Download HTML HyperText Markup Language

WEB SITE DEVELOPMENT
OVERVIEW
Web Site Development Module Overview
• Lectures
– Lecture 1
• Web Site Technology Foundation
• Developing a Web Site
• HTML Overview
– Lecture 2
• HTML Continued
• Cascading Style Sheets
• Labs
– Lab 1
• Basic tools for developing a web site
• Creating a Home Page using HTML
– Lab 2
• More practice with HTML
• Extending your web site using Cascading Style Sheets
– Semester Project Assignment and Kickoff Lab
Web Site Development
• Building and maintaining a web site utilizes the same basic disciplines as
developing and maintaining applications programs
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Requirements – Defining and gaining agreement on the problem being solved
Design – Deciding on the approach to solving the problem
Development – Building the solution
Testing – Ensuring the solution works under varied conditions
Implementing/Publishing – Making the solution available to the users
• Web sites utilize a series of innovations for:
– Formatting and presentation of documents (web pages)
– Navigating within and between documents
Hypertext
• Text that includes links – no single sequential path through or
between text documents
• Long history that could go back as far as the Talmud
• 1945 - Vannar Bush
– Described a system for linking microfilm machines
– System was called Memex
• 1965 Ted Nelson working at SRI
– Coined the terms hypertext and hypermedia
• 1977 - First hypermedia use was a tour of Aspen
• 1983 – Hypermedia development tool available on an Apple II
• 1987 – Apple release Hypercards for the Macintosh
Links Can Be Followed Ad Hoc
Markup Languages
• A Programming Language is compromised of a set of rules
that direct the actions of a computer
• A Markup Language is a programming language designed for
formatting of “documents” where a document can be any stored
file, not just text
• The formatting is defined in the document as a series of tags
• 1960s – IBM
– Standardized General Markup Language (SGML)
– Formatting of documents to be printed
– Many of the earliest tags still in use in Markup Languages today
There Are a Number of Markup Languages
• SGML – Standard General Markup Language
– Text document formatting had no hyperlinks
• XML – Extensible Markup Language
– Language that describes document format and context
– Commonly used for inter-program, document exchange
– Used in business between companies (or within) for Electronic Data Interchange
(EDI) . E.g. to send an invoice to another company’s computer I would encode it
in XML.
• HTML – Hypertext Markup Language
– One of the original languages used to format web pages
• XHTML – Extensible Hypertext Markup Language
– Strict interpretation of Hypertext rules
– All open tags must be closed and tags must be properly nested
• Cascading Style Sheets
– Allows the separation of formatting from the actual page contents
– Uses many HTML concepts, and eclipsing HTML
Hypertext Markup Language (HTML)
• The Combination of Hypertext and Markup Languages
• Origination credited to physicist Tim Berners-Lee
– Working at CERN (European Organization for Nuclear Research)
– Looking for method for scientists to share information between
networked computers
– First used in December 1990
• Using document elements (tags) to link (jump to) related
documents within or between computers
Browser
• A program that is able to interpret and act on the contents of documents
encoded with HTML or other language with a similar intent
• 1992 University of Kansas
– Lynx browser
– Used for student campus information – text only
• 1993 University of Illinois
– First browser to support both text and graphics information
– Mosaic browser whose co-author was Marc Andreesen
• 1995 Netscape IPO
– Founding members were Jim Clark and Marc Andreesen
– Primary products the Netscape browser and web server (based on Mosaic)
• 1995 Internet Explorer 1.0
– Initial browser from Microsoft who licensed the software from Spyglass
• 1996 Internet Explorer 3.0
– Equivalent Netscape functionality bundled with Windows 95
HTML
• HTML is made up of instructions embedded in a document that inform a
browser how to treat a document
• The instructions are expressed as tags and attributes which further define
the tag instruction
• HTML tags are:
– Delimited by greater and less than symbols < and >
e.g. <b> indicates the text that follows is to be bolded
– And should generally bounded by open <tag> and close tags </tag>
e.g. <b>This text will be in bold</b>
– In a few cases there are multiple tags for the same function, e.g.
<b>, <em> and <strong> do the same thing.
• Attributes further qualify tags that require information
<img src=“name”>
This tag indicates that an image is to included where src=“name” indicates
the location of the image (e.g. file path)
HTML
• Basic tag language rules
– Whitespace (blanks, new lines) insensitive
Hello there is treated the same as He llo the
re
– Attribute values can be enclosed in single or double quotes (i.e. ‘ or “)
– Not all tags require attributes
– Not all attributes require quotes
– Not all tags require open and close (but generally a a good habit)
<p>This is the first paragraph <p>This is the second
<p>This is the first paragraph</p> <p>This is the second<p>
Will probably be treated the same
– Beware: HTML does not do checking for errors – it interprets what it can
and ignores the rest. You will need to be the error checker for yourself.
Cascading Style Sheets - CSS
• A Style Language that like HTML, describes the look and formatting of
documents – the most common of which are web pages
• Provides the same types of formatting capabilities as HTML
• CSS:
– Allows for better separation of document content and formatting information
– Can be stored separately from the document’s contents
– Can specify different formatting information for different presentation modes
(e.g. viewing versus printing)
these features:
– Allow content developers to focus on content
– Facilitate sharing of formatting instructions across documents
Javascript
• 1996 - First introduced by Netscape browser Version 2.0
• Code which runs within the client’s browser (on your Mac/PC)
• Relatively easy to learn and use
• Support by “all” browsers
• Allows additional interactive features to users via browsers, e.g.
– Forms controls such as field validation
– Allowing mouse-rollover to change an object
– Popping a new window and controlling the size of the window
• Disadvantages
– Users can disable
– Common carrier for malware
Planning for a Web Site
What Do You Think Makes a Good Web Site?
Planning for a Web Site
Some considerations:
• Be clear on the audience, purpose and requirements
• Plan your sites look and feel
– Be consistent
– Be clear
– Use of fonts, color, graphics, sounds and video
• Set and test page loading speed for acceptability
• Plan the structure and hierarchy of your pages
– Within a page
– Between pages
• Plan your navigation
– Within a page
– Between pages
– Between your site and other sites
• Create a mockup and check with users
Process for Developing a Web Site
• Complete the planning
• Create the web pages using an editor or other tool
– There are many editors that assist in creating web pages (free and fee)
– We will use the Notepad Accessory which is part of Windows – it doesn’t provide
any assistance
• Test the web pages locally
• Publish the web pages by uploading the pages to the web server
– There are many tools available to facilitate the management and uploading of web
pages – called content management systems
• Commercial web sites:
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First publish to test web sites
Ensure that all pages work well on all browsers they intend to support
Test page load times across a variety of user internet connections for acceptability
Tune and retest as needed
Push to the public-facing web sites
A Basic Approach toWriting Code - Programming
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Document the problem you want to solve
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Sketch out your ideas
– Basic flow
– Web page or report layouts
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Write the code with your tool of choice
– Do it incrementally
– Testing:
• Each new section as you add
• Prior sections to ensure you haven’t broken them
• Thoroughly test
– Test each function
– Test the system end to end
– If appropriate stress test
Your goal is to break your code!
– Rather than a user finding your faults
– So you can fix it