Topics in this issue:

• Open source cross platform SDK for mobile devices - including Apple's iPad!
• Debugging a hanged Java app with "kill -3" in Linux
• Flex 4 is out of beta!
• Crazy “comma-first” JavaScript style
• Upcoming courses for software developers

Open source cross platform SDK for mobile devices - including Apple's iPad!

There are now two huge application markets growing very fast - Apple iPhone and Google Android. Still thinking which platform you should choose? Don't worry about it because Appcelerator has just released 1.1.1 version of Titanium SDK which is open sourced and free to use. It could help you build your app with one code and both platforms. Titanium mobile version supports both iPhone and Android, even though the coming hottest mobile tablet - Apple iPad.

Basically Titanium is built on top of the web technologies - HTML5, JavaScript and CSS. Titanium provides its API which plays as a bridge between the application and the OS. You could access Database(SQLite) or File system in those HTML files which you cannot do in normal JavaScript running in sandbox inside the browsers. HTML is used to build the application interface. Here are some highlight features provided by the APIs:

• Touch screen input, gesture and accelerometer
• Media playback
• Facebook integration
• Mobile phone contacts
• Map and Geo-location
• SQLite and file system access

You might think it is again a kind of "write once run anywhere" cross-platform framework. Actually, Titanium have two versions: Desktop and Mobile. Instead of offering a dream of "write once run anywhere", Titanium is more like you could have shared code and logic among different kind of devices like PC/Mac and mobile phone/tablet devices. Nowadays, there are more and more applications running on cloud -- that means those web-based applications are really potential to offer more advanced solutions to deliver experiences across the devices using shared code and interface, services, and APIs.

You could give it a try that if you are a experienced developer and you are familiar with JavaScript and HTML. Because Titanium SDK only provide build and packaging tools and there is no fancy debug or development IDE. You might use your own favorite HTML editor to do the coding and Titanium SDK will build the native executable for you target platform. The good part is that it seems to be integrated with Android/iPhone SDK very well so you could launch your code in the simulator to test your app.

UPDATE: Apple released an updated SDK for the upcoming iPhone 4.0 OS, it forbids developers from accessing Apple's APIs through any sort of intermediary layer that translates code not officially supported by the platform. Executable generated by Titanium might be banned from iPhone OS 4.0 or above.

Debugging a hanged Java app with "kill -3" in Linux

Recently I found Tomcat hanged at startup and just couldn't start it up properly. What to do then? There is a very simple way to find out what a Java application is doing (on Linux platform). First you have to find the pid of Tomcat's JVM process:

The second column of the output is the pid of Tomcat's JVM process.

"kill" command actually is used to send a signal to a process. The second parameter switch is the signal. "kill -3" actually lets JVM know you want it to print the stack trace for you. The stack trace output could be very usually to debug a remote Java app. In my case mentioned above, from the stack trace I found one of the web app was waiting for the response of a SQL statement. It was Hibernate trying to update schema when there are other connections to the database. So it kept waiting.

Whenever you wonder what an app is running, you can do it to find its stack trace. How cool it is!

Ref: http://java.sun.com/developer/technicalArticles/Programming/Stacktrace/index.html

Flex 4 is out of beta!

Flex 4 is finally out of beta. Flex 4 SDK is available for all platforms and Flash Builder 4 (formerly Flex Builder) is currently only supported on Windows and Mac OS X. The Flex SDK open source and free to download. You could download the trial version of the Flash builder 4 or you could purchase for the Premium Edition.

Flex 4 SDK focus on improving the new components architecture (Spark), which has better way to customize stylish and skinning creation. In Spark, you will see that the component function and its looks and feel are separated so the component logic is divorced from component visuals that you could customize a component in a straightforward manner. It just like you customize a submit button in HTML using CSS file. There is a similar skin file introduced in Flex 4 which contains only styles and appearing makeup using FXG. In the old days, you have to do coding to custom to do so. If you want to know more, you could check out this 15-minute-long video here: http://labs.adobe.com/technologies/flash/videos/flashcamp/subra_ruehle/ . The video shows how to make a skin file without coding a line of ActionScript.

For the Flash Builder 4, we could see lots of improvement and they are listed in Andrew Shorten's post (What's new in Flash Builder 4). One thing is very interesting is that Flash Builder 4 supports Adobe Flash Catalyst. Since developing a RIA project, the interface design is very important part. Flash Catalyst brings wire framing which is kind of rapid prototyping a RIA interface without putting too much visual detail at the first time. So developer could do some exploring and demo to customer before getting designer to work on the visual design.  The tool is claimed that you could prototype an interactive interface without writing code. After prototyping, designer could work on the graphic design and finally developer could import the Flash crystal project into Flash Builder. This proposes a better work flow for RIA development. Check out 10-minute-long video about wire framing: http://tv.adobe.com/watch/adc-presents/wire-framing-in-flash-catalyst .

As we could see Adobe try to emphasize their "Flash powered" platform by renaming the product name. Flash player penetration has reached above 95% of Internet-enabled desktop PC. If you are targeted to deliver your application on different platforms as wide as possible, Flex definitely a good choice to invest on. CPTTM will open a Flex course in mid-April , check out here: Rich Internet Application(RIA) development with Flex 3 . Flex 4 is backward-compatible so the course could help you have a good start on Flex.

Crazy “comma-first” JavaScript style

In normal coding style, we usually will put a comma at the end of a line. This is how we usually declare variables in multiple lines in JavaScript: 

So why they are suggesting this? I didn't notice any good at the glance and it looks a little odd to me. But eventually I found that the errors are popped in this style:

See?  In line 3, variable c is missing a conman after it, the error is quit easy to see in comma-first style. Debugging JavaScript is hard since there is no mature IDE for you. You don't need to compile the source, so you might hard to find the missing comma among the lines. You could find more examples about comma-first style here: http://gist.github.com/357981. 

Another advantage is that if you put your codes in source control, you now only have to add lines instead of modifying them:

If you always encounter this, just give this a try. I believe this could also apply to some dynamic languages such as PHP.

Upcoming courses for software developers

Feedbacks