It's been approximately 18 months since Jesse James Garrett fatefully coined the term that would go on to nearly reinvent the face of Web development.  A lot has happened in the last year and a half, including the Web 2.0 phenomenon getting into high gear, the creation or resurrection of many a company building or using rich Internet technologies, and the proliferation of really great dynamic, online software.  It's clear that Ajax as a name, a concept, and a popular browser development technique is here to stay, and our Web applications will never be the same again.

While most of us know that the Ajax approach was fairly well known before the term ever came about, the timing was apparently just right for the idea of Ajax to capture our imagination and apply such a pithy name to an important new development trend.  And just as powerful browsers, high-speed connections, online software trends, and development tools were reaching the sweet spot that needed to form for Ajax to be popular, so also came the embrace of a world extremely interested in turning their boring, static Web pages into full-blown, sophisticated applications.  Since then, I've heard of or seen literally hundreds of Ajax products, tools, utilities, debated the disruptive potential of Ajax, speculated about how Ajax will be the face of our SOAs , and even watched as RIA technologies in general have risen up that truly complement the few things that Ajax does not do well, such as multimedia.

Along the way, the Web development community has learned a lot about Ajax including its strengths and weaknesses, appropriate uses, and its inevitable foibles.  So to inaugurate the first print edition of a dedicated Ajax print periodical (see below for details), I thought I'd share my perspective on what I think we've learned in our 18 month journey to remake the face of the Web and the browser.  Ajax has indeed helped give us the next major new platform for software, almost certainly forever surpassing our desktop operating systems as place we develop and use most of our software applications, consumer and business both.  As always, this merely represents my opinion...

What Every Software Project Needs to Know About Ajax

1.  The Browser Was Never Meant For Ajax.  About a week into your first Ajax serious application you'll discover that Ajax pushes the browser nearly beyond its limits and there are definite lower engineering tolerances to get used to. The fact is, without powerful 3rd party development tools, designing clean Javascript software of any size requires some genuine discipline and effort.  So too does Ajax debugging applications in multiple browsers (a real headache), and doing any serious background processing or threading can require heroic measures, particularly if you're mixing in other components that use the rather limited number of simultaneous timers available.  The good news: Simple Ajax -- sprinkling in a little DHTML -- is much less daunting than Ajax In The Large.  But be warned and be prepared to scale up your level of development and testing effort significantly with each doubling or trebling of your application size.
2. You Won't Need As Many Web Services As You Think.  I used to think that going the Ajax route required the development of a bunch of new Web services in order to feed the application data and provide a backing store.  In reality, I'm finding a great many projects are quite happy to scrape HTML and/or use plain old HTTP POSTs to existing service endpoints that have no formal Web service structure.  This is further turning the tide towards Ajax by making it very, very easy to "dip your toe" into Ajax development and reuse almost any preexisting HTTP service on the back end instead of SOAP or REST/WOA.  While this can encourage poor architectural choices, it does make very incremental conversion to Ajax almost effortless and turns out to be a natural thing to do, though it can certainly lead to headaches later.
3. Ajax Is More Involved Than Traditional Web Design and Development.  The loss of HTML user interface conventions, the almost limitless potential for hidden or latent functionality, the programmatic creation of page elements instead of declarative, and other intrinsic aspects of the Ajax approach throw out much of what we know about Web design and development.  Web designers must much more deeply understand the capabilities of the DOM, Javascript, CSS, and how the browser renders graphics, layouts, and elements.  Developers find testing both difficult and tedious.  Though tooling is continuing to improve across the board, it will take years for the industry to develop best practices, lore, patterns, and shared knowledge to make Web application development straightforward.  Huge kudos to folks like Yahoo!'s Bill Scott for trying to fix many of these problems -- particularly the loss of GUI standards -- by actually moving the state of the art considerably forward with things like the Yahoo! UI Design Patterns library.  The bottom line: Ajax development, at least for now, usually takes quite a bit longer than traditional Web development and requires a higher level of skill.
4. Ajax Tooling and Components Are Still Emerging and There Is No Clear Leader Today.  Though Dojo is getting one heck of a running start, the race is very far from over.  For instance, the Dojo framework itself is still just at version 0.3.  And close at its heels are an amazing range of tools, frameworks, and component libraries.  Though OpenAjax will make this mosaic of products play nicer, most developers will get deep experience with two or three of them and stick with them. For now, I would say deeply committing to a particular product is usually not the best idea.  Innovation, competition, and market leadership is likely going to bounce around for a while.  In the meantime, be sure to check out script.aculo.us, Prototype, Google Web Toolkit, Yahoo! UI Library, JackBe, Zapatec, Bindows, Nexaweb, General Interface, Backbase, ActiveWidgets, and last but not least Microsoft Atlas. There are many others and I encourage you to look at Max Kiesler's roundup of 50 Ajax frameworks, with many others in the comments (and growing).  Finally, Microsoft's Harry Pierson has diligently taken me to task for my Ajax spectrum comments, noting that Microsoft actually has more serious experience fostering an interoperable component community than just about anyone else.
5. Good Ajax Programmers are Hard to Find.  Zimbra's Scott Dietzen has lamented recently about the real difficulty in finding good Ajax talent.  See point #3, but building sophisticated Ajax applications requires more computer science skills much more than it does Web design skills.  And I find that experienced programmers tend not to enjoy Javascript programming and debugging. This too shall pass, but not for a few years, and not for a good while in the Bay Area. :-)
6. One Must Actively Address Ajax's Constraints of the Browser Model.  Though the final result can be very rewarding, Ajax is not a perfect Web development approach and it has a few genuine weaknesses.  One is that it tends to break the model of the Web including preventing users from bookmarking content, breaking the use of the Back button, and more.  Fortunately, smart folks like Brad Neuberg have addressed much of this, as long as you're willing to put out the effort and understand why it's important to recover this functionality.  Ajax also lacks much of what still makes desktop software a strong contender; the ability to run disconnected from the network and access to local disk storage, though Flash local storage and the upcoming Apollo platform can help address this.
7. Ajax Is Only One Element of a Successful RIA Strategy. As I've written before, the addition of RIA platforms such as Flex, OpenLaszlo, and WPF/E to a RIA strategy is virtually required to properly exploit the range of capabilities you'll want robust online applications to have.  This is particularly true around rich media support such as audio and video -- which Ajax is virtually incapable of -- but even such mundane things as good printing support.  These are all things that the more sophisticated Flash-based RIA platforms really shine at and are easier to program in to boot.  Ajax will increasingly get a serious run for its money from these platforms, particularly as they provide back-end server support for things like server-side push, formal Web services, enterprise environments, and more.

There are certainly other things software projects should know about Ajax but this is plenty of crucial food for thought.  Looking ahead, we see the growing trend of in-browser mashups which is making the habit of combining pulling together -- entirely on the fly -- sets of Ajax components, Javascript snippets, and Flash widgets from all over the Web into a new set of often user-generated ad hoc software .  Backed by the growing Global SOA , online Ajax components such as Google Maps, that can be referenced over the Web by a line of Javascript, and you have a recipe for an increasingly emphasis on assembly and glue instead of "green field" development of RIAs.  This is an important use of the Web that I've called the "mashosphere " for the lack of a better term, which ushers in a whole new era of dependency and configuration management problems.  The rich palette of software components and high value services on the Web will be a irresistable siren call for developers and expect more and more Ajax applications to be mashups in one form or another.

But all of this talk of the evolution of Ajax does bring up some exciting new industry events... 

Announcing The Premier Issue of AjaxWorld Magazine - Print Edition 

Please do pardon the shameless self-promotion here at the end of this piece, but this is also important Ajax community news.  I've been the editor-in-chief of SYS-CON's AjaxWorld Magazine for a while now and to herald the rise of Ajax, we've just expanded it to a full blown print magazine with the premier issue coming out at the all-star AjaxWorld Conference and Expo and Ajax Bootcamp next week in Santa Clara, California.

For the cover story of the premier print issue, I worked with the OpenAjax Alliance -- a big thanks to IBM's Jon Ferraiolo and Joseph Becker -- to get a premium article series on both the strategic and technical direction of this significant and important new development in the Ajax world.  OpenAjax holds the promise of true Ajax component interoperability, consistent tool support, and much more.  I've urged Microsoft to consider joining -- they're one of the major holdouts -- and they've promised to seriously consider it after they get Atlas shipped, so hopefully we'll see nearly 100% industry support soon.  Thus, the story of OpenAjax has been one of the bigger Ajax stories of the year as the number of vendors on board continues to grow in leaps and bounds, never mind the relatively light hand and welcome avoidance of a heavyweight standards approach to Ajax interoperability.

I'll be blogging more about Ajax and less about Web 2.0 here in the next week or so as coverage of AjaxWorld and the many exciting announcements and information begins to flow forth.

Happy Ajaxing and hope to see you next week in California!