Web Development Techniques

HTML 2.0 (RFC 1866) was developed by the IETF's HTML Working Group, which closed in 1996 it set the standard for core HTML features based upon current practice in 1994. Note that with the release of RFC 2854, RFC 1866 has been obsolate and its current status is HISTORIC.

HTML 3.2 W3C's first Recommendation for HTML which represented the consensus on HTML features for 1996. HTML 3.2 added widely-deployed features such as tables, applets, text-flow around images, superscripts an subscripts, while providing backwards compatibility with the existing HTML 2.0 Standard.

HTML 4.0 First released as a W3C Recommendation on 18 December 1997. A second release was issued on 24 April 1998 with changes limited to editorial corrections. This specification has now been superseded by HTML 4.01.

The Most Important Differences:

XHTML elements must be properly nested
XHTML documents must be well-formed
Tag names must be in lowercase
All XHTML elements must be closed

Elements Must Be Properly Nested

In HTML some elements can be improperly nested within each other like this:

 This text is bold and italic 

In XHTML all elements must be properly nested within each other like this:

 This test is bold and italic 

Note: A common mistake in nested list, is to forget that the inside list mustbe within an element.

Documents Must Be Well-formed

All XHTML elements must be nested within the <html> root element. All other elements can have sub (children) elements. Sub elements must be in pairs and correctly nested within their parent element.

Tag Names Must Be In Lower Case

This is because XHTML documents are XML applications. XML is case-sensitive. Tags like and are interpreted as different tags.

This is wrong:

<BODY>

 This is a paragraph 

</BODY>

<html>

<head> ... </head>

<body> ... </body>

</html>

This is correct:

<body>

 This is a paragraph 

</body>

All XHTML Elements Must Be Closed

Non-empty elements must have an end tags.

This is Wrong:

 This is paragraph

 This is another paragraph

This is correct:

 This is a paragraph 

 This is another paragraph 

Empty Elements Must Also Be Closed

Empty elements must either have an end tag or the start tag must end with />

This is Wrong:

This is break 

Here comes a horizontal rule <hr>

Here's an image <img src="happy.gif" alt="Happy face">

This is Correct:

This is a break 

here comes a horizontal rule: <hr />

Here's an image <img src="happy.gif" alt="Happy face"/>

Mandatory XHTML Elements

All XHTML documents must have a DOCTYPE declaration. The html, head and body elements must be present, and the title must be present inside the head element.

This Is a Minimun XHTML document template:

<!DOCTYPE doctype goes here >

<html xmlns="http://www.w3.org/1999/xhtml">

<head>

<title> Title goes here </title>

</head>

<body>

Body text goes here

</body>

</html>

Note: The DOCTYPE declaration is not a part of the XHTML document itself. It is not an XHTML elements and it should not have a closing tag.

Note: The xmins attribute inside the <html> tag is required in XHTML. However, the validator on w3.org does not complain when this attribute is missing in an XHTML document. This is because "xmins=http://www.w3.org/1999/xhtml" is a fixed value and will be added to the <html> tag even if you do not include it.

3.3. ASCII Entities with new Entity Names

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3.4. ISO 8859-1 Symbol Entities

3.2. HTML and ASCII

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HTML uses standard 7-BIT ASCII when transmitting data over the Web. 7-BIT ASCII represents 128 different character values (0-127)

Hexadecimal values can be used to display non-standard letters and characters in browsers and plug-ins. HTML 4.01 supports the ISO 8859-1 (Latin-1) character set.

The lower part of ISO-8859-1 (codes from 0-127) is the original 7BIT ASCII standard. Most of these characters can be used without a character reference.

The higher part of ISO-8859-1 (codes from 160-255) can all be used using character entity names. Note that the entity names are case sensitive.

3.1. The anatomy of an HTML Document

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HTML is the lingua france for publishing hypertext on the World Wide Web. It is a non proprietary format based upon SGML, and can be created and processed by a wide range of tools, from simple plain text editors - you type it in from scratch - to sophisticated WYSIWYG authoring tools.

It is the base code for web pages.
It creates a visual presentation that is displayed by a web browser.

The commands in HTML coding (known as Tags) are enclosed in angel brackets < >. THe tags normally come as a set. One to open a command, and one to close it. Everything between the two tags will be affected by them. The closing tag uses a forward slash ( / ) in it.

< TAG NAME > </TAG NAME >

Tags are made up of elements, properties, and values. The command letters or words are called elements. Some ellements have declared settings called properties. These properties help describe or shape the way the element will work of function. The property settings are known as values. Some tags can have many properties, others have none.

<html>

<head>

<title> Welcome page </title>

</head>

<body>

Welcome to My Web Page

</body>

</html>

HEAD An introduction to the web page. In this area, some of the settings for the web page are introduced such as the TITLE, and information for search engines.

TITLE The title for the web page. This name will appear in the title bar at the top of the browser window. It is also used as the file name if someone 'bookmarks' your page or saves it. Typically, the TITLE should be a descriptive statement up to 200 characters.

BODY Main program section for web page. This is where it all happenes.

<html> tag - Language Attributes

2.2. Common Browser Technologies

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Internet Explorer

Internet Explorer (IE) by Microsoft is the most common Internet browser today. IE was Introduced in 1995 and passed Netscape in popularity in 1998.

Netscape

Netscape was the first commercial Internet browser. It was introduces in 1994. Netscape gradually Lost its popularity to Internet Explorer.

Mozilla

The Mozilla Project has grown from the ashes of Netscape. Browsers based on Mozilla code is the second largest browser family on the Internet today. represending about 30% of the Internet community.

Firefox

Firefox is a new browser from Mozilla. It was released in 2004 and has grown to be the second popular browser on the Internet.

Opera

Opera is another Internet browser. It is known to be fast and small, standards-compliant, and available for many operating systems. Opera is the Preferred browser for a number of small devices like mobile phones and hand-held computers.

2.2.1. Uniform Resource Identifier (URI)

A Unform Resource Identifier (URI), is a compact string of characters used to Identify or name a resource. the main purpose of this identification is to enable interaction with representations of the resource over a network, typically the World Wide Web, using specific protocols. URIs are defined in schemes defining a specific ayntax and associated protocols.

The URI syntax is essentially a URI scheme name like "HTTP" , "FTP" , "mailto" , "URN" . "tel" , "rtsp" , etc, followed by a colon character, and then a scheme-specifuc part. The syntax and semantics of the scheme-specific part are deremined by the specifications that govern the schemes, although the URI syntax does force all schemes to adhere to a certain generic syntax that, among other things, reserves certain characters for special purposes, without always saying what those purposes are. The URI syntax also enforces restrictions on the scheme-specific part, in order to, for example, provide for a degree of consistency when the part has hierarchical sructure.

URIs and URLs have a shared history. The idea of a URL - a short string representing a resource that is the target of hyperlink - was implicitly introduced in early 1990 in Tim Berners-Lee's proposals for HyperText. At the time, it was called a hypertext name or document name.

Examples of absolute URIs

http://somehost/absolute/URI/with/absolute/path/to/resource.txt
ftp://somehost/resource.txt

Examples of URI references

http://example/resource.txt#frag01
http://somehost/absolute/URI/with/absolute/path/to/resource.txt
/relative/URI/with/absolute.path/to/resource.txt
relative/path/to/resource.txt
../../../resource.txt
resource.txt
/resource.txt#frag01
#frag01

2.1 The Idea of hypertext and hypermedia

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HTML was devised as an easy means to format textual documents. HTTP is the method for delivering HTML documents. which the client browser then renders into an on-screen image.

HTML and HTTP were both invented bt Tim Berners-Lee, who was then working as a computer and networking specialist at a swiss research institute by the name of CERN. He wanted to give the Institute's researchers a simple markup language that would enable them to share their research papers via the internet. Berners-Lee based HTML onSGML, an international standard for marking uptext for presentation on a variety of physical devices. The basic idea of SGML is that the document's structure should be separated from its presentation.

To date, HTML has gone through four major standards, including the latest which is 4.01. In addition to HTML, Cascading Style Sheets (CSS) and Extensible Markup language (XML) have also provided a valuable contribution to the way of the web.

XHTML 1.0 is the latest standard for web doucuments. This standard infuses the HTML 4.01 standard with extensible language constructs courtesy of XML.

1.3. Addressing and naming on the Internet

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Internet Protocol Addressing

Each mchine connected to an IP network (such as the Internet) is addressed using a unique 32 bit number, the IP address.

Many machines will have more than one IP address - for example a machine running virtual websites will have an IP address for each website they host.

Other times a pool of IP addresses is shared between a number of machines - eg on a dynamic-IP dialup connection your machine will be allocated a different IP address each time you connect.

These addresses are usualy written in DOtted Quad notation (IPv4), as a series of four 8bit numbers, wrtten in decimal and separated by periods. For example 151.196.75.10.

Each number is in the range 0 to 255 - so if you ever see something that looks like an IP address with numbers outside those ranges it's not a real address.

Domain Name System

On the Internet, the Domain Name System (Dns) associates various sort of information with so-called domain names; most importanly, it serves as the "phone book" for the Internet; it translates human-readable computer hosatnames, into the IP addresses that networking wquipment needs for delivering information. it also stores other information such as the list of mail exchange servers that accept email for a given domain. In providing a worldwide keyword-based redirection service, the Domain Name System is an essential component of contemporary Internet use.

Parts of a domain name

A domain name usualy consists of two or more parts (technically labelss), separates by dots. for example Google.com

The rightmost label conveys the top-level domain
Each label to the left specifies a subdivision or subdomain of the domain above it Note that "subdomain" expresses relative dependence, not absolute dependence for example google.com. comprises a subdomain of the Com domain.
A hostname refer to a domain name that has one or more associated IP addresses.

1.2. The Architecture of the Internet

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The internet is by definition a meta-network, a constantly changin collection of thousand og individual networks intercommunicating with a common protocol.

The Internet architeccture is described in its name, a short form of the compound word "Inter-networking". This architecture is based in the very specification of the standard TCP/IP protocol, designed to connect any two networks which may be very different in internal hardware, software and technical design. Once two networks are interconnected, communication with TCP/IP is enabled end-to-end, so that any node on the Internet has the near magical ability to communicate with any other no matter where they are. This openness of design has enabled the Internet architecture to grow to a global scale.

In practice, the internet technical architecture looks a bit like a multi-dimensional river system, with small tributaries feeding medium-sized streams feeding large rivers. For example, an individual's access to the internet as often from home over a modem to a local internet service provider who connects to a regional network connected to a national network. At the office, a desktop computer might be connected to a local area network with a company connection to a corporate internet connected to several national Internet service providers. In genaral small local Internet service providers connect to medium-sized regional networks which connect to a large national networks, which then connect to a very large bandwidth networks on the Internet backbone. MOst Internet service providers have several redundant network cross-connections to other providers in order to ensure continuous availability.

1.1. Background & History

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The Internet has revolutionized the computer and communications waorld like nothing before. The invention of the telegraph, telephone,radio and computer set the stage for this unprecedented integration of capabilities. The Internet is at once a world-wide brodcasting capability, a mechanism for information dissemination, and a medium for collaboration and interaction between individuals and their computers without regard for geographic location.

There is the technological evolution that began with early research on packet switching and the ARPANET (and related technologies), and whre current research continues to expand the horizons of the infrastructure along several dimensions, such as scale, performance, and higher level functionality.

1.1.1. Internet history in brief

1876-Telephone. Alexander Graham Bell Exhibits.

Telephones exchanges provide the backbone of Internet connections today.
Modems provide Digital to audio conversion to allow computers to connect over the telephone network.

1957 - USSR Launches Sputnik, first artificial earth satellite.

The start global telecommunications, Satellites play an important role in transmitting all sorts of data today.
In response, US forms the Advanced research Projects Agency (ARPA) within the Department Of Defense (DoD) to establish US lead in science and technology applicable to the military.

1962 - 1968 Packet switching (PS) networks developed.

As we will see later the Internet relies on packets to transfer data.
The origin is military : for ulmost security in transferring information of networks (no single outage point).
Data is split into tiny packets that may take different routes to a destination.
More than one route available - if one route goes down another may be followed.
Networks can withstand large scale destruction (Nuclear attack - This was the time of the Cold War).

1969 - Birth of Internet.

ARPANET commissioned by DoD for research into networking.
First node at UCLA (Los Angeles) closely followed by nodes at Stanford Researh Institute, UCSB (Santa Barbara) and U of Utah (4 Nodes).

1971 - People communication over a network.

15 nodes (23 hosts) on ARPANET.
E-mail invented - a program to send messages across a distributed network E-maol is still the main way of inter-person communication on the Internet today.

1972 - Computers can connect more freely and easily.

First public demonstration of ARPANET between 40 machines.
Internet working Group (INWG) crated to address need for establishing agreed upon protocols.
Telnet specification . Telnet is still a relevant means of inter-machine connection today.

1973 - Global Networking becomes a reality

First international connections ti the ARPANET : University College of London (England) and Royal Radar Establishment (Norway).
Ethernet outlined - this how local networks are basically connected today.
Internet ideas started.
Gateways define how large networks (maybe of different architecture) can be connected together.
File Transfer protocol specified - how computers send receive data.

1974 - Packets become mode of transfer.

Transmission Control Program (TCP) specified. Packet network Intercomminicaton the besis of Internet Communication.
Telnet, a commercial version of ARPANET, opened - the first publick packet data.

1979 - News Groups Born.

Computer Science Department research computer network established in USA.
USENET established using UUCP.
USENET still thrives today.
A collection of discussions groups, news groups.
3 news groups established by the end of the year.
ARPA establishes the Internet Configuration Control Board (ICCB).
Packet Radio Network (PRNET) experiment stars with ARPA funding. Most communication take place between mobile vans.

1981 - Things start to come together.

CSNET (Computer Science NETwork) established to provide networking services (specially E-mail) to university scientists with no access to ARPANET. CANET later becomes known as the Computer and Science Network.

1982 - TCP/IP defines future communication.

DCA and ARPA establishes the Transmission Control Protocol (TCP) and Internet Protocol (IP), as the protocol suite, commonly known as TCP/IP for ARPANET.

1983 - Internet gets bigger.

Name server developed.
Large number of nodes.
Hard to remember exact paths
Use meaningful names instead.
Desktop workstations come into being.
Internet Activities Board (IAB) established, replacing ICCB.

1984 - Growth of Internet Continues.

Number of hosts breaks 1,000.
Domain Name Server (DNS) introduced.
Instead of 123.456.789.10

1986 - Power of Internet Realised.

5,000 Hosts. 241 News groups.
NSFNET created (backbine speed of 56Kbps)
NSF establishes 5 super-computing ventres to provide high-computing power for all - This allows an explosion of connections, especially from Universities.
Network News Transfer Protocol (NNTP) designed to enhance Usenet news performance over TCP/IP.

1987 - Commercialisation of Internet Begins.

Number of Hosts 28,000

1.1.2. Internet and World Wide Web era

1991 - Birth of WWW

World-Wide Web (WWW) released by CERN, Tim Berners-Lee Developer.
Originally develpes to provide a distributed hypermedia system.
Easy access to any form of information anywhere in the world.
Initially non-graphic (this came later, MOSAIC. 1993).
Revolutionized modern communications and even our way of life.

1992 - Multimedia changes the face of the Internt

Number of hosts breaks 1 Million. News groups 4.000
Internet Society (ISOC) is charteres.
First MBONE audio multicast (March) and video multicast (November).
The term "Surfing the Internet" is coined by Jean Armour Polly.

1993 - The WWW Revolution truly begins

Number of Hot 2 Million. 600WWW sites.
InterNIC created by NSF to Provide soecific Internet Services

Directory and database services

registration services

information services

Business and Media really take notice of the internet.
US White House and United Nation (Un) comes on-line.
Mosaic takes the Internet by strom.

User Friendly Graphical Front End to the World Wide Web.

Develops into Netscape

WWW proliferates at 341.634.

1994 - Commercialisation Begins

Number of Hosts 3 million. 10,000 WWW sites. 10,000 News groups.
ARPANET/Internet celebraes 25th anniversary
local communities begn to be wires up directly to the Internet (Lexington and Cambridge, Mass, USA)
US Senate and House provide information servers
Shopping malls, bamks arrive on the Internet

A new way of Life

You can now order pizza from the Hut online in the US

First Virtual, the First cyberbank, open up for business

NSFNET traffic passes 10 trillion bytes/month
WWW edges out telnet to become 2nd most popular service on the Net (behind ftp data) based on % of packets and bytes traffic distribution on NSFNET
UK's HM Treasury on-line (http://www.hm-treasury.gov.uk/)

1995 - Commercialisation continues space

6.5 million Hosts, 100.000 WWW Sites.
NSFNET revets back to a research network. Main US backbone traffic now routed through interconnected network providers
WWW surpasses ftp-data in March as the service with greatest traffic on NSFNet based on packet count, and in April based on byte count
Traditional online dialup systems (Compuserve, America Online, Prodigy) begin to provide Internet access.
A number of net related companies go public, with Netscape leading the pack.
Registration of Domain names is no longer free.
Technologies of years : WWW, Search engines (WA/S development)
New WWW technologies Emerge Technologies

Mobile code (JAVA, JAVAscript, ActiveX)

Virtual enviroments (VRML)

1996 - Microsoft enters to WWW

Internet phones catch the attention of US telecommunication companies who ask the US COngress to ban the technology (Which has been around for years).
The WWW browser war begins, fought primarily between Netscape and Microsoft. has rushed in a new age in sofware development, whereby new releases are made quarterly with the help of internet users eager to test upcoming (beta) versions.

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1. Introduction to the Internet & WWW

1.1. background & History

1.1.1. Internet history in brief

1.1.2. Internet & World Wide Web era

1.2. The Architecture of the Internet

1.3. Addressing and naming on the Internet

2.The World Wide Web

2.1.The Idea of hypertext and hypermedia

2.2. Common Browser Technologies

2.2.1. Uniform Resource Identifier (URI)

3. HyperText Markup Language