XHTML, CSS , Good web and database design practices

XHTML, CSS , Good web and database design practices Snehal Monteiro For CIS 764

Outline • What You’re In For • Why XHTML & CSS? • XHTML • CSS • Making the Transition • The Future • Good Web and Database design practices

What You’re In For • This presentation focuses mainly on the front-end i.e. the web-pages of an enterprise database application • XHTML and CSS are the latest trends in web design and play a major role in enhancing the usability of the application

Why XHTML & CSS? • Garbage code is…uh…garbage! • Information encoded in XHTML can be more easily migrated as technology changes • XHTML is a good step forward to learning XML • You can easily make global changes to how your documents display • There are user benefits to separating information from presentation

What is XHTML • XHTML stands for eXtensible HyperText Markup Language • XHTML is aimed to replace HTML • XHTML is a stricter and cleaner version of HTML • XHTML is HTML defined as a XML application • XHTML is a W3C Recommendation

XHTML …why? • Many pages on the WWW contain bad HTML • XML is a markup language where everything has to be marked up correctly, which results in "well-formed" documents. • Hand held devices like PDA’s and mobile phones do not have resources and power to interpret bad HTML code • A mark-up language for now and for the future. Future browser versions may support only XHTML…so be prepared!!!

XHTML Benefits • A painless transition to more advanced technology (XML) • Clean, more logical markup • Increased interoperability • Greater accessibility

XHTML-key ingredient in mobile browsing • XHTML reduces the difference between wireless and web content • XHTML Basic and Cascading Style Sheets separate content from presentation enabling content tailoring to different devices Benefits: • Consumers –more services, better userinterface, easier-to-use • Carriers – more control over content,consistent look & feel, service loyalty • Content providers – presentation, functionality,consistency, familiar format • Manufacturers – Easier software maintenance, better performance, lower cost

How can I convert to XHTML??Very few simple rules…that’s it! • All tags must be in lowercase: • <title></title> • All tags must end: • <p></p> • Even empty tags: • <br></br> = <br /> • All tags must properly nest: • <p>This is an <a name=“here”>anchor</a>.</p> • All attribute values must be quoted: • <div align=“center”></div>

XHTML: More Rules • Attribute minimization is forbidden: • <input type=“radio” name=“stuff” CHECKED> becomes… • <input type=“radio” name=“stuff” checked=“checked” /> • You must use a document type declaration:Transitional:<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN""http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> Strict: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> • And add a namespace declaration to <html>: <html xmlns=“http://www.w3.org/1999/xhtml” xml:lang=“en” lang=“en”>

Evolution of XHTML standards • HTML 4.0 Transitional • XHTML Basic • XHTML Transitional • XHTML Strict • There are online validation tools available which check conformance to standards-

Kick It Up a Notch:Enhance your web page with Cascading Style Sheets • CSS is a standard layout language for the Web • Though precise and powerful, CSS is easy to author by hand. • Replace HTML table-based layouts, frames, and other presentational hacks. • Separate style from content

Benefits of CSS • Conserve bandwidth (less markup for visitors to download) • Reduce design/development time • Reduce updating and maintenance time • Increased accessibility (fewer, or no, HTML tables; no invalid junk markup) • Adhere to W3C recommendations, improving interoperability and ensuring greater longevity Better, more professional appearance (line–height, borders, padding, margins) • Increased readability (line–height, borders, padding, margins) • More easily transition in future to more powerful standards such as XML (because page content no longer contains junk markup)

selector declaration ends every property/ value pair property value property/value separator begins and ends the declaration CSS: Rule Structure h1 { color: purple; } h1 { font-family: Optima, Arial, sans-serif; }

CSS Rule Example body { background: #FFFFFF; color: black; margin-left: 5%; margin-right: 5%; font-family: Tahoma, Optima, Arial, sans-serif; }

Where do you put styles? • In-line - add to HTML tag<H1 style="color: maroon"> • Embedded style sheets<style> </style> • External style sheets<link href="style.css">

In-line <H1 style="color: maroon"> • Similar to adding attributes to html tags • Disadvantages • decreased accessibility • increased file size • harder to update

Embedded style sheets <style>  </style> • Put rules between style tags • Put in head section • Add html comment tags • Use when single document has unique style

External style sheets <link rel="stylesheet"type="text/css" href="style.css"> • Save rules in external file • Advantages • ease of maintenance • use less disk space • increase accessibility

Class selector & attribute To create rules that can be applied to a variety of html tags <style>.bar {color: maroon; font-size: smaller; background-color: yellow;}</style> … <p class="bar">text</p>… <p><a href="url.htm" class="bar">link</a> </p>

CSS: Diagram of Precedence XHTML File External Style Sheet 2) [call to external stylesheet] 1) [styles embedded inside the document] Generalized order of precedence, all other things being equal

http://jigsaw.w3.org/css-validator/

Making the Transition: Tidy • HTML Tidy is free software that can read your HTML and output a much better file by: • Automatically fixing some errors • Changing uppercase tags to lowercase • Indenting your code to make to make it more readable • Quote all attribute values • And other things, depends on configuration file • An error report may also be generated that can identify remaining problems

Making the Transition:Migrating an Existing Site • All at once: • Copy entire site to another location • Run Tidy; check and re-run as needed • Clean up remaining problems • Transfer back • Gradual: • Do all new things in XHTML/CSS • Migrate old files as you update them for other reasons

The Future • Will XML replace HTML? • It already has! That’s why you’re here! • XML will typically not be delivered to web clients; that is what XHTML will be for • So, is this the last markup you have to learn? • No way! Use this as a stepping-stone to XML, for which you will have many additional uses • Remember — Never stop learning!

Adding hit counters to your web-site for free • Just register at www.google.com/analytics • Type in the url of your web-site • You will get a javascript code snippet • Just add the code to your index page • You get daily reports about user activity on your site

Good web-design practices: • Comment your code! • Use XHTML rules and CSS • Use AJAX to enhance user interaction and increase speed • Archive code before making any changes to the current web-site • Re-use code: eg: Database connection code, reusable javascript subroutines • Use lower-case more than upper-case, it looks more attractive and subtle

Good database design practices Comment your code! Don’t store big binary files in the database Correctly identify which fields require data If a column storing the same data appears or is referenced in more than one table (e.g. a foreign key), it should have the same data type throughout the database.

Continued… • When running queries on the database, use only the column names that you need to retrieve. This can reduce network traffic and disk operations. • When running an insert action query, use the columns list into which to insert instead of the table name (when you want to insert data in all the current columns). This way, if new columns are added to the table, your query will still work.

References • W3C-Introduction to XHTML http://www.w3schools.com/xhtml/xhtml_intro.asp • NYPL Online Style Guide: XHTML and CSS http://www.nypl.org/styleguide/xhtml/index.html • Better Living through XHTML By, Jeffery Zeldman http://www.alistapart.com/stories/betterliving/ • Good practices in database design http://www.interaktonline.com/Support/Articles/Details

Thank-you! Questions ???

XHTML, CSS , Good web and database design practices