Like a lot of Charlie's blogs, he nails parts of this one squarely on the head:
WORA was, is, and always will be, a fallacy. ... It is the “Write once…“ part that’s the most dangerous. We all wish the world was rainbows and unicorns, and “Write once…” implies that there is a world where you can actually write an app once and it will run on all devices. But this is precisely the fantasy that the platform vendors will never allow to become reality. ...
And, given his current focus on building a mobile startup, he of course takes this lesson directly into the "native mobile app vs HTML 5 app" discussion that I've been a part of on way too many speaker panels and conference BOFs and keynotes and such:
HTML5 is awesome in many ways. If applied judiciously, it can be a great technology and tool. As a tool, it can absolutely be used to reduce the amount of platform specific code you have to write. But it is not a starting place. Starting with HTML5 is the most customer unfriendly thing a developer can do. ... Like many ‘solutions’ in our industry the “Hey, write it once in in HTML5 and it will run anywhere” story didn’t actually start with the end-user customer. It started with idealistic thoughts about technology. It was then turned into snake oil for developers. Not only is the “build a mobile app that hosts a web view that contains HTML5″ approach bass-ackwards, it is a recipe for execution disaster. Yes, there are examples of teams that have built great apps using this technique, but if you actually look at what they did, they focused on their experience first and then made the technology work. What happens when the shop starts with “we gotta use HTML5 running in a UIWebView” is initial euphoria over productivity, followed by incredible pain doing the final 20%.
And he's flat-out right about this: HTML 5, as an application development technology, takes you about 60 - 80% of the way home, depending on what you want your application to do.
In fact, about the only part of Charlie's blog post that I disagree with is the part where he blames Gosling and Java:
I blame James Gosling. He foisted Java on us and as a result Sun coined the term Write Once Run Anywhere. ... Developers really want to believe it is possible to “Write once…”. They also really want to believe that more threads will help. But we all know they just make the problems worse. Just as we’ve all grown to accept that starting with “make it multi-threaded” is evil, we need to accept “Write once…” is evil.
It didn't start with Java--it started well before that, with a set of cross-platform C++ toolkits that promised the same kind of promise: write your application in platform-standard C++ to our API, and we'll have the libraries on all the major platforms (back in those days, it was Windows, Mac OS, Solaris OpenView, OSF/Motif, and a few others) and it will just work. Even Microsoft got into this game briefly (I worked at Intuit, and helped a consultant who was struggling to port QuickBooks, I think it was, over to the Mac using Microsoft's short-lived "MFC For Mac OS" release), And, even before that, we had the discussions of "Standard C" and the #ifdef tricks we used to play to struggle to get one source file to compile on all the different platforms that C runs on.
And that, folks, is the heart of the matter: long before Gosling took his fledgling failed set-top box Oak-named project and looked around for a space to which to apply it next, developers... no, let's get that right, "developers and their managers who hate the idea of violating DRY by having the code in umpteen different codebases" have been looking for ways to have a single source base that runs across all the platforms. We've tried it with portable languages (see C, C++, Java, for starters), portable libraries (in the C++ space see Zinc, zApp, XVT, Tools.h++), portable containers (see EJB, the web browser), and now portable platforms (see PhoneGap/Cordova, Titanium, etc), portable cross-compilers (see MonoTouch/MonoDroid, for recent examples), and I'm sure there will be other efforts along these lines for years and decades to come. It's a noble goal, but the major players in the space to which we are targeting--whether that be operating systems, browsers, mobile platforms, console game devices, or whatever comes next two decades from now--will not allow their systems to be commoditized that easily. Because at the heart of it, that's exactly what these "cross-platform" tools and languages and libraries are trying to do: reduce the underlying "thing" to a commodity that lacks interest or impact.
Interestingly enough, as a side-note, one thing I'm starting to notice is that the more pervasive mobile devices become and the more mobile applications we see reaching those devices, the less and less "device-standard" those interfaces are trying to look even as they try to achieve cross-platform similarities. Consider, for a moment, the Fly Delta app on iPhone: it doesn't really use any of the standard iOS UI metaphors (except for some of the basic ones), largely because they've defined their own look-and-feel across all the platforms they support (iOS and Android, at least so far). Ditto for the CNN and USA Today apps, as well as the ESPN app, and of course just about every game ever written for any of those platforms. So even as Charlie argues:
We are starting to see mobile app developers actually striving to define their own UI model entirely, with only passing nod to the standards of the device on which they're running. Which then makes me wonder if we're going to start to see new portable toolkits that define their own unique UI model on each of these platforms, or will somehow allow developers to define their own UI model on each of these platforms--a UI model toolkit, so to speak. Which would be an interesting development, but one that will eventually run into many of the same problems as the others did.