Download IMY 110 Theme 15 W3C – The World Wide Web Consortium

IMY 110
Theme 15
W3C – The World Wide Web
Consortium
1. World Wide Web
Consortium
1.1. Introduction
In the late 1980's Tim Berners Lee worked on a new system called the
World Wide Web at CERN Laboratories. This system quickly took the
world by storm and became one of the largest information distribution
and communication systems in the world. Please read through theme
1 again to familiarise yourself with this history. A core language used
to make the World Wide Web so easy to use was HTML, and in the
early 1990's we saw a boom of browsers developed by different
software vendors that could read HTML. Each vendor tried to gain an
advantage over their competition by implementing functionality that
would distinguish their browser over others. Very quickly every
browser boasted with its own proprietary tags. Even today Internet
Explorer allows one to style scrollbars, where other browsers like
Mozilla Firefox does not support that functionality.
The original purpose of the World Wide Web and HTML is to allow
people to share information in a platform independent way. Allowing
different browsers to specify different “flavours” of HTML defeated this
purpose.
When Tim Berners Lee left CERN in 1994, he joined forces with
DARPA(The US Military) and MIT(Massachusetts Institute for
Technology) to start the World Wide Web Consortium (or W3C).
Its aim is to regulate World Wide Web standards and protocols and so
ensure compatibility and agreement among all concerned parties. By
prescribing an independently recognised standard and various
recommendations, the W3C tries to avoid incompatibility between
different vendors, as well as potential conflicts through bad coding
use. It also ensures a certain level of backwards-compatibility. Since
web technology changes so fast, it is possible that users are still using
older browsers, or even accessing older web pages with newer
browsers. The W3C attempts to manage this compatibility.
1.2. Aims of the W3C
The main aim of the W3C is to develop common protocols that
promote the web's evolution and ensure its interoperability. By
promoting interoperability and encouraging an open forum for
discussion, W3C commits to leading the technical evolution of the
Web. The W3C has developed more than fifty technical specifications
for the Web's infrastructure and is already laying the foundations for
the next generation of the Web (Web 2.0). The W3C's technologies
make the Web:
●
●
●
robust
scalable
adaptive infrastructure
The W3C goals for the World Wide Web are:
●
●
●
Universal Access
Semantic Web
Web of Trust
1.3. Universal Access
To make the Web accessible to all by promoting technologies that
take into account the vast differences in:
● culture
● languages
● education
● ability
● material resources
● access devices
● physical limitations of users on all continents
1.4. Semantic Web
The aim of a Semantic Web is to develop a software environment that
permits each user to make the best use of the resources available on
the Web. The web now “understands” the user, and adapts to a user's
needs. This is a personalised web.
1.5. Web of Trust
Current trends in web development lets us view the web as a tool or
function, rather than just a source of information. We are doing online
shopping and online banking. Suddenly the need for a secure web
and authentication is crucial.
The aim of the W3C is to guide the Web's development with careful
consideration for the novel legal, commercial, and social issues raised
by this technology.
2. The Need for Standards
The World Wide Web Consortium (W3C), along with other groups
and standards bodies, has established technologies for creating
and interpreting web-based content.
These technologies, which we call web standards, are carefully
designed to deliver the greatest benefits to the greatest number of
web users while ensuring the long-term viability of any document
published on the Web.
Designing and building with these standards simplifies and lowers
the cost of production, while delivering sites that are accessible to
more people and more types of Internet devices.
Sites developed along these lines will continue to function correctly
as traditional desktop browsers evolve, and as new Internet
devices come to market.
3. W3C DTD's
DTD is short for “Document Type Definition” and it is a file on the
web that describes a valid structure for that kind of document. Your
websites MUST adhere to a DTD. The DTD specification comes at
the head of each HTML page.
e.g.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0
Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1transitional.dtd">
<html>
<head>
<title>
University Homepage
</title>
</head>
<body>
...content...
</body>
</html>
3.1. HTML DTD's
There are four types of HTML DTD's:
○
Strict
This is the most stringent DTD and allows only the newest tags and
rules. No depricated tags or sloppy code is allowed. We want to
ultimately design websites that adhere to these standards.
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
○
Transitional
Since most browsers are more lenient and still allows for the use of
some depricated tags, most websites adhere to the transitional DTD.
Adhering to this DTD ensures you that your website will display fine
on most general browsers, but it does not guarantee that new
standards will support this website. If you design websites that will
need to stay up for about 5 years or longer, consider switching to
strict.
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01
Transitional//EN" “http://www.w3.org/TR/1999/REChtml401-19991224/loose.dtd”>
○
Frameset
Use this DTD if you ever use frames.
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Frameset//
EN" “http://www.w3.org/TR/1999/REChtml401-19991224/frameset.dtd”>
3.2. XHTML DTD's
There are three types of XHTML DTD's:
○
Strict
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
○
Transitional
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0
Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1transitional.dtd">
○
Frameset
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0
Frameset//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1frameset.dtd">
4. Why is valid HTML so
important?
Browser display problems: Even the simplest errors can cause big
problems - particularly in browsers like Netscape and Opera. They
adhere more stringently to W3C standards. Although Explorer may
ignore a problem like a missing closing TABLE tag, Netscape
ignores the entire table and all its contents.
Accessibility problems: Screen readers (an assistive technology
used by many people with vision problems) are basically simple text
browsers. They often have problems with HTML code errors particularly missing attributes.
Incorrect search engine indexing: Search engine spiders are also
basic text browsers. While an advanced browser like Explorer 6 or
Netscape 7 may not care if you forget to close some quotation marks
inside a tag, a search engine spider does!
Coding errors hide information from search engines, even though it
displays fine in a browser.
5. Why do people have bad
code?
○
○
○
○
HTML editors don't conform to W3C standards.
Incorrect information in books.
Outdated web sources
Microsoft Word "save as Web page" function.
6. How do I validate my
code?
○
○
http://validator.w3.org/
http://www.netmechanic.com/products/maintain.shtml