Ajax, which consists of HTML, JavaScript™ technology, DHTML, and DOM, is an outstanding approach that helps you transform clunky Web interfaces into interactive Ajax applications. The author, an Ajax expert, demonstrates how these technologies work together -- from an overview to a detailed look -- to make extremely efficient Web development an easy reality. He also unveils the central concepts of Ajax, including the XMLHttpRequest object.

Old technology, new tricks...

When it comes to Ajax, the reality is that it involves a lot of technologies -- to get beyond the basics, you need to drill down into several different technologies (which is why I'll spend the first several articles in this series breaking apart each one of them). The good news is that you might already know a decent bit about many of these technologies -- better yet, most of these individual technologies are easy to learn -- certainly not as difficult as an entire programming language like Java or Ruby.
Here are the basic technologies involved in Ajax applications:

• HTML is used to build Web forms and identify fields for use in the rest of your application.
• JavaScript code is the core code running Ajax applications and it helps facilitate communication with server applications.
• DHTML, or Dynamic HTML, helps you update your forms dynamically. You'll use div, span, and other dynamic HTML elements to mark up your HTML.
• DOM, the Document Object Model, will be used (through JavaScript code) to work with both the structure of your HTML and (in some cases) XML returned from the server.

Graphic design: Graphic design can make or break a Web site. In fact, the Web as we know it didn't really gain popularity until the Mosaic browser introduced image elements to the Web. But there are a few things that you should know about the use of images. Most important, you should know when to create a GIF or a JPEG and the difference between the two.

Content Design: The individual(s) that design a Web site are often not creating the content for that site. But designers are still responsible for the organization and layout of the content. Ensure that the content is Web appropriate -- if you are handed the equivalent of a 20 page paper, you may want to break it up into smaller pieces with direct access to each piece, while also providing a link to a printable version that contains all 20 pages.

Navigation Design: The best way to design the navigation of a Web site is very low tech -- make a flow chart on a piece of paper. Create (if you haven't already) categories, and subcategories, and assign your content to the appropriate spots. Once you have it all mapped out, ask a lot of end-user questions to see how well your navigation design flows.

Cross-browser Compatibility: Web pages can display differently in different browsers (like Netscape and Microsoft) and in browser versions (Netscape 3.0 and Netscape 4.0). As mentioned above, an understanding of HTML is vital. Different browsers and browser versions offer different challenges when designing a Web page. For example, if you were to add a <bgsound> tag to a Web page to play a background sound, the tag would be ignored completely by Netscape browsers. If you were to add the <layer> tag to create divisions in a Web page, only Netscape 4.0 or above would recognize the tag. All of the other browsers would ignore the tag and display the contents in a jumbled mess.

Color on the Web: Probably the most common novice Web design mistakes involve color. You can use so much of it -- in so many places -- that you end up with garish, distracting, hard-to-read pages. For great color on the Web information, visit the Color Test Results page, a survey designed to measure the readability of various text/background color combinations. (Black text on a white background was rated the best, red text on a green background was rated the worst.)

Publishing Mechanisms: Creating and producing the Web content is not the end of Web site creation. A Web designer must understand the mechanisms of transferring the content to the Web server. (A Web server is the computer that serves the Web pages to the Internet.) The Web server will be hosted by an Internet Service Provider (ISP), which can be inside or outside the company generating the content. The ISP will decide the mechanism or protocol used to transfer your Web pages to the server. Most ISP's offer the File Transfer Protocol (FTP).

A Web Designer is rarely a Webmaster: The Division of Labor: There are lots of titles for Web professionals, and you need to be able to match the title with the responsibilities. This is a new field, and the lines between job descriptions are blurred. A few individuals can do it all, and many perform a combination of these functions.

Generally, Web jobs break out into 5 categories:

• Webmaster: implies administration of a Web server (and often the machine the server runs on).
   
• Web Developer: indicates some level of programming - database designers,  Java or CGI programmers, etc.
  
• Web Designer: creates the overall look and feel of a Web site -- coordinates and participates in the design of site navigation, graphics and content.
  
• Content Creator: generates the content of a Web site -- be it advertising copy, marketing materials, news items, or scholarly articles.
  
• Site Maintenance: the unsung Web workers -- updating links, E-mail addresses, and making small changes in content and navigation.

Have a nice day!