Bruno Ghisi's Blog

Bruno Ghisi is a Java enthusiast with focus on Java ME, open source and wireless technologies. He is a Mobile & Embedded Community Star and Java Champion. In addition, he helps a JUG called GUJava/SC and maintains some open source projects, such as Marge. He is a new grad that intends to do a Master and currently works for CERTI Foundation. Also, he lives in an island in the south of Brazil called Florianópolis.

Why do we write open source code?

For some time I was thinking about writing this post and I have just watched Chris DiBona presenting a fantastic session called Open Source is Magic in Google I/O and got motivated. In addition to this, today is Download Day (if you have not downloaded Firefox 3.0 yet, go ahead and do it), so nothing better than write about open source on this Tuesday.

I was deep thinking why people write open source code. I am not talking about why companies do it, I am talking about you, as a developer, do it in your free time. According to a very interesting BCG/OSDN Hacker Survey made in 2002 - I could not easily found it, so Chris got me a copy (thanks!) - it could be extracted 4 groups from the different motivations answered by the public: believers (do it because they think open software should be open), professionals (for work needs and professional status), fun seekers (for non-work need and intellectual simulation) and skill enhancers (for skill improvements).

[Updating] The motivations that made the groups:

I can understand this group segmentation, but I think the time has definitely changed and we - communities, companies and softwares - have definitely evolved. Some years ago, Java was not open source, Firefox and OpenOffice.org were getting more adopters, Ubuntu was not out, companies were not doing contests and giving prizes away, etc, etc, etc. But my big question is, why do you write open source code? I mean, why do you join, for example, java.net, SourceForge, Google Code or freshmeat and commit your code there in order to create a whole community around it? Why do you send code to help a current open source project? Answering this question, I would say that I am a believer because I do it for the knowledge sharing between people, but I definitely do it for the fun too. How fun is sharing your ideas, getting new ones, mixing all together and creating something even more nice?! Talking about fun, would you will invite someone to go out for a glass of water on Friday night? Neim! It is the same as wasting your free time to write something that you do not get excited, it just does not make sense.

So, it is your turn. What do you think about the current period that open source is passing? What do you do for open source and why do you do it? Any other comments you may have, please feel free to add!

PS: I was looking some other presentations in Google I/O and there was a slide showing the book Producing Open Source Software from Karl Fogel. I have read this book some time ago and it has a pretty interesting reading if you want to learn about the nature of maintaining an open source project. Take a look!

Cheers,
Bruno Ghisi

Playing with Mobile Sensor API, Marge and JavaFX Script

I am disappointed... I could not go on with my tests envolving phoneME Advanced on iPhone due to iPhone SDK just runs on Mac OS X. Boring week, I bought an iPhone for that and someone thought everybody should have a Mac OS X to use it... what a nice thing! Anyway, let's change plans for now... I found something funnier: let's play with JSR 256 (Mobile Sensor API or MSAPI). But let's use Marge (Bluetooth) and JavaFX Script too!

MSAPI in NetBeans

The current Wireless Toolkit, 2.5.2, does not support MSAPI yet, so you need to make some tricks.

First: Download the JSR 256 RI. If you do not have a Forum Nokia account, go ahead and make one. Unfortunately, it seems the zip is packed for Windows due to the .bat and .exe files inside, but it looks that it is just script files, so probably works on other OS if you adapt.

Second: I suppose you already have NetBeans 6.1 with Mobility Pack, so let's add a new platform into it. Go to Tools->Java Platforms->Add Platform...->Select Java ME MIDP Platform Emulator->Click Next->Select the folder you have extracted the downloaded zip and advance until the end. If everything went well, you probably got a new platform called Prototype 2.0 S60 MIDP Emulator. Great! You are now able to create and compile applications that uses MSAPI specification.

We are not going to emulate the sensors, but if you want, go ahead and start $RI_PATH/tools/simulator/bin/start_sensorSimu.bat.

Starting with MSAPI

From the specification:...it allows Java ME application developers to fetch data easily and uniformly from sensors. A sensor is any measurement data source. Sensors vary from physical sensors such as magnetometers and accelerometers to virtual sensors, which combine and manipulate the data they have received from other kinds of physical sensors. Examples of virtual sensors could include, for example, battery level sensor indicating the remaining charge in a battery, or a field intensity sensor that measures the reception level of the mobile network signal in a mobile phone. The sensor may be connected to the mobile device in different ways, represented by the connection type, examples of which are embedded, short-range wireless, wired, and remote connection type.

The classes and interfaces of this API are defined in the package javax.microedition.sensor.

To start playing with sensors, basically you need to find them in order to get a the SensorInfo references. There are two static methods in SensorManager for that: findSensors passing the sensor url and the overload one passing the quantity and the context of use (if you set null for both parameters, all the supported sensors will be returned). From our demo application:

SensorInfo[] si = SensorManager.findSensors("acceleration",
  SensorInfo.CONTEXT_TYPE_USER);

After that, you can connect into the sensor using the well known Generic Connection Framework (GCF):

String url = si[0].getUrl();
SensorConnection sensor = (SensorConnection) Connector.open(url);

Then, you can start collecting the data. There are two ways of collecting the data in MSAPI: synchronously and asynchronously. In the first, you have to call SensorConnection getData iteratively. In the asynchronous way, you have to register a DataListener, invoking setDataListener and passing a reference of it and a buffer size (this number will be determine the data collecting frequency), that will be responsible for calling the dataReceived method. This method will return the SensorConnection reference, an array containing the data channels (for example, for a 3-axis accelerometer, the array will have length 3) and usually the last parameter will be false when the listener handles the data quickly:

sensor.setDataListener(new DataListener() {
  public void dataReceived(SensorConnection sensor, Data[] data, boolean isDataLost) {
    ...
  }
}, 10);

Our demo: Bluetooth Sensor FX Tetris

The demo of this post is pretty simple. I got the Bluetooth JavaFX Tetris Game and changed the way of interaction. You do not have to type the direction in your mobile anymore, you can now use its accelerometer. Avoid typing, you can get a RSI (Repetitive Strain Injury)! Basically, I have implemented the dataReceived method to process the data collected and send over Bluetooth to the game. It is still missing some better balance in the accelerometer as you can see, but works as a proof of concept.

The code of JavaFX Tetris Game (BluetoothJFXTetris) is under Marge's Demos repository as well as the MIDlet controller (genericbtsensomapper-mobile). Go ahead and checkout them! They are open source! I have tested this demo with my designer friend' Sony Ericsson K850i and worked... as a demo, off course! I have noticed that sometimes the game crashes, I am not sure yet why, but I suspect that is something related to threads and rendering.

Here is a terrible preview video. It was recorded using the phone mentioned in the beginning of the post, probably I will have to record it again, but I could not wait until tomorrow to post about this experiment:

Thanks to Raghavan Srinivas that pushed me up to work on this demo during our fast talk at JavaOne! Cheers!

Have a nice week! :)
Bruno Ghisi

First steps with iPhone and Java...

When I was at JavaOne, I sold my soul to devil: I bought an iPhone. Here in Brazil, there is no iPhone being officially selled yet.

Let's start having fun and playing with Java on it:

1. Unlock your iPhone. Babies can do that before they say mama. More information at Zibri's Blog.
2. Make it useful: Install Cydia (front-end for Debian APT) to substitute default Installer application. In Installer, go to the Source option, click Edit, Add http://apptapp.saurik.com, Done and then Refresh. Then go to Install option, search for Cydia Installer and install it.
3. After that, open Cydia and search for the word Java, there are a few stuff part of the iPhone/Java package available in Development menu. You are able to make graphical applications using the UI Framework, which is possible due to JocStrap, a Java/Objective-C bridge. Install iPhone/Java that will bring the necessary stuff (JamVM, etc) for this simple demo. Also, later try to install Jikes, a compiler for version 1.4 and fastjar, an alternative for running jars, because I could not test them yet.

PS: Install OpenSSH in your iPhone and then connect your laptop on its server. Also, install Boss Prefs to be able turn SSH on/off. Finally, do not forget to change you root password using passwd, default password is alpine.

I have created a simple Hello World app into NetBeans. Then I have compiled it, tranfered to iPhone and runned (via SSH).

Code:

public class Main {

    public static void main(String[] args) {

        System.out.println("Hello World... in Java");

    }

}

Screenshot:

Community will bring ME world into iPhone as well. The answer for this is phoneME Advanced. Keep and eye and join the mailing lists! As you can see, there are some very nice projects going on!

Have a nice and funny week!

Bruno Ghisi

LWUIT is the way!

Forget about what I have said previously, LWUIT (Lightweight UI Toolkit) is the way!

LWUIT was launched at JavaOne 2008 and there are already some nice tutorials and demos about it. I met some of the guys in the Pavillion and I was impressed with the lib, very cool! Another point is that you can also use LWUIT in commercial applications, it was released under the SLA.

LWUIT is a UI library that is bundled together with applications and helps content developers in creating compelling and consistent Java ME applications. LWUIT supports visual components and other UI goodies such as theming, transitions, animation and more.

Don't waist your time drawing Canvas, take a look on it!

Bruno Ghisi

J1 is awesome!

There is no word to describe what is JavaOne. If I take a try, I would say that is definitely awesome! It rocks! It is the best geek tourism ever!!!

The sessions are great, the speakers are great, the Pavillion is great, the communities, companies, people, all the information, flyers, talks, contests, chats, demos, videos, places, souvenirs, stuff, food, parties, pubs, dinners... the coolest people from the whole world speaking about Java and whatever runs in a JVM!

I will not describe all the sessions and things I have seen, because I could easily write a few of books about it. I suppose everyone have seen different JavaOnes, due to the many information in its atmosphere and because we cannot split ourselves in time... So, I have added some pics that show much more. Follow them to see what happened with me, probably not in this sequence, but I can't remember, I spent a whole week as it was a day! Too much fun!

And the fun was just starting...

...do you know that people are the center of everything that happens?

...I mean, because of a lot of people, all those things happens...

...yes, a lot of... and in everywhere, the Pavillion was awesome to meet them...

...and those people play video games when they are tired... or sometimes just rest...

...you can meet those people in a Smash Mouth concert... who does not like rock?

...I met Aaron Houston there... is he Brazilian?!

...he took me to a cool JavaPosse session... very informal and funny, as you can see...

...then I got my car and it drove me ti the next pub...

...yeah... definitely everybody likes rock!

...a lot of Mobile and Embedded people were there!

...Have you seen all the cool demos we got?

...after some pints, I think I was in Mars...

...and then I encourage myself and got a Marge Duke tattoo...

...I can't remember the rest, but I wake up with Neil Young in the stage... wow...

...then I just discovered that Jonh Cage is Brazilian too... he said don't be shy!

...yes... I tried...

...so, James Gosling just appeared in the CommunityCorner...

...and all his fans liked that!!!

...too much things going on... time to rest, let's watch a movie...

...everybody would be tired after a day like that, don't you think, Roger?

As 24Hrs (do you know Jack Bauer?) episode would say, the following take place between 5th of May and 9th of May... something like that, I cannot remember the hours exactly...

Great to meet everybody and be part of this! It was my pleasure! I got addicted to JavaOne!!!

What a busy day!

Thanks,
Bruno Ghisi

Marging a FX Tetris at JavaOne!

Marge (Java Bluetooth Framework) got a mini talk in Community Corner. It will be on Wednesday at 3:30 pm. If are you interested in Bluetooth, JSR 82 (Java Apis for Bluetooth) and Marge, do not miss that! We have integrated a Bluetooth mobile controller for a nice James Weaver's compiled JavaFX Script tetris game! Thanks, Jim!

Here is a preview (updated):

The old video is at http://www.youtube.com/v/ZvVx6RGjCjM

It will be easy to find Marge:

Here is the last tip, keep an eye on the Mobile and Embedded Wiki page for JavaOne!

I am very excited to meet new people! See you in San Francisco!

Bruno Ghisi

Pics from fisl 9.0

The 9th edition of fisl (International Free Software Forum) was huge! 7417 participants from 21 countries talking about open source 12 hours by day during 3 days. Wow! Great atmosphere! Great sessions! Great people! Great ideas, discussions, dinners...

Here are some pics that I got from my terrible camera:

Ale Gomes, from Mobile & Embedded, and Fabiane Nardon, JavaTools Community Leader.

Bruno Souza, Javali, Brazilian Sun Ambassadors, OpenSolaris User Group... did I forgot anyone?

Marge checking out a mobile session with her MSA compliant device!

Lucas Torri, Roger Brinkley and I. Sorry model agencies... no runways, we are busy....

What a nice guy!

Roger Brinkley, Mobile and Embedded Community leader, playing golf during his cool session!

Bluetooth about:

The slides of the session Marge, an open source framework for building Bluetooth applications in Java are available only in pt_BR (pdf and odf). mOOo Impress Controller was used to control the Impress presentation with the mobile and Giant Blue Pong was the demo showed in the end. Thanks for the audience, sorry if we had to hurry up. If you got any doubts, please send an email to us (mailing lists here).

During fisl, we have discovered a very nice thing! Bluecove, a JSR 82 Java SE implementation, is already working over BlueZ, the official Linux Bluetooth protocol stack. There is no release yet, but the snapshots we have tried are stable. Thanks to Vlad Skarzhevskyy, one of the project owners, that virtually helped us to put things working for our demo. Now you can have multiple connections in Linux, something that AvetanaBluetooth (open source) did not allow. Great news! Congrats to the Bluecove team! :)

Thanks,

Bruno Ghisi

Starting with Sun SPOT using NetBeans 6.1

If you do not have a Sun SPOT (Figure 1), do not be bored, you can still have a lot of fun! In this entry, I gonna explain how to start programming the world using NetBeans 6.1!

Figure 1: Sun SPOT rulez!!!

Downloading NetBeans IDE 6.1

Installing Sun SPOT plugin

Getting Sun SPOT SDK 3.0 Beta

Creating the Demo Application

    protected void startApp() throws MIDletStateChangeException {

        System.out.println("Hello, world");

        new BootloaderListener().start();   // monitor the USB (if connected) and recognize commands from host


        long ourAddr = Spot.getInstance().getRadioPolicyManager().getIEEEAddress();

        System.out.println("Our radio address = " + IEEEAddress.toDottedHex(ourAddr));

        ISwitch sw1 = EDemoBoard.getInstance().getSwitches()[EDemoBoard.SW1];

        leds[0].setRGB(100,0,0);                // set color to moderate red

        while (sw1.isOpen()) {                  // done when switch is pressed

            leds[0].setOn();                    // Blink LED

            Utils.sleep(250);                   // wait 1/4 seconds

            leds[0].setOff();

            Utils.sleep(1000);                  // wait 1 second

        }

        notifyDestroyed();                      // cause the MIDlet to exit

    }

Running the Demo Application in the emulator

Where I go next?

Building a Java ME Bluetooth chat in 12 minutes...

As it was announced before, Marge 0.5 is out. In this post, I am going to demonstrate an interesting new feature called AutoConnect. AutoConnect is indeed to automatically connect Bluetooth devices. It has some limitations due to some bad implementations and has some scenarios that maybe it is not the best option, but still very interesting and is definitely awesome to make something with a few lines of code! For more information about the new release and this feature, please check http://wiki.java.net/bin/view/Mobileandembedded/HowTo05.

So, nothing better than show a video... [sometimes I think I should have done cinema :) ]... Anyway, if you have not seen any Marge videos yet, try "Project Marge Interview", "My laptop is detecting my presence" and "Giant Blue Pong (my Bluetooth Atari)". Too much talk, take a look at the new "Building a Java ME Bluetooth chat in 12 minutes..." too. Could you not understand what happened in Netbeans code editor? Neither do I!!! It is better to download the full video (30MB). Hope you enjoy!

If you want more about Marge, go to http://marge.dev.java.net. If you want to help, please send an email to owner@marge.dev.java.net. We would love to hear suggestions and have you in our team!

Go ahead! Marge your Bluetooth app!

June 2008

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Why do we write open source code?

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