver’s properties
• The transition, from low-res to final graphic, is also
effectively part of your screen’s “animation”
Unit 2
Architecture for WWW, WebDAV, Vector
Graphics, Bandwidth & Web Design
1 Fireworks
2 2 Underlying principles
& practice
3 Web Graphics
Standards
4 Appropriateness
of Images
Methodology
Profile Users
Platforms
5 Web Design
Design Guidelines
Information
Architecture
Web Design Considerations
• Need some sort of structured framework – eg
PACT, Scenarios, ISO 13407
• Fundamental dichotomy: “match content to the
users” or “design for universal access”?
• Avoid the basic mistakes
– Basic accessibility requirements defined in
http://webxact.watchfire.com/ (formerly “Bobby”)
– Poorly titled, or untitled pages
– Pages that give no indication if they are current
Project Specification
• Target User
– Not just “people like you”…or your manager or the
client
• Profile Assumptions - are you already limiting
access to the site?
Race
Language
Culture
Religion
Impairment Reading Age
• Can you think of any others?
Connection Speed
Plug-ins
Screen-size
Examples of hardware/platform
constraints
• PC
–
–
–
–
Mac
PDA
TV
Unix
• OS
– W9x, NT, XP
– Others
• Hardware
– Soundcard
– Midi
– Colour Resolution
• Screen size
–
–
–
–
1024 x 768
800 x 600
640 x 480 ...
160 x 120
Project Specification
• Connection Speed
–
–
–
–
–
–
–
–
GSM Mobile: 9.6-14.4 kbs
GPRS (up to) 53.6 kbs
EDGE 200kbs+
3G 384kbs
Modem 33-56kbs - typically 4-5kB/s
Cable Modem/DSL 0.5-10mbs(but can be capped and choked)
Satellite Feed ?kbs
Network T1, T3, SuperJanet
• But remember the speed will be that of the weakest link
in the chain!!
Web Usage Statistics – Sources
(but use with caution)
http://www.w3schools.com/browsers/browsers_stat
s.asp
http://www.macromedia.com/shockwave/download
/activex/flash/ieWin32400.htm
http://www.websiteoptimization.com/bw/
http://www.upsdell.com/BrowserNews/stat_trends.
htm
http://www.thecounter.com/stats/
Bandwidth
• On a good day you might just get these speeds for each
element you download
Content
Size
28.8kbps
128kbps
1.5Mbps
Basic graphics
or Flash
30kB
10-12s
2-3s
1s
Detailed Flash
Movie
100200kB
1-2m
10-30s
1-2s
MP3 or video file
(per minute)
1mB
8-10m
1-3m
8-10s
Bandwidth
• Remember that users have to
– Start plug-ins - eg Java
– Swap applications to/from hard disk
• And may have to download … or not even be
allowed to install …
– ActiveX files
– Xtras, fonts etc
– New versions of plug-ins
Bandwidth
• Server-end capacity is finite as well (and often charged
e.g. trigger more than 100MB a month and your ISP
charges you more!
• Routers and links have finite throughput as well
• Push v Pull technology
– Push still at early stages
– Internet Radio appliances appearing
• To speed up downloads, and to avoid out of date
images, don’t duplicate graphics files in each folder have each only once on a site
Design Guidelines
• Define and locate content
– assume growth
– locate external links cautiously
• Page Titles - create them at the time
• “Last-changed on” dates - a rod for your own
back, or a vital affirmation to the reader?
• Allow, even prompt for, feedback
• In the last twelve months contribution has
become ubiquitous on websites
Design Guidelines
• HTML Compatibility
– does not exist - trust but verify!
• Layout and Flow
– Multimedia always requires management of the user’s
“temporal experience”
• Backgrounds & other colour combinations
– Vision issues – “colour-blindness”
• http://www.bbc.co.uk/education/betsie/inverse/tech.html
– Does content still stand out?
Design Guidelines
• Text
– Think “advertising”, not “literature”
– “Big enough” font but avoid scrolling
– Break conventions at your peril
• Graphics
– ALT text for every image (or ALT=“” for shims)
• See debate at http://www.cs.tut.fi/~jkorpela/html/alt.html#empty
– “Less is More”
– Image-maps only work with those who can read maps
(or interpret the semiotics)!
Design Guidelines
• CSS – change the styles only in one location for
the whole site
• Frames
– Present usability & accessibility problems and have
been replaced by <DIV> layers
– At least keep duplicate site for the frame-less
• Test scripts – what do you test and when?
• Check what print-outs will look like – in fact,
ensure that users can print out (ie don’t
suppress menu-bar)
• Maintenance schedule for the site
Scenario
• A Computing IT agency wants to develop a website, and use this to corner the market in fresh
graduates with up to date skills in demand by
industry
– Who are the users?
– How would you research them?
– What techniques would you use?
Navigation & Information
Architecture
• Basic Issues (think of real-life)
–
–
–
–
–
–
–
What can I do here?
Where am I?
Where was I?
How did I get here?
Where can I go?
How do I get out of here?
Will I be able to get back here if I change my mind?
• More advanced: How do I accomplish what I want to?
Navigation & Information
Architecture
• Information Structure
– Dewey Decimal
– Book/Record Shops - alphabetic/category
•
•
•
•
How do you organise your books/CDs?
Linked items in the mind of the owner
Can we design for serendipity?
Familiarity breeds contempt? Or Jakob’s law “most
people spend most time on other sites”
References
• England, E & Finney, A (2002) Managing Multimedia Book 2
Technical Issues, Addison Wesley 0-201-72899-0
• Poole, C & Bradley, J (2003) Developer’s Digital Media
Reference: New Tools, New Methods, Focal Press 0-240-80501-1
• Lazar, J. (2001) User-centred Web Development, Jones & Bartlett
• Tay Vaughan pp 384-7 496-505
• www.WebPagesThatSuck.com
• .Net Magazine
Tutorial
Unit 2
Architecture for WWW, WebDAV, Vector
Graphics, Bandwidth & Web Design
1 Fireworks
2 2 Underlying principles
& practice
Version
Control
WebDAV
Content
Mgmt &
Hcie2003
Casestudy
Web
Architecture
GIF
3 Web Graphics
Standards
Transparency
Scalability
SVG
JPEG
Methodology
Fake Logo
PNG
4 Appropriateness
of Images
Profile Users
Platforms
Placeholders/
Image Maps
5 Web Design
Design Guidelines
Information
Architecture
Summary - Now You Understand...
 Some underlying principles about how the web is and will be
 A bit about graphics!
 Bandwidth & baseline platform / browser limitations on web design
 Basic user-centred web design guidelines (& limitations)
 Basics of web design
 And so will be able to develop appropriate site and information
architectures, and create a better web-site