Avoid Unnecessary Ajax Traffic with Session State

Where possible, creating Web applications -- including Ajax-based applications -- in a RESTful way avoids a large class of bugs. However, a pitfall of REST (REpresentational State Transfer) is sending duplicate data across similar XMLHttpRequests. This tip shows how the moderate use of session cookies can maintain just enough server-side state to significantly reduce client-server traffic, while still allowing fallback to cookie-free operation.

Mertz, David. IBM (2007). Articles>Web Design>Programming>Ajax

Getting Started with the DocBook XML Dialect

Gets you started with DocBook, an SGML/XML dialect that describes the content of technical articles and other documents. David discusses the benefits of using DocBook, and then describes how to plan and modularize a large document conversion project.

Mertz, David. IBM (2000). Articles>Documentation>XML>DocBook

GUIs and XML Configuration Data

Discusses how XML is used in the configuration of GUI interfaces. He looks at Mozilla's XML-based User Interface Language (XUL) which allows you to write applications that run without any particular dependency on the choice of underlying operating system. This may seem strange at first, but you'll soon see that this Mozilla project offers powerful tools for GUI building that allow you to develop for an extensive base of installed users.

Mertz, David. IBM (2004). Design>Web Design>User Interface>XML

Make the Best Use of Asynchronous Callbacks

It takes some finesse to make the best use of asynchronous callbacks for Ajax data sources in JavaScript applications. This tip discusses why you should use asynchronous callbacks for Ajax data sources and gives examples of coordinating the readiness of mutually dependent application data sources that may become ready at undefined times with asynchronous calls.

Mertz, David. IBM (2007). Articles>Web Design>Programming>Ajax

Pay Attention to the CSS @media Rule: When to Define the Screen Media Type

The CSS @media rule is a useful way to target an HTML or XML document to an intended output device. Use of the print media is now fairly widespread, and provides a much cleaner means of creating printer-friendly pages than does a separate 'printable version.' The use of the screen media has been somewhat underused, perhaps because of an overly general assumption that screen is merely the 'default rendering.' However, in regard to positioning--especially absolute positioning--the screen media type has an important meaning that is not covered by media-free stylesheet rules.

Mertz, David. IBM (2007). Design>Web Design>CSS

Program with SVG

Scalable Vector Graphics (SVG) is an XML format that describes scale-independent graphics, with good support in free software and commercial tools. In this installment, David introduces scripting and animation with SVG, and touches on manipulating SVG through DOM. Because SVG is XML, it lends itself to transformation and/or generation with any of the tools and libraries you might use for XML generally.

Mertz, David. IBM (2005). Design>Web Design>Graphic Design>SVG

Ten (or a Few More) Files Every Web Site Needs

Regardless of what sort of Content Management System or Web application framework you might use to develop your Web site, there are some basics you should cover. A sophisticated user interface and rich content is great to have, but before you get to that, you should provide the basic files that users anticipate finding and that tell both humans and machines what your site does.

Mertz, David. IBM (2007). Design>Web Design

Why (Almost) Every Web Site Needs an RDBMS

When your Web application reaches a certain size, it needs a good database design behind it. And in fact, this 'certain size' is much smaller than almost every small-site developer thinks. Relational Data Base Management Systems (RDBMSes) need not be restrictive or over-architected, as their bad reputation sometimes brings developers to fear. A bit of thought toward what your site does quickly turns into a sensible schema design, and it is easy to leave open expandable storage mechanisms like a configuration table within an RDBMS back end.

Mertz, David. IBM (2007). Articles>Web Design>Server Side Includes>Databases