Minggu, 25 Maret 2012

Everything you wanted to know about HTML5 in the car, Part III

Welcome to the third installment in my Q&A series on HTML5 in the car. In Part II, we looked at web servers, native plug-ins, instrument clusters, and display updates. This week, we turn our attention to tools, touch gestures, UI performance, and vehicle resources.

Are there any HTML5 HMI builder tools available?
Most of the well-known IDEs, including Eclipse, Dreamweaver, and Netbeans, support some flavor of HTML5 in their latest release. Adobe Edge, a new tool now available in preview, also lets you create animated HTML5 content. I suggest you check out the HTML5 Tools site, which publishes up-to-date tool reviews.

Often, automotive customers will ask system designers to make an infotainment system work "like an iPhone,” with the popular gesture controls. Does HTML5 support "inertial" menus and two-finger zoom?
Multi-touch is handled at the app level; here’s an example. Pinch zooming at the browser level is browser-dependent — the QNX browser handles it, but not every browser does. As for physics-based scrolling, HTML5 doesn’t support it “out of the box”; it needs to be added. Frameworks like Sencha Touch provide these types of controls.

Will the performance of HTML and JavaScript be adequate for critical user interface components or computations, such as safety-related notifications?
This has to be tested on a case-by-case basis. For the UI elements, yes, the performance should be adequate. Our testing indicates you can build HMIs that are surprisingly responsive. Also, our WebKit port lets you do things things like run JavaScript code in other tabs, threads, or processes to ensure those ocmponents aren’t being thread-blocked by something less critical.

I do get a little gun-shy recommending HTML5 for safety-critical components, because JavaScript isn't inherently real-time. If you wouldn't feel comfortable using Java for a critical coding task, you shouldn't use HTML5 either. If you want predictable, real-time performance for a lower-level computation that cannot tolerate any delay, the code should execute in a non virtual-machine environment. Most code doesn’t really fit that description, so most of the time JavaScript should work just fine.

How do you call vehicle resources — vehicle HMI, vehicle diagnostics information, etc. — on a HTML web app in the car? What's the process in plain words?
In plain words, it’s kinda hard. :-) But here’s my best take on this question: we solve this by creating a vehicle-bus driver that exports data through a publish/subscribe mechanism. The HTML5 layer talks to that piece through a JavaScript interface.

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