PhoneGap: BlackBerry

Java, J2ME, RIM's browser implementation

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Web & Mobile Development

Nitobi

Overview of the SDKs and PhoneGap support

Many versions...
Before 4.6.1. Lack of 'experimental' rendering in the browser (more on this later). PhoneGap? Nope.
4.6.1. The minimum version of the SDK that we can support. Yes!
4.7 aka Storm. We're good.
5.0 and beyond... Things are looking good, but we still need to implement. SDK currently in beta.
The SDKs boil down to J2ME plus a proprietary library developed by RIM -> not open-source. Sadface.

(Rough) Overview of the BlackBerry Market

Fragmented.

4.2 and below: about 30%; All models up to the early Pearl (BlackBerry 8230)
4.2 to 4.6.1: about 30%; Later Pearl models up to the Bold (BlackBerry 8230 to 9000)
4.6.1, 4.7 and up: about 30%; Recent models like the Bold, the Storm and the Tour.

PhoneGap applications can realistically target 40-50% of all Blackberry devices right now; this number can only grow in the future.

What Can We Do On A BlackBerry?

PhoneGap API, pretty much everything the iPhone can... except:

Accelerometer. SDK access came recently (Storm, Storm 2 and Tour are only models that have accelerometer at this time)

Browser is limited. No XUI, limited DOM implementation and primitive JavaScript error handling. More on this in a bit.

Standards: We've seen this problem before

For PhoneGap to achieve its goal, it needs to have a consistent API across platforms.

BlackBerry Browser Implementation

Support for 'experimental' rendering necessary. Only available for recent SDKs, main reason for exclusion of old models. This came up on StackOverflow...

A lot of JavaScript and the DOM implementation, which is mostly standards-compliant, works in the BlackBerry browser application, but is NOT available in the Field aka Web View.

DOM Level 2 only.

Certain events not supported; i.e. onchange
For changes between level 3 and level 2, check out the W3C spec: http://www.w3.org/TR/DOM-Level-3-Core/changes.html

CSS Level 2 only.
XHR does NOT work. It's ok though. We've implemented our own in Java and added an interface to it via JavaScript.

Device & Browser Nuances

We've said this before: simulator != device

NJust on the Bold 9000 model:

Onkeyup event is not recognized but in the simulator it works.
setInterval basically works like setTimeout - probably because the browser's JavaScript doesn't have reliable timing.
One issue came up after the first on-device deployment with rendering. Details and solution on my blog.

The Browser has two rendering modes. Column View:

Native resolution of most BlackBerries is 480x320 or 480x360. Storm is the exception as it is 360x480.
Column View 'tricks' the browser into thinking the screen resolution is 1024x768, then scales everything down to match the native resolution of the particular device.
Column View will also wrap any content.
Obviously, pixel perfect is extremely difficult.

...and Page View. Page View is better. Simply add: <meta name="HandheldFriendly" content="True" /> to the <head> of your PhoneGap page to trigger Page View.

PhoneGap BlackBerry Architecture / Design

Follows Command pattern - device functionality encapsulated in commands: TelephonyCommand, GeoLocationCommand, MediaCommand, etc.

Message passing done via cookies. We can capture both setting and getting a cookie in the browser from the native end.

PhoneGap Resource Handling

PhoneGap BlackBerry works by instantiating a mini Java browser and feeding it content to display.
We can only feed it HttpConnection objects, so we have to use Java's magical Connector.open function to create these objects.
We trick the connector to open an HTTP connection to a resource on the device by feeding it a Base64-encoded data URI of the local resource.
Can take a while to do this in-real-life-on-the-device, even with caching. For performance reasons, best to keep your entire application on one page.

PhoneGap Architecture Code

public interface Command {

String execute(String instruction);
boolean accept(String instruction);

}

public String processInstruction(String instruction) {

for (int index = 0; index < commands.length; index++) {

Command command = (Command) commands[index];
if (command.accept(instruction)){

try{

return command.execute(instruction);

} catch(Exception e) { }

}

}
return null;

}

Development Experience

The good: object statistics and memory profiler.

Garbage collection! Win, right? Well, maybe not: profiler tells a different story.

Object handles and memory aren't cleaned up properly, even if you explicitly call the garbage collector with System.gc()
You need to explicitly set objects to null once you are done with them to keep your memory footprint acceptable. Does this even count as Garbage Collection? ... Not really.

Still Need More Testing

We haven't tested the entire DOM and JavaScript implementation.
We have developed and tested a few applications, but only on one device for now: The BlackBerry Bold.
Open-Source project - shameless plug. Want to help? Fork the repo from GitHub!

The Future Looks Good

RIM JDE 5.0 (currently beta) seems to be a significant improvement over previous SDKs.

Browser implementation to get better

DOM and CSS level 3!

Widget SDK is another avenue, but it turns out there are no sensor APIs available (i.e. accelerometer, vibration)

Useful Developer Resources

The RIM documentation... but where is it?
Bluntly: their site is useless. Use Google:

'blackberry browser documentation'

The supported HTML, JavaScript and CSS for each SDK version of the browser.

'blackberry api documentation'

The BlackBerry Developer forums are extremely informative.

BlackBerry Application Deployment

App World - Administrative fun to get on here

Apply for signature keys ($$)
Apply as a Vendor ($$ & time)
Submit an application for approval ($20 a submission)
RIM QA team outsources the testing (10 business day turn around time).

Over-the-air deployment.

A common distribution method for a lot of mainstream BlackBerry applications like Evernote, Facebook.
Host the compiled binary (.jar or .cod files) on a web server and serve the files up with a specific MIME type (application/java-archive jar, application/vnd.rim.cod cod).
Direct downloads then possible straight from the device.