Transcript Background - Computer Science Department

CSIS-390: Web Application
Development
Important Background about
the field of Web Design
Dr. Breimer
Outline
1. Web Design is a diverse field
2. Standards are important
•
4 reasons
3. Web Design teach critical concepts
•
Separation of content, structure and style.
4. Internet Explorer isn’t the only browser?
•
Browser History
Definition
• Web design is the design of websites and web
applications using HTML, CSS and images.
Definition
• Websites can be very diverse.
E-trade
Facebook


Playhouse Disney
Protein Databank
Web Design Career #1
Visual Designer
• Uses
▫ Adobe PhotoShop,
▫ Fireworks,
▫ Flash, etc.
• Expertise in graphic design, layouts, color
theory, etc.
Web Design Career #2
Interface Designer
• Expertise in
▫ graphical programming,
▫ human computer interaction and
▫ interfaces
• Background in behavioral science, ergonomics,
etc.
Web Design Career #3
Software Developer
• Most modern software has web-based
components.
• Most new applications are entirely web-based.
• Programmers need to know HTML, CSS, etc.
Web Design Career #4
Database Administrator
• Almost all Databases interface with web
technologies.
• Large website are entirely database-driven.
• Database Administrators also need to know
HTML, CSS, XML, etc.
Web Design Career #5
Web Master/Web Authoring
• Larger websites require extensive content
management.
• Developing and managing content is a specialty.
• Writing conventions and styles are different on
the web.
Web Design Career #6
Marketing & Advertising
• Online marketing is an entire field.
• Web technology can help marketers achieve new
innovations.
• Marketers & Advertisers need to know about
fundamental web technologies.
HTML
• HyperText Markup Language
• A simple text document can be “marked-up”
with tags to specify how it should be interpreted.
• <h1>Level 1 Header</h1>
HTML
• HTML was supposed to be a structural or
“semantic” language,
▫ But, the Browser Wars led to the introduction of
“style” or formatting tags.
▫ “style” tags are bad!
▫ They have been removed from the HTML
standards (called deprecation).
CSS
• Cascading Style Sheets
• Used to specify the style/appearance of
structural elements (HTML tags).
• CSS was part of the original design of the web,
• but its use was almost entirely abandoned
between 1996 and 2004.
Why are “style” tags bad?
• The best answer is very complicated
• Short Answer:
▫ It is hard to maintain and even harder to change.
Semantic vs Style
Semantic =
Has Meaning
Style =
Specifies Appearance
Semantic vs Style
Semantic  Meaning
Style   Appearance
<img src=“tiger.jpg”>
<img src=“tiger.jpg”>
<span class=“caption”>
This is a picture of a tiger
</span>
<font type=“Arial”
style=“italic”
size=“10pt”>
This is a picture of a tiger
</font>
A caption is meaningful.
Images typically have a
caption that describes the
image.
Here, we specify how to
display the caption but
not the fact that it’s
actually a caption.
Semantics + CSS is better!
<span class=“caption”>Figure 1</span>
<span class=“caption”>Figure 2</span>
<span class=“caption”>Figure 3</span>
…
<span class=“caption”>Figure 99</span>
.caption {
font-size: 10pt;
font-style: italic;
}
This is why the font tag sucks!
(it’s a style tag)
<font type=“Arial” style=“italic” size=“10pt”> Figure 1 </font>
<font type=“Arial” style=“italic” size=“10pt”> Figure 2 </font>
<font type=“Arial” style=“italic” size=“10pt”> Figure 3 </font>
…
<font type=“Arial” style=“italic” size=“10pt”> Figure 999 </font>
<font type=“Arial” style=“bold” size=“10pt”> Sub-title </font>
Imaging if you wanted to change the font size to 12pt for all
image captions?
Good luck!
History Lesson: The Good Times
• Standardization was very important in the initial
design of HTML (1991-1994)
▫ HTML was meant to only structural/semantic
▫ The presentation of web pages was left up to the
user, via web browser settings.
• Netscape & Microsoft created “evil” tags
(<font> for example) so that web page
designers could control the presentation of their
web pages.
History Lesson: Browser Wars
• Netscape & Microsoft added many proprietary
enhancements to HTML (1994-1999)
▫ Proprietary == Only works for a specific browser
▫ Proprietary == Not Open == Not standard
• Web authors would use HTML tags to control
the visual presentation, but pages would look
completely different on different browsers.
• In 1998, the web development community and
W3C said “Enough is enough”
• www.webstandards.org was formed
W3C – What is it anyway?
• The World Wide Web Consortium (W3C)
▫ international consortium of web developers
▫ sub-organizations, full-time staff, and regular people
• Work together to develop Web standards
• Mission:
▫ To lead the World Wide Web to its full
potential by developing protocols and
guidelines that ensure long-term growth for
the Web.
www.w3.org
Current Web Standards
• Structural Standards
▫ XHTML 1.0 – This is actually HTML 4.01 rewritten
according to XML standards.
▫ XML – set of rules for creating custom markup
languages.
• Presentation Standards
▫ CSS 1 (Since 1996) fully supported by almost all
browsers
▫ CSS 2 current standard, extends CSS1
▫ CSS 3 the future, extends CSS2
Why Standards?
Advantages
1. Accessibility
2. Forward Compatibility
3. Simpler and Faster Development
4. Faster Download & Display
Why Standards?
1.
Accessibility
2.
3.
Forward Compatibility
Simpler and Faster
Development
Faster Download & Display
4.
• Standardized web pages look good on
all browsers.
• And on all different types of devices.
▫ Cell phones
▫ Handheld computers
▫ Screen readers for the visually
impaired
Why Standards?
1.
Accessibility
2.
Forward
Compatibility
3.
Simpler and Faster
Development
Faster Download &
Display
4.
• Future standards are built on top of
current standards
• Thus, Web pages made today will work
in the future
Note:
• Browser Wars created html tags that were not standard
• These tags won’t display properly in many “standard”
browsers.
• Internet Explorer and Firefox still support these tags, but
not for long.
Why Standards?
1.
2.
3.
4.
• Faster: You don’t have to build
separate websites for separate
browsers/devices
Simpler and Faster
• Concurrent Development:
Development
Content and style can be developed
Faster Download & Display
separately by different teams.
Accessibility
Forward Compatibility
Why Standards?
1.
2.
3.
Accessibility
Forward Compatibility
Simpler and Faster
Development
4.
Faster Download &
Display
• Style/Appearance tags are bloated
• Rather than load bloated HTML for
every page, just load one style sheet for
an entire website
• Example:
<center> <b> <font face="Georgia, Times New Roman, Times, serif"
color=“#880000" size="+2">Sub-title</font> </b> </center>
Rendering Engines
• Browsers actually have different rendering
engines for parsing standard and nonstandard HTML code.
• The <!doctype> or <html> tag tells the
browser which engine to use.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en"
lang="en">
Rendering Engines
• Standard, validated HTML code can be rendered
faster.
▫ Rendering engine doesn’t have to handle special
cases and errors
• Most web browsers can display Non-standard
HTML,
▫ but a more complex rendering engine must be
used
▫ More complex mean slower rendering.
Who cares if the rendering engine is a
little slow?
• True, on modern PCs you won’t notice the
difference.
• However, consider that the device rendering the
web page could be a phone with a 133 MHz
processor.
Standards:
Big
Motivation
• Without standards, you
would have to test how
your website looked
on many different browsers.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
Microsoft IE 60%
Mozilla Firefox 23%
Apple Safari 11%
Google Chrome 4%
Netscape < 1%
Opera < 1%
AOL Explorer
Amaya
Camino
Epiphany
Maxthon
Shiira
HotJava
Nintendo DS
PlayStation PWB
Lynx
Voyager
Micro Browser
Omniweb
Standards: Big Motivation
• Not a problem:
98% of the world uses
four browsers.
• But, more and more people are browsing on
different devices
• Consider cell phones, PDA’s, GPS devices, and
even refrigerators…
▫ All use different browser variations.
• W3C wants the web to fully work on any kind of
device.
▫ Even today, many websites won’t display properly on
small devices.
Internet-enable devices
• Portable Media Players
▫ To buy music
• Automobiles
▫ To send info to mechanics
• Refrigerators
▫ To buy more groceries
• What will they think of next?
Validate Validate Validate
• http://validator.w3.org/
• It’s a pain but…
• At least you know that your web page will
display properly on about 400 different browser
variations.
Tim Berners-Lee (TBL)
• Widely recognized as
▫ The inventor of HTML
▫ First implementor of hypertext concept
▫ Implemented first web browser (text based) and
more importantly, first web server (unix daemon).
• Should be a billionaire but then the WWW
wouldn’t be so cool!
• I love the man! You should love him too.
Web Browser History
• 1991: TBL makes the first web browser in his
physics labs. Dr. B gets his braces off and
discovers Clearasil.
• 1993: Mosaic (the first real graphical browser)
is built. Free, open source, works for Mac’s,
Windows, and UNIX. The birth of free porn.
• 1994: Netscape forms, they develop a browser
and immediately start adding proprietary tags.
• 1995: Microsoft wakes up, makes a browser,
and decides they need to monopolize the
browser market
Browser History
• 1996-1999: Browser Wars…different
versions of JavaScript, CSS, and HTML
emerge. While standards go down the toilet…at
least a lot cool sh*t was developed.
• 1998: Netscape screws Microsoft in a big way
by making its code Open Source.
Microsoft fights back by integrating its
browser into the Windows 98 and 2000.
• 2000: Microsoft wins! Netscape gets bought
by AOL. The .com Bust happens!
Dr. B contemplates becoming a pop star but then
decides to be a professor.
Browser History
• 2002: Kelly Clarkson (not Dr. B) wins
American Idol!
• 2003: Some programmers who once worked for
Netscape form the Mozilla Foundation
• 2005: Firefox busts out on the scene. First
browser to make a serious dent in Microsoft’s
monopoly.
• 2006+: Developers start to make web pages the
correct way as TBL envisioned in 1991
Summary
• Originally HTML was meant to be a
structural/semantic language
• The Browser wars lead to the de-standardization
of HTML.
▫ Proprietary style tags were added.
• Standardization and semantic HTML has made
a comeback
▫ Old school web design is back!