Articles by Kurt Cagle

Real-World AJAX Book Preview: Combining Components and Services

Fri, 30 Mar 2007 10:00:00 EDT

With the above feed service, incredible possibilities are opened up for the XInclude component discussed earlier. In essence, the XInclude component becomes a newsfeed reader, displaying the contents of the newsfeed either as a list of numbered entries or showing just one 'page' of that feed. Note that the contents here are just the summaries of the pages, not (in general) the pages themselves unless the newsfeeds actually are used to transmit the entire content.

Real-World AJAX Book Preview: Retrieving and Sending File Content

Thu, 29 Mar 2007 11:15:00 EDT

The Web client cannot, in the traditional role of things, provide Web content. Of course, that's not quite true - form content sent to the server either directly via a form post submission, or via an XMLHttpRequest object, are very definitely content being 'served' to the server. The difference here is that the server is a passive entity - it can only send information when it gets a request from a client, while the client is increasingly able to do both. Even that definition begins to break down when you consider that the server can make requests from other servers for content.

Real-World AJAX Book Preview: Digging into the XInclude Binding

Wed, 28 Mar 2007 15:15:00 EDT

The XInclude Binding serves as a good example showcasing how such bindings can be created. If you are familiar with XBL bindings, the one aspect that is missing in the JavaScript version is the use of a specific template. This can be readily overcome within the constructor, especially since, unlike the formally defined binding languages, this approach does not create 'shadow trees,' which are somehow distinct from the rest of the DOM.

Real-World AJAX Book Preview: Instantiating the Bindings

Tue, 27 Mar 2007 11:15:00 EDT

In Mozilla, the XBL binding language (an XML language) is used to associate bindings with their respective elements, with these tied in via CSS. Unfortunately, there are no clean hooks for adding a binding in this way for Opera (and a different mechanism for handling it in Internet Explorer).

Real-World AJAX Book Preview: Binding.xhtml

Mon, 26 Mar 2007 09:00:00 EDT

The first thing that may strike you as you're looking at this code is the fact that there is no inline scripting; the page as given is entirely XML driven. The presentation was handled by a simple CSS file included in the style block (which could have also been handled by a element) (jsbinding.css)

Real-World AJAX Book Preview: The Drawbacks to Inline AJAX

Sun, 25 Mar 2007 09:00:00 EDT

The use of JavaScript as a scripting language has emerged primarily in response to this largely monolithic approach to extensions and components. Similarly, the use of the HTML (and later, XML) DOM provided the hooks by which each particular tag could be treated as its own internal component. This approach, the finite set approach, has meant that so long as the underlying browser implementation has support for a given feature, one can create more elaborate structures that essentially built upon this fixed set. Much of the existing AJAX methodology is ultimately built around this particular view of Web programming.

Real-World AJAX Book Preview: The Effects of AJAX

Fri, 23 Mar 2007 09:00:00 EDT

Every so often a new way of developing software comes along, a different approach in design methodology that takes advantage of recent advances in technology to more effectively create applications. Typically, the first efforts to use the technology is to try to build things that are similar to older technologies. But over time, the possibilities opened up by that technology open up new design methodologies and a new understanding of what the technology is capable of doing.

Real-World AJAX Book Preview: A Brief Note on JSON

Thu, 22 Mar 2007 15:00:00 EDT

The object notation used by JavaScript has made its way into a way to transmit structure better in a number of different languages. JSON (JavaScript Object Notation) has gained a fair amount of interest as a somewhat lighter-weight alternative to XML, especially when used across pipes for AJAX transmission.

Real-World AJAX Book Preview: Seeing XML with Serialization

Wed, 21 Mar 2007 15:00:00 EDT

The flip side of parsing is serialization, which, in the loosest sense, is the conversion of an object from an internal representation to some (possibly text) format that can be reloaded in the future.

Real-World AJAX Book Preview: Parsing and Serialization XML

Tue, 20 Mar 2007 15:00:00 EDT

Parsing and serialization were touched on briefly in the discussion of innerHTML, but both issues deserve more extensive coverage. A significant amount of work with AJAX-based systems involves converting strings of XML text into some form of DOM representation, a process formally known as XML parsing, or the reverse process of converting the DOM representation back to text, known formally as XML serialization.

Real-World AJAX Book Preview: Working with Asynchronous Server Content

Mon, 19 Mar 2007 15:00:00 EDT

One advantage comes from learning to work with JavaScript code asynchronously - it makes explaining the XMLHttpRequest object, arguably the cornerstone of AJAX, much easier.

Real-World AJAX Book Preview: Building an Asynchronous Object Registry

Sun, 18 Mar 2007 14:00:00 EDT

This approach, while simple, has a couple of major problems that makes it less than perfect for library functions. One of the first is the fact that the setInterval() and setTimeout methods may be invoked even after a page (or the browser) is closed.

Real-World AJAX Book Preview: Playing with User Interfaces

Sat, 17 Mar 2007 14:00:00 EDT

For a long time user interface development has gotten something of a bum rap with the programming community, in great part because such programming usually doesn't involve high-performance computing, complex mathematical algorithms, or the manipulation of large sets of data.

Real-World AJAX Book Preview: Reviewing the HTML Document Object Model

Fri, 16 Mar 2007 14:00:00 EDT

Up to this point, the discussion has focused on JavaScript exclusively. However, it's reasonable to assume that if you're involved in AJAX development, you'll almost certainly be working in the context of an HTML or XHTML page.

Real-World AJAX Book Preview: Understanding Browser Differences

Thu, 15 Mar 2007 14:00:00 EDT

There's an interesting phenomenon going on right now. Several of the critical technologies used by AJAX first appeared in Microsoft's Internet Explorer, which still has a large (though diminishing) market share according to most statistics.

Real-World AJAX Book Preview: Getting Expressive with Regular Expressions

Wed, 14 Mar 2007 14:00:00 EDT

Regular expressions (or Regexes, as they are sometimes called) provide a way of defining text patterns that can be used for validation, testing, and string replacement.

Real-World AJAX Book Preview: String Theory

Tue, 13 Mar 2007 14:00:00 EDT

Strings, like arrays, are objects, though because of their ubiquity and the way they're declared, it's sometimes easy to lose sight of this. Strings can be created either by using the String() object or via the single or double quotes

Real-World AJAX Book Preview: Counting on JavaScript Arrays

Mon, 12 Mar 2007 14:00:00 EDT

Objects (and object functions) are remarkably useful things, but there are times when all you're really concerned about is a list of items. List manipulation can be found at the heart of any number of sophisticated languages so it's probably not surprising to discover that JavaScript actually has quite a powerful toolset of array capabilities.

Real-World AJAX Book Preview: From Objects to Functions

Sun, 11 Mar 2007 14:00:00 EDT

The function is one of the most fundamental blocks in any language, but in JavaScript the function is in many respects far more powerful and pervasive than it is in nearly any other language. Indeed, the degree to which you can work with functions in JavaScript begins to approach what can be done in languages such as LISP, Haskell, Prolog, and other 'functional' languages.

Real-World AJAX Book Preview: Working with JavaScript Objects

Sat, 10 Mar 2007 14:00:00 EST

Objects are possibly an odd place to start when talking about JavaScript, but if you understand exactly how JavaScript handles objects, you'll have one of the most powerful tools possible for working with AJAX-based components.

Real-World AJAX Book Preview: Some Basic JavaScript Tools

Fri, 09 Mar 2007 14:00:00 EST

Learning JavaScript can be a pain, largely because in most cases you're either limited to working in the browser's command line or building JavaScript in script blocks and leaning heavily on the refresh button in a browser. While JavaScript command-line environments are available, one of the more useful is an extension to the Firefox browser.

Real-World AJAX Book Preview: The Essential AJAX Pieces

Thu, 08 Mar 2007 21:45:00 EST

AJAX isn't so much a single technology as it is a set of technologies that are now all part of most contemporary browsers. Because of this factor, it's sometimes difficult to explain what precisely AJAX is, especially the degree to which XML or JavaScript predominates.

AJAX on the Enterprise

Thu, 25 Jan 2007 17:15:00 EST

In Star Trek, Scotty James Montgomery Scott was my favorite character, perhaps inevitably. Spock was always the cool and collected uber-genius, inscrutable and forced into an emotional straightjacket, and while the parallels to the real politik of the time are obvious, to me Spock has always been the epitome of the pure ivory tower researcher. Scotty, on the other hand, was the enginee , in many ways the ultimate hacker. Spock may have been able to tell you what properties of dilithium would induce warp speed, but Scotty knew exactly how to crack the damn crystals in such a way as to eke out that last 0.5 warp factor necessary to escape the baddies chasing the Enterprise.

AJAX on the Enterprise

Thu, 11 Jan 2007 18:15:00 EST

The efforts going on on the Web right now are not a radical revision of the past, but rather a refinement and 'refactoring' that is at the heart of nearly every software endeavor, and it is this refactoring, far from obvious for those in the thick of it but profound nonetheless, that is insuring the integrity of the Web

The Real Niche forWeb Services: Part 2

Fri, 30 Nov 2001 00:00:00 EST

Last month, in Part 1 of this article, I cautioned about the potential invasiveness of Web services. It's a scary thought that companies could have that much personal information about their customers, but I added then that there are some advantages to Web services, especially in the area of business-to-business. This month I focus on these advantages.

XML Query and the Next Generation Web

Tue, 20 Nov 2001 00:00:00 EST

Anyone who has ever done a search query on the Internet is familiar with the phenomenon in which a single query pulls up more than a million possible search matches. This has to do with the fact that information is ultimately not linear, but rather is linked and interrelated in ways that can't be quantified easily through text searches.

Rethinking Web Services, Pert 1

Sun, 21 Oct 2001 00:00:00 EDT

I've been at this game for a while, a fact that has been hammered into my awareness with distressing frequency of late. I worked with Hollerith cards in college, running my programs through a machine with a distressing tendency to shred my carefully typed code into so much confetti if the deck was not perfectly aligned in the bin. I can remember a time when mentioning the object-oriented programming paradigm was a sure invitation to fisticuffs between its adherents and the old guard. In fact, SQL hadn't even been conceived when I went through college.