Thursday Jan 30, 2014

Internet of Things (IoT) Hackathon in Brazil

SouJava is running a Raspberry Pi and Java hackathon at Campus Party, the week-long technology gathering of geeks, developers, gamers, scientists, and students in Brazil. Sponsored by Oracle Technology Network, the hackathon is designed for enthusiasts who want to create IoT projects with Raspberry Pi and Java. The objectives are for attendees to learn, practice, and innovative while creating an IoT project

Java evangelist Angela Caicedo opened the hackathon with an overview of IoT and Java development. Over two days, participants will build teams, brainstorm, attend training, get a kit from the organizers and hack on their own project. Onsite experts will be available to help participants. They are veteran Java developers of web, enterprise and embedded development. Among them are GlobalCode founder Vinicius Senger, senior developer Rubens Saraiva, SouJava leader Bruno Souza, Java Champion Yara Senger, product manager Bruno Borges and senior mobile developer Ricardo Ogliari 

Learn more about IoT:  
- IoT community page highlighting projects, discussions, hobbyists, and experts

Wednesday Jan 29, 2014

Gamification for User Groups

At the gamification session of the International Oracle User Group Community (IOUC), leaders discussed how to drive membership. Typically, they give away licenses, books and goodies to encourage attendance at monthly meetings. Others have used gamification to get their communities to brainstorm on mascot names, or post pictures and comments on social media. Hackathons also require the use of similar techniques to keep attendees motivated to create applications over several days. SouJava leader Bruno Souza successfully ran hackathons that combined brainstorming, team building, training, hacking sessions and prizes to keep participants engaged.

“Turn life into a game, drive engagement of audiences, make the experience more enjoyable and get users to come back ” are the key advantages of gamification according to user group leader Jim Bethancourt.

The forum platform Stack Overflow is a great example of running a thriving community of developers with its point systems. Contributors get rewarded with points for their useful entries and visitors easily find the most relevant and best-rated entries.

The ArabOUG has implemented a point system to keep its community active. The group gives out points to the members, who contribute applications, articles, and translations. It partnered with training organizations and other services to give its members free training and services in exchange for points. As a result, members don’t have to pay for services using online payments, which governments in many countries in North Africa and the Middle East don’t allow.

In an interview, ArabOUG leader Mohamed Chargui  explains in more detail his experience using gamification.

Wednesday Dec 11, 2013

Devoxx 4 Kids with the NAO Robot

Software Architect Daniel De Luca discusses Devoxx 4 Kids, a program to introduce children to software programming. "We want to teach children to be creative with computers and build games in an easy way instead of just using technology" explained Daniel De Luca. "The NAO robot is another computer with multiple sensors on their feet and hands, a sonar, and more." The events are currently planned in over 10 countries. The training resources are freely available on Devoxx4Kids. Daniel with other event organizers presented the Devoxx 4 Kids best practices session with tips and tricks to organize such events.

Thursday Nov 28, 2013

Java Mission Control - Production Time Profiling Out of the Box

By Guest blogger: Marcus Hirt

With the release of 7u40, there is a new kid on the JDK tooling block – Java Mission Control. This article will try to explain why it is worthwhile to take a closer look at this technology, as well as provide pointers on how to get started. 


Mission Control is a production time profiling and diagnostics tools suite that originated with the tooling available for the JRockit JVM. 

As part of the development effort of the JRockit JVM we started building tooling for analyzing the runtime performance of the JVM. We needed information about how real production systems were utilizing JRockit. Requests to get customers to lend us their latest top secret trading applications for evaluation in-house were usually, quite understandably, met with telling blank stares calling our sanity into question. It probably wouldn’t have done us much good anyways, since we wanted production data from systems under real loads. Thus we built a tool (the JRockit Runtime Analyzer, which later evolved into the JRockit Flight Recorder) with low enough overhead that we could convince customers to actually use it to collect production time data for us.

Eventually we accidentally solved some customer problems using the tools and customers started asking us if they could license them. The idea was born to spend some more resources on the tooling and make it a commercial tool to pay for its development. JRockit Mission Control was born.

Java Mission Control

After Oracle acquired Sun Microsystems, Oracle suddenly had two of the top three most commonly used general purpose JVMs available on the market. One was the open sourced reference JVM, with a lot of people knowing the source and licensees basing their own ports and versions of JVM off of it. The other JVM, whilst being a quick and pretty little thing, was proprietary with a rather small number of people knowing the code base. Instead of having to support two JVMs, Oracle wanted to pool the available resources into building a best of breed JVM. It was decided that the base would be HotSpot and that the most useful features in JRockit would be ported over – one of them being Mission Control.

In JDK 7u40 the functionality available in HotSpot had reached critical mass, and the very first version of Java Mission Control (unfortunately versioned 5.2.0) was released. It mainly contains equivalents of two of the JRockit Mission Control tools – the JMX Console and the Flight Recorder. There is no on-line heap analyzer yet. There is however a set of quite useful (experimental) plug-ins for JMC, extending Mission Control to do heap dump analysis, targeted analysis for various oracle products or simply extending existing functionality in more (or sometimes less – yes, I’m looking at you Twitter Trigger Action) useful ways .

Getting Started

Starting Java Mission Control is quite easy. Download a recent enough Java 7 JDK (7u40 or later), then simply launch %JDK_HOME%/bin/jmc. The alien thing that now starts is not, as I am sometimes asked, a native application. It’s Java, but it’s built upon Eclipse RCP technology. If you would rather run JMC inside of Eclipse, you can install JMC into your Eclipse from the JMC update site. A word of caution here – because of a bug in Eclipse/SWT, Mission Control performance is horrible in Eclipse 4.x. This bug is slated to be be fixed in Eclipse 4.4, but until then I strongly recommend either using the stand-alone version of JMC, or installing it into an Eclipse 3.8.2. 

The JMX Console

The console in Mission Control can be thought of as a JConsole on steroids. It allows you to monitor JMX data in various ways, to take action when attributes attain certain values and to persist the data and later look at what has been recorded. There are various experimental plug-ins for the console, such as a Coherence plug-in, a plug-in for running JConsole plug-ins and a plug-in for tweeting messages when a action triggers. 

To connect the console to a JVM, simply choose the JVM you want to connect to in the browser tree and select Start JMX Console. If the JVM was started locally or with JDP, then it will automatically appear in the JVM browser. If you have a remote JVM without JDP running, just enable the built in JMXRMI agent as you normally would to be able to connect with JMX clients such as JConsole.

The JMX console is typically used to monitor a small set of critical attributes, such as the CPU load and Java Heap usage, sampled at a relatively low frequency. The console can be configured to take action when undesirable values are reached for an attribute, and one of those actions can be to dump Flight Recorder data. The JMX console also contains special tabs for looking at thread information, such as deadlocked threads, per thread allocation information and per thread profiling information. That said, the JMX console is used for monitoring the runtime. When profiling capabilities or better diagnostic information is needed, the one stop shop is really the Flight Recorder.

The Java Flight Recorder

The Java Flight Recorder can be thought of as of the equivalent to the Data Flight Recorder for an airplane, but for the Java runtime. While it is running It records information about the JVM and its environment. When something “interesting” happens, the data in the Flight Recorder can be dumped, and the information analyzed off-line to gain an understanding of why everything suddenly went from good to “interesting”. Having the Flight Recorder running as an almost unnoticeable impact on the performance of the Java Application running in the JVM. The overhead is usually well below a per cent. This is achieved by having a high performance recording engine built directly into the runtime and collecting data already being tracked by the runtime or as part of an activity where the data is reachable. (As opposed to actively having to do additional work to get the data.) There are a lot of interesting things that can be said about the recording engine implementation, but this being an overview article, I’ll just move on to how to use it, not how it does what it does.

Creating Flight Recordings

The most important difference to how the Flight Recorder worked in JRockit is that in HotSpot two JVM start-up flags must be enabled on the JVM for which you want to do flight recordings:

-XX:+UnlockCommercialFeatures -XX:+FlightRecorder

And that was probably the most important line in this article. 

There are two different types of recordings, and you can have multiple recordings (of different types) running simultaneously:

1. Timed recordings 

These recording run for a pre-configured duration. They are automatically stopped when the time is up. If initiated from JMC, they will be automatically downloaded and opened in the user interface when done. 

2. Continuous recordings 

These recordings have no explicit end time and must be dumped by the end user. 

Now there are three different ways you can do actual recordings, once the parameters are in place:

1. From Mission Control. This is probably the easiest way. Just point and click. 

2. From jcmd. This is a very useful way to control the Flight Recorder from the command line. Quite useful when you can’t access the machine that is running the JVM of interest from Mission Control and you only have access to a shell. 

3. Using command line flags. This is handy when you want to always run with a continuous recording, or when you want to record the start up behaviour of the JVM right from the very start. 

If you want to know more about how to create Flight Recordings, this blog entry is probably a good place to start. 

Analyzing Flight Recordings

There is a lot of useful information in the flight recordings, and there are a lot of different things the information can be used for. For example:

Method profiling. The Flight Recorder will quite happily do method profiling in production systems with a very low overhead. As a matter of fact, it’s even enabled in the continuous template, so go ahead and use it. It will tell you where the hotspots are in your application. In other words, if you have a CPU bound problem, the method profiling information will tell you where to optimize to get things to go faster. 

GC profiling. The GC implementations emit useful events at GC related activity. Information that can be used to check on the live set, semi-refs, GC pauses (and their individual sub-phases) etc. Quite useful for GC tuning, finding out if you’re overusing finalizers and more. 

Allocation profiling. If you do notice a lot of garbage collections, but don’t notice anything strange about the individual GC phases, you may want to kick back a bit on the allocation. Allocation profiling will help you see where all that allocation activity is putting it’s toll on the memory system. 

WebLogic Server analysis. WebLogic is producing its own set of events for the Flight Recorder. They are quite useful in their own right, but can also be good for putting all the other information recorded in a context - “What was really happening during this transaction?”. This article on the Operative Set shows some of the capabilities. 

Latency Profiling. The Flight Recorder has a lot of different events for various thread stalling activities that can occur, such as blocking on monitor enter, parking, waiting etc. I can’t believe I haven’t written a blog post on this yet. Shame on me. This is usually the first place to look if you haven’t got a CPU bound problem, but still performance issues. 

OS information. CPU load, JVM CPU load, environment variables, running processes – there is a lot of operating system information. If you still can’t find what you’re looking for, Mission Control has a D-Trace plug-in for retrieving everything you ever wanted to know, but were too afraid to ask. Note that the overhead from using D-Trace, even with very few probes, is usually more than an order of magnitude worse than just using the Flight Recorder – use with caution. 

There is much more information available from the event providers built into the JVM, such as class loading and compiler events. One way to learn more details about what is available is to take a closer look at the metadata from a recording.


Since JDK 7u40 there is a new tools suite bundled with the JDK – Java Mission Control. The main focus of the suite is on production time profiling and diagnostics. This has the benefit that the data gathered is quite true to the dynamics of the application being profiled, as the observer effect is kept quite low. In other words, instead of profiling the profiler itself, most of the time is actually spent profiling the application and the runtime. Whilst the main focus of Mission Control is production systems, it can be quite useful in development too. It is also free for use in development, as per the standard Oracle Binary Code License (BCL).

This article provided a brief introduction to Java Mission Control.

Further Information

Java Mission Control Homepage

My Blog

@javamissionctrl;  @hirt

Monday Nov 11, 2013

Hack Fest Going Strong!

Today was the first day of  the IoT Hack Fest at Devoxx, the Java developer conference in Belgium.  The IoT Hack Fest started with the Raspberry Pi & Leap Motion hands-on lab. Vinicius Senger introduced the Java Embedded, Arduino and Raspberry Pi. Java Champion and ZeroTurnaround Geert Bevin presented the Leap Motion, a controller sensing your hands and fingers to play games by controlling the mouse for example. "Programmers are cooler than musicians because they can create an entire universe using all senses" explained Geert

Participants started building applications in teams using Raspberry Pi, sensors and relays. One team tested the performance of Tomcat, Java EE and Java Embedded Suite on the Raspberry Pi. Another used built an text animation using a LCD screen. Some teams are using the Leap Motion to close and open programs on the desktop and others are using it as a game control. 

Tuesday Sep 24, 2013

The Eleventh Annual Java Community Process Program Awards

by Timothy Beneke and Janice J. Heiss

In a festive room teeming with over 200 people, including many celebrated Java luminaries,
along with excellent food and drink, the 9th annual JCP Program Awards were handed out atop the majestic Hilton Hotel on Monday night. As the JCP states, “The Java Community Process (JCP) program celebrates success. Members of the community nominate worthy participants, Spec Leads, and Java Specification Requests (JSRs) in order to cheer on the hard work and creativity that produces ground-breaking results for the community and industry in the Java Standard Edition (SE), Java Enterprise Edition (EE), or Java Micro Edition (ME) platforms.”

The JCP added a new awards category this year for Adopt-a-JSR program participants, bringing the total to four: JCP Member/Participant of the Year, Outstanding Spec Lead, Most Significant JSR, and Outstanding Adopt-a-JSR Participant.

The room was full of good cheer, playful humor, a music band of Java developers, and enthusiastic appreciation of much that has been accomplished on behalf of Java technology in the previous year.

The nominees and winners in their respective categories were:

JCP Member/Participant of the Year

--Azul Systems, Gil Tene

--London Java Community (LJC), Ben Evans, Martijn Verburg, Richard Warburton, Graham Allan

--Mohamed Taman

The winner was Azul System’s Gil Tene. The JCP said, “Gil has worked diligently to provide clear advice on matters of Software Patents, IP and licensing that seeks to benefit both non-profits/individuals etc as well as organizations with vested commercial interests in Java. It's not easy delving into the depths of the legal aspects and the potential impacts of changes to the JCP, but with help from folks like Gil we're hopeful for a solid and fair outcome.”

Tene characterized his approach to the JCP as follows: “I represent Azul Systems on the JCP EC, but I try to apply an approach of ‘do the right thing first’ in my choices and positions. Coming from a small company that depends on Java and its ecosystem for its livelihood, I see my role as representing the interests of an entire sector of non-big-company commercial folks and of individual and professional developers out there, and providing some offset and balance to the normal mix of such boards.”

Outstanding Spec Lead

--Brian Goetz, Oracle

--Jitendra Kotamraju, Oracle

--Anatole Tresch, Credit Suisse

--Chris Vignola, IBM

The winner, Oracle’s Brian Goetz, was recognized, “For tirelessly working away at an incredibly complex JSR - JSR 335, Lambda Expressions for the Java Programming Language. From a community point of view, we've appreciated his willingness to listen and consider ideas from other technologists as well as spending time with groups of developers to understand the impact of Lambdas on Java.”

Goetz offered a statement in response to the award for his leadership in creating Lambda Expressions for the Java Language, which also won for most significant JSR. He said that lambdas, “represent a coordinated co-evolution of the Java SE platform, including the VM, language, and core libraries to provide developers with a powerful upgrade -- quite likely the largest ever -- to the Java SE programming model. We started this JSR in early 2010, but the topic of closures-in-Java had already been in play in the community for many years prior, and, of course, there was a broad diversity of opinions as to what direction, how far, and how fast to evolve the Java programming model. In the end, the most significant dimension of the challenge turned out to be: how do we integrate these new features in the language and libraries without them feeling grafted on after-the-fact. I think developers will find programming with this ‘new and improved Java’ to be a very pleasant experience -- I know I have.”

Most Significant JSR

--JSR 335, Lambda Expressions for the Java Programming Language

--JSR 344, JavaServer Faces (JSF) 2.2

--JSR 352, Batch Applications for the Java Platform

--JSR 354, Money and Currency API

--JSR 355, JCP Executive Committee Merge

The winner, as previously mentioned, was JSR 335, Lambda Expressions for the Java Programming Language, which the JCP praised as follows:

“This brings Java kicking and screaming into the modern programming language age and is seen as a catalyst for the second age of Java. It's underlying discoveries and improvements with regards to Type Inference has also resulted in a stronger JVM for all.”

Spec lead Brian Goetz, in picking up the award, remarked, “This is something we’ve been working on for three-and-a-half-years and it’s nice to be looking at it through the rear-view mirror.”

Outstanding Adopt-a-JSR Participant

--BeJUG, Johan Vos

--CeJUG, Helio Frota, Hildeberto Mendonça

--JUG Chennai, Rajmahendra (Raj) Hegde

--Morocco JUG and EGJUG, Mohamed Taman, Faissal Boutaounte

The winner was Morocco JUG and EGJUG, Mohamed Taman, and Faissal Boutaounte, who were praised, “For adopting JSR 339, JAX-RS 2.0 specification, along with many other JSRs. One JIRA issue filed by Morocco JUG on JSR 339 was classified as a ‘release-stopper’. A quick JIRA search using the ‘adoptajsr’ tag shows that most of the JIRA issues have been created by MoroccoJUG members. Several presentations and source code have been organized by these groups. Mohamed presented sessions about the upcoming technologies to widen the range of users in the future, especially Java EE 7 JSRs and spreading of community progress and contributions that make us encouraged to participate. Mohamed sent a clear message that Africa is here and is full of talented people who are willing to take it to the next level. Mohamed was responsible for translating an Arabic Adopt-s-JSR web page to allow more Arabs to participate.”

Taman said that, “Currently, I hold two positions, one as a Business Solutions Systems Architect and design supervisor and Java Team leader, at a big financial services company in Egypt, which affects all the country by building solutions affecting Egyptians every day, by providing more facilities for businesses and enhancing the economy… I am passionate about Java. I really love it and have fun coding, and love seeing it grow, day by day, as if it were my kid.”

The Annual Java Community Process Program Awards at  JavaOne is an event and party not to be missed!

The Java Community Process

Thursday Jun 06, 2013

A Java EE 7 Sneak Peek!

Next week, Wednesday the 12th, Oracle executives and technical experts will present the ins and outs of Java EE 7 in a live webcast

In this presentation, technical expert Arun Gupta gives a preview of the new and updated JSRs in Java EE 7. He also lays out the plans for Java EE 8. 

Join us for the live webcast: Introducing Java EE 7 on June 12th, 2013. It is free! 

Thursday Apr 04, 2013

Golo – A Lightweight Dynamic Language for the JVM

Julien Ponge, who, in addition to being a Java developer and a professor, also writes technical articles for both otn/java and Java Magazine, has created Golo, a simple, dynamic, weakly-typed open source language that favors the explicit over the implicit. Developers can pick it up in a manner of hours, not days. Responses to its recent release at Devoxx have been favorable.

Built from day 1 with invokedynamic, and currently in beta, Golo takes advantage of the latest advances of the JVM. It is also a showcase on how to build a language runtime with invokedynamic.

The Golo Programming Guide is located here.

Julien is an Associate Professor (Maître de Conférences) in Computer Science and Engineering at INSA-Lyon in France, plus an R&D Computer Scientist at the CITI / INRIA laboratory. Learn more about him here.

Thursday Mar 07, 2013

OpenJDK Test Fest and Devoxx UK

The London Java user group is organizing the first Test Fest on March 23rd in London with the collaboration of Oracle and IBM. "Contributors to OpenJDK need to be confident that their changes are sound and do not cause problems elsewhere." explains event host Martijn Verburg. Many test cases are already available but each application has different characteristics, environment and other attributes. The goal is to provide a larger and more comprehensive series of tests for Open JDK. 

If you cannot attend this event, the organizers and some of the guest presenters from Oracle and IBM - among them Oracle engineer Stuart Marks - will be at Devoxx UK starting Monday evening until Thursday (from March 25th until the 27th). Stuart Marks will present a Bird-of-a-Feather (BoF) session about "the testing of OpenJDK" on Tuesday, March 26th at 8:00pm and Martijn Verburg will talk about OpenJDK Hack Session Tuesday evening at 8:00pm and 9:00pm. Don't forget to register for Devoxx UK!

Additional online resources: Collaborate with the OpenJDK Quality team Online information FAQ

Wednesday Mar 06, 2013

Get started with Java!

Every year, the Java platform is growing with new features for enterprise, web, embedded and mobile application and developers. To help beginners navigate the platform and get started with Java technologies, new learning resources are available on the New to Java website. Developers will write a "Hello World" application, test their Java knowledge,  create user interfaces with JavaFX, and build enterprise applications with Java EE, desktop applications with Java SE or applications for mobile and embedded devices.  

Being up to date about current trends and networking with other developers are also critical for a career in programming. Developers can connect with top leaders in the community at conferences and community networks such as local user groups. They have the chance to contribute to open-source projects such as OpenJDK and Adopt-a-JSR to name just two.

Finally, parents and educators teaching programming to children will find software tools for young developers. They are free downloadable development tools with easy to use interfaces for young students. And Minecraft is so popular! Java technologist Daniel Green walks us through Minecraft mods with Java.

Insider News from the Java Team at Oracle!

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