CSc 4370/6370: Web Programming

Basic HTML      hypertext tags & elements text formatting lists, hyperlinks, images tables, frames  cascading style sheets • inline, document, external

Hypertext & HTML

• HyperText Markup Language (HTML) is the language for specifying the static content of Web pages (based on SGML, the Standard Generalized Markup Language)  hypertext refers to the fact that Web pages are more than just text can contain multimedia, provide links for jumping within the same document & to other documents  markup refers to the fact that it works by augmenting text with special symbols (tags) that identify the document structure and content type

Hypertext & HTML (cont.)

• HTML is an evolving standard (as new technology/tools are added)  HTML 1 (Berners-Lee, 1989): very basic, limited integration of multimedia in 1993, Mosaic added many new features (e.g., integrated images)  HTML 2.0 (IETF, 1994): tried to standardize these & other features, but late in 1994-96, Netscape & IE added many new, divergent features  HTML 3.2 (W3C, 1996): attempted to unify into a single standard but didn't address newer technologies like Java applets & streaming video  HTML 4.0 (W3C, 1997): current standard (but moving towards XHTML) attempted to map out future directions for HTML, not just react to vendors  XHTML 1.0 (W3C, 2000): HTML 4.01 modified to conform to XML standards  XHTML 1.1 (W3C, 2001): “Modularization” of XHTML 1.0

 HTML 5 (Web Hypertext Application Technology Working Group, W3C, 2006): New version of HTML4, XHTML 1.0, and DOM 2 (still a work in progress)

Web Development Tools

• many high-level tools exist for creating Web pages e.g., Microsoft FrontPage, Netscape Composer, Adobe PageMill, Macromedia DreamWeaver, HotDog, … also, many applications have "save to HTML" options (e.g., Word)

for most users who want to develop basic, static Web pages, these are fine (but many of these programs produce very poorly structured HTML code)

• assembly language vs. high-level language analogy • so, why are we learning low-level HTML using a basic text editor?

      may want low-level control may care about size/readability of pages may want to "steal" page components and integrate into existing pages may want dynamic features such as scripts or applets remote editing of web pages may only be possible using a basic text editor

sticking to (internationally and industrially) agreed upon standards will help ensure your web documents are rendered as you intend them to look and operate as you desire

Tags and Elements

• HTML specifies a set of tags that identify structure of the document and the content type  tags are enclosed in < > specifies an image  most tags come in pairs, marking a beginning and ending enclose the title of a page • an HTML element is an object enclosed by a pair of tags is a TITLE element This text appears bold . is a BOLD element

Part of this text is bold .

is a PARAGRAPH element that contains a BOLD element

An HTML document is a collection of elements (text/media with context).

Structural Elements

• an HTML document has two main structural elements  HEAD contains setup information for the browser & the Web page e.g., the title for the browser window, style definitions, JavaScript code, …  BODY contains the actual content to be displayed in the Web page

Hello world!

HTML documents begin and end with and tags Comments appear between HEAD and section enclosed between tags BODY section enclosed between and

* Find more info on HTML docs!

view page

and elements

 The element is where you include a

This is a paragraph of text
made up of two lines.

This is another paragraph with a   GAP   between some of the words.

   This paragraph is
indented on the first line

but not on subsequent lines.

view page for the most part, layout of the text is left to the browser  every sequence of whitespace is interpreted as a single space  browser automatically wraps the text to fit the window size can override some text layout  can specify a new paragraph (starts on a new line, preceded by a blank line) using

…

 can cause a line break using the
tag (“self-closing” tag)  can force a space character using the symbol for a “non-breaking space”:  

Separating Blocks of Text

Major heading 1

Here is some text.

Subheading

Here is some subtext.

---

Major heading 2

Here is some more text.

view page can specify headings for paragraphs or blocks of text   

…

bold heading tags produce a large,

…

smaller heading . . .

tags produce a slightly

…

heading tags produce a tiny can insert a horizontal rule to divide sections 

---

draws line across window

The Basic Web page – A Worked Example

Bill Smiggins Inc.

About our Company...

This Web site provides clients, customers, interested parties and our staff with all of the information that they could want on our products, services, success and failures.

---

Products

We are probably the largest supplier of custom widgets, thingummybobs, and bits and pieces in North America.

---

view page

Text Variations

We can use simple tags to change the appearance of text Web pages .

Text Appearance

within Even super ^script can specify styles for fonts      … … specify bold specify italics … specify typewriter like (fixed-width) font … size of the font increase the … the size of the font decrease … put emphasis … even more emphasis put and sub _scripts are   supported .

Text Escape Sequences

& < > " ©

Preformatted text

    …  subscript …  specify a a superscript include ready Department of Computer Science Georgia State University Office: 34 Peachtree St. Suite 2125  
…
 formatted text & &al; > " © escape characters used in HTML control   Telephone: (404) 413-5744 

*

Find more info on text tags!

Lists

• ... first list item...
... second list item... ...

Dweeb

young excitable person who may mature into a Nerd

Hacker

a clever programmer

Nerd

technically bright but socially inept person

1. Makes first item number 30.

2. Next item continues to number 31.

view page there are 3 different types of list elements   

…

item)

specifies an ordered list (using numbers or letters to label each list identifies each list item

can set type of ordering, start index

…

unordered list (using a bullet for each)

specifies identifies each list item

…

definition list specifies a

identifies each term

identifies its definition * We will learn more about the “style” attributes soon enough.

Bismita Jena
Open page07 in a new window

Hyperlinks perhaps the most important HTML element is the hyperlink, or ANCHOR

 … where URL is the Web address of the page to be displayed when the user clicks on the link

if the page is accessed over the Web, must start with

http://

if not there, the browser will assume it is the name of a local file

 … causes the page to be loaded in a new Window

* Find more info on attribute TARGET

Hyperlinks (cont.)

for long documents, you can even have links to other locations in that same document

[ HTML | HTTP | IP | TCP ]

Computer acronyms:

HTML HTTP IP TCP "> "> "> ">

HTML

HyperText Markup Language

HTTP

HyperText Transfer Protocol…

IP

Internet Protocol…

TCP

Transfer Control Protocol…

   … where ident this location is a variable for identifying … will then jump to that location within the file … can jump into the middle of another file just as easily view page

Hyperlinks (cont.)

Internal links are handled slightly differently in HTML 5.

[ HTML | HTTP | IP | TCP ]

Computer acronyms:

HTML

HyperText Markup Language

HTTP

HyperText Transfer Protocol…

IP

Internet Protocol…

id="TCP" >TCP

Transfer Control Protocol…

Use the same format to specify the hyperlinks, but use an ‘id’ to define the location of the anchor. This can be applied to (nearly) any HTML element.

Images

can include images using img   by default, browsers can display GIF and JPEG files other image formats may require plug-in applications for display height= "n" width= "n" alt= "

text

" again, if file is to be accessed over the Web, must start with http:// (if not, will assume local file) * Find more info on " title=“GEORGIA STATE UNIVERSITY" alt=“GSU"

Situated in downtown atlanta

Images (cont.)

 src - specifies the file name (and can include a URL)  width and/or height - dimensions in pixels (often only need to specify one of them and the other is automatically scaled to match)  title - displayed when the mouse is “hovered” over the picture  alt - text that is displayed when the image is missing, can’t be loaded (e.g. if file permissions aren’t set correctly), or if the client has disabled loading images in his/her browser

Tables

• tables are common tools for arranging complex layout on a Web page  a table divides contents into rows and columns  by default, column entries are left-justified, so provide for alignment

A Simple Table

Right Column Some other data

Left Column
	Some data

… element specify a table … specify a row in the table … specify table data (i.e., each column entry in the table)

Layout in a Table

can have a border on tables using the “border” attribute

increasing the number makes the border thicker

Left Column	Right Column
Some data	Some data

can control the horizontal & vertical layout within cells can apply layout to an entire row We will explore this more with Cascading Style Sheets (CSS).

Table Width

left-most

right-most

by default, the table is sized to fit the data can override & specify the width of a table relative to the page For example

Other Table Attributes

can control the space between cells & margins within cells This is the “padding” attribute in the table and th,td style sheet declarations (more on this with Cascading Style Sheets). can add headings

is similar to	but displays heading centered in bold HEAD1 HEAD2 HEAD3 one two three four five six seven can have data that spans more than one column	similarly, can span more than one row	(This example uses CSS style sheet commands in the page .) Frames • frames provide the ability to split the screen into independent parts Frames are going out of fashion, partly because they interact poorly with web search engines (i.e. search engines cannot generally access the data stored in the inset frame objects). Frames can also “break” the regular behaviour of browsers, most notably the “Back” button on the browser can behave in unexpected ways. Because of these drawbacks to frames, I will not be discussing them in this course. If you wish to design websites using frames, I would encourage you to use the XHTML XFrames specifications (see the W3C website for more details), but this specification isn’t fully supported by all browsers at this time. Frames are also not supported by the HTML 5 specification. Content vs. Presentation • Most HTML tags define content type, independent of presentation.  exceptions? (e.g. …… for bold text and ….. for italicized text) • Style sheets associate presentation formats with HTML elements.  CSS1: developed in 1996 by W3C   CSS2: released in 1998, but still not fully supported by all browsers CSS3: specification still under development by the W3C, “completely backwards compatible with CSS2” (according to the W3C) • The trend has been towards an increasing separation of the content of webpages from the presentation of them. • Style sheets allow us to maintain this separation, which allows for easier maintenance of webpages, and for a consistent look across a collection of webpages. Web rules of thumb (ok, my rules of thumb…) • HTML and CSS provide lots of neat features, but just because you can add a feature doesn't mean you should! don't add features that distract from the content of the page  use color & fonts sparingly and be careful how elements fit together e.g, no purple text on a pink background, no weird fonts e.g. I find bright white text on a black background difficult to read  use images only where appropriate e.g., bright background images can make text hard to read e.g., the use of clickable images instead of standard HTML buttons or links can slow access  don't rely on window or font size for layout e.g., font size may be adjusted by viewer, window constrained  don’t be annoying e.g., lots of pop-up windows, excessive advertising, silly music  break a large document into several smaller ones or provide a menu for navigation  stick to standard features and test several browsers if possible (and versions of the same browser)  utilize style sheets to make changes easy & ensure consistency Directory ×