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  • Python productivity VS Java Productivity

    - by toc777
    Over on SO I came across a question regarding which platform, Java or Python is best for developing on Google AppEngine. Many people were boasting of the increased productivity gained from using Python over Java. One thing I would say about the Python vs Java productivity argument, is Java has excellent IDE's to speed up development where as Python is really lacking in this area because of its dynamic nature. So even though I prefer to use Python as a language, I don't believe it gives quite the productivity boost compared to Java especially when using a new framework. Obviously if it were Java vs Python and the only editor you could use was VIM then Python would give you a huge productivity boost but when IDE's are brought into the equation its not as clear cut. I think Java's merits are often solely evaluated on a language level and often on out dated assumptions but Java has many benefits external to the language itself, e.g the JVM (often criticized but offers huge potential), excellent IDE's and tools, huge numbers of third party libraries, platforms etc.. Question, Does Python/related dynamic languages really give the huge productivity boosts often talked about? (with consideration given to using new frameworks and working with medium to large applications).

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  • Problem installing the latest eclipse IDE

    - by James
    I'm running ubuntu 11.04. I'm trying to install the latest "eclipse for java developers" IDE (version Indigo 3.7.1). I have downloaded and extracted it. I attempt to run it by changing to the extracted folder and executing ./eclipse This produces the following errors in the terminal: /usr/lib/gio/modules/libgiobamf.so: wrong ELF class: ELFCLASS64 Failed to load module: /usr/lib/gio/modules/libgiobamf.so /usr/lib/gio/modules/libgvfsdbus.so: wrong ELF class: ELFCLASS64 Failed to load module: /usr/lib/gio/modules/libgvfsdbus.so And then a dialog opens with this error message: JVM terminated. Exit code=13 /usr/bin/java -Dosgi.requiredJavaVersion=1.5 -XX:MaxPermSize=256m -Xms40m -Xmx384m -jar /opt/eclipse//plugins/org.eclipse.equinox.launcher_1.2.0.v20110502.jar -os linux -ws gtk -arch x86 -showsplash -launcher /opt/eclipse/eclipse -name Eclipse --launcher.library /opt/eclipse//plugins/org.eclipse.equinox.launcher.gtk.linux.x86_1.1.100.v20110505/eclipse_1407.so -startup /opt/eclipse//plugins/org.eclipse.equinox.launcher_1.2.0.v20110502.jar --launcher.overrideVmargs -exitdata 2f80031 -product org.eclipse.epp.package.java.product -clean -vm /usr/bin/java -vmargs -Dosgi.requiredJavaVersion=1.5 -XX:MaxPermSize=256m -Xms40m -Xmx384m -jar /opt/eclipse//plugins/org.eclipse.equinox.launcher_1.2.0.v20110502.jar I'd appreciate any help / insight. Update I should mention that I'm running 32 bit ubuntu and I'm trying to install 32 bit eclipse. Update #2 Oops - I just realized that I'm running 64 bit ubuntu, not 32 bit ubuntu.

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  • JMX Based Monitoring - Part One

    - by Anthony Shorten
    In all versions of the Oracle Utilities Application Framework there is an ability to use Java Management eXtensions (JMX) to both manage and monitor the various components of the product. This means that sites can use a JSR120 compliant JMX browser or JMX console to view or manage the components of the product with little or no configuration required. In each version we have progressively added JMX capabilities to allow IT groups more detailed information. In Oracle Utilities Application Framework V2.1 and above it was possible to use JMX on the Web Application Server provided Mbeans to allow you to monitor the online component of the product as well as manage the configuration. Also with a few additional java options it is possible to get a good level of detail about the Java Virtual machine including memory and thread usage. In Oracle Utilities Application Framework V2.2 and above, we added support for Java 5 statistics (Java enabled them by default), database pool statistics and also added the ability to manage and moinitor the batch component of the architecture. Now, in Oracle Utilities Application Framework V4 and above, we added support for Java 6 MXBeans, online management of the cache using JMX, additional JVM information and Performance monitoring using JMX. JMX allows the product to be managed from a common console such as Oracle Enterprise Manager, Tivoli, HP OpenView (and a lot more). Over the next week or so I will be compiling a set of blog entries discussing what is available (in summary format) using JMX and how to get access to the JMX statistics for your version of the product.

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  • links for 2010-06-03

    - by Bob Rhubart
    @rluttikhuizen: Fault handling in Oracle SOA Suite 11g "When it comes to technical faults," says  Oracle ACE Ronald van Luttikhuizen, "you probably do not want to design error handling in the process itself." (tags: soa oracleace oracle otn) Adrian Campbell: Enterprise Architecture and Zombies EA blogger Adrian Campbell invokes Harry Potter, the Lord of the Rings, Black Adder, and "Pride and Prejudice and Zombies" in this interpretation of Gartner's 10 EA pitfalls. (tags: entarch zombies gartner) Nathalie Roman: Oracle Forms -- alive and kicking Oracle ACE Director Nathalie Roman offers details on a recent Oracle Forms Modernization seminar.  (tags: oracle otn oracleace fusionmiddleware soa) Trond-Arne Undheim: Is Openness at the heart of the EU Digital Agenda? Trond-Arne Undheim shares some insight into the upcoming OpenForum Europe Summit 2010, to be held in Brussels. (tags: oracle otn entarch architect) Chris Raby: Oracle Financial Analytics Presentations and Photos Chris Raby shares details on Rittman Mead's series of seminars that combine the company's in-depth technical knowledge with a greater focus on the business perspective.  (tags: entarch bi architect oracle otn) June Oracle Technology Network NEW Member Benefits - books books and more books!!! Details on how OTN members can get discounts on books from APress, CRC, Pearson, and Packt Publishing.  (tags: oracle otn community books discounts) Manoj Neelapu: Oracle Service Bus + SOA in same server Manoj Neelapu's  tutorial covers on how to do create a domain in which SOA and Oracle Service Bus run in a single JVM . (tags: oracle otn soa architect)

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  • Java Spotlight Episode 84: Anil Gaur on JavaEE 7

    - by Roger Brinkley
    Tweet Interview with Anil Gaur, VP of Java Platform for Enterprise Edition and GlassFish Server, on JavaEE 7. Joining us this week on the Java All Star Developer Panel are Dalibor Topic, Java Free and Open Source Software Ambassador and Arun Gupta, Java EE Guy. Right-click or Control-click to download this MP3 file. You can also subscribe to the Java Spotlight Podcast Feed to get the latest podcast automatically. If you use iTunes you can open iTunes and subscribe with this link:  Java Spotlight Podcast in iTunes. Show Notes News Tori Wieldt - Judges Selected for Duke's Choice Awards Donald Smith - #OpenJDK interview in Java Magazine Henrik Ståhl - Java 7 adoption at 23% JavaOne Kicks Off with Sunday Keynotes at Masonic Auditorium Jersey 2.0 M4 JSF 2.2 Latest Snapshot NetBeans IDE 7.2 - Deploy to Cloud Events May 30, OTN Java Developer Day, Redwood Shores June 11-14, Cloud Computing Expo, New York City June 12, Boulder JUG June 13, Denver JUG June 13, Eclipse Juno DemoCamp, Redwoood Shore June 13, JUG Münster June 14, Java Klassentreffen, Vienna, Austria June 18-20, QCon, New York City June 26-28, Jazoon, Zurich, Switzerland July 5, Java Forum, Stuttgart, Germany July 30-August 1, JVM Language Summit, Santa Clara Feature InterviewAnil Gaur is the Vice President of Java Platform, Enterprise Edition, and GlassFish Server at Oracle in the Fusion Middleware Group. Is responsible for creation of Java EE Specifications, Reference Implementation, and Compatibility Test Suites. Leading the evolution on Java EE into Cloud and PaaS environment through the Java EE 7 standard. Prior to that, managed the delivery of Java EE 6 Platform and SDK which quickly gained momentum in enterprise application development and deployments. In this episode we talk about GlassFish 3.1 release. Mail Bag What’s Cool RFR (L): Adding core file parsing on Mac OS X to SA Sergio Del Valle @swdelvalle is the 1,000 @JavaSpotlight twitter follower

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  • Java Spotlight Episode 86: Tony Printezis on Garbage Collection First

    - by Roger Brinkley
    Interview with Tony Printezis on Garbage Collection First (GC1). Joining us this week on the Java All Star Developer Panel is Arun Gupta, Java EE Guy. Right-click or Control-click to download this MP3 file. You can also subscribe to the Java Spotlight Podcast Feed to get the latest podcast automatically. If you use iTunes you can open iTunes and subscribe with this link:  Java Spotlight Podcast in iTunes. Show Notes News JSR 358: A major revison of the Java Community Process - JCP 3.Next JAX-RS 2.0 Early Draft- Third Edition Events June 11-14, Cloud Computing Expo, New York City June 12, Boulder JUG June 13, Denver JUG June 13, Eclipse Juno DemoCamp, Redwoood Shore June 13, JUG Münster June 14, Java Klassentreffen, Vienna, Austria June 18-20, QCon, New York City June 19, CJUG, Chicago June 20, 1871, Chicago June 26-28, Jazoon, Zurich, Switzerland Jun 27, Houston JUG ?? July 5, Java Forum, Stuttgart, Germany Jul 13-14, IndicThreads, Delhi July 30-August 1, JVM Language Summit, Santa Clara Feature InterviewTony Printezis is a Principal Member of Technical Staff at Oracle, based in Burlington, MA. He has been contributing to the Java HotSpot Virtual Machine since 2006. He spends most of his time working on dynamic memory management for the Java platform, concentrating on performance, scalability, responsiveness, parallelism, and visualization of garbage collectors. He obtained a Ph.D. in 2000 and a BSc (Hons) in 1995, both from the University of Glasgow in Scotland. In addition, he is a JavaOne Rock Star, a title awarded for his highly rated JavaOne session on GC. Mail Bag What’s Cool JavaOne content selection is complete. Notifications done.

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  • Tab Sweep: Arquillian, Power Mac, PowerPC, JSP Performance, JMX Connection, ...

    - by arungupta
    Recent Tips and News on Java, Java EE 6, GlassFish & more : • Extreme Portability: OpenJDK 7 and GlassFish 3.1.1 on Power Mac G5! (Mark Heckler) • Using GlassFish domain templates to easily create several customized domains (Masoud Kalali) • OpenJDK 7 on Apple G5 PowerPC on Mac OS X 10.5.8 (John Yeary) • ENABLING REMOTE ADMINISTRATION FOR GLASSFISH (Adam Bien) • The Java EE 7 Feature List: Cloud Focused Upgrades (devx) • Improve JavaServer Pages Performance with Caching (distributedcaching) • Interactive Glassfish configuration and application deployment (mpashworth) • Allow JMX connection on JVM 1.6.x (Martin Muller) • Arquillian 1.0.0.Final released! Ready for GlassFish and WebLogic! Death to all bugs! (Markus Eisele) • Using GlassFish and APEXListener as backend for Apache so server APEX (Ronald Rod) • Installing and running Eclipse, Glassfish and Ubuntu 12.04 Precise for Web Applications (Connected Web) • Java EE 6 and modular JAX-RS services (Parijat) • ARQUILLIAN CONFIGURATION FOR EMBEDDED GLASSFISH 3.1.2 AND MAVEN 3 (Adam Bien) • Atmosphere .9 released (JeanFrancois Arcand) • Make JSF your friend again (Daniel Pfeifer)

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  • C#: Optional Parameters - Pros and Pitfalls

    - by James Michael Hare
    When Microsoft rolled out Visual Studio 2010 with C# 4, I was very excited to learn how I could apply all the new features and enhancements to help make me and my team more productive developers. Default parameters have been around forever in C++, and were intentionally omitted in Java in favor of using overloading to satisfy that need as it was though that having too many default parameters could introduce code safety issues.  To some extent I can understand that move, as I’ve been bitten by default parameter pitfalls before, but at the same time I feel like Java threw out the baby with the bathwater in that move and I’m glad to see C# now has them. This post briefly discusses the pros and pitfalls of using default parameters.  I’m avoiding saying cons, because I really don’t believe using default parameters is a negative thing, I just think there are things you must watch for and guard against to avoid abuses that can cause code safety issues. Pro: Default Parameters Can Simplify Code Let’s start out with positives.  Consider how much cleaner it is to reduce all the overloads in methods or constructors that simply exist to give the semblance of optional parameters.  For example, we could have a Message class defined which allows for all possible initializations of a Message: 1: public class Message 2: { 3: // can either cascade these like this or duplicate the defaults (which can introduce risk) 4: public Message() 5: : this(string.Empty) 6: { 7: } 8:  9: public Message(string text) 10: : this(text, null) 11: { 12: } 13:  14: public Message(string text, IDictionary<string, string> properties) 15: : this(text, properties, -1) 16: { 17: } 18:  19: public Message(string text, IDictionary<string, string> properties, long timeToLive) 20: { 21: // ... 22: } 23: }   Now consider the same code with default parameters: 1: public class Message 2: { 3: // can either cascade these like this or duplicate the defaults (which can introduce risk) 4: public Message(string text = "", IDictionary<string, string> properties = null, long timeToLive = -1) 5: { 6: // ... 7: } 8: }   Much more clean and concise and no repetitive coding!  In addition, in the past if you wanted to be able to cleanly supply timeToLive and accept the default on text and properties above, you would need to either create another overload, or pass in the defaults explicitly.  With named parameters, though, we can do this easily: 1: var msg = new Message(timeToLive: 100);   Pro: Named Parameters can Improve Readability I must say one of my favorite things with the default parameters addition in C# is the named parameters.  It lets code be a lot easier to understand visually with no comments.  Think how many times you’ve run across a TimeSpan declaration with 4 arguments and wondered if they were passing in days/hours/minutes/seconds or hours/minutes/seconds/milliseconds.  A novice running through your code may wonder what it is.  Named arguments can help resolve the visual ambiguity: 1: // is this days/hours/minutes/seconds (no) or hours/minutes/seconds/milliseconds (yes) 2: var ts = new TimeSpan(1, 2, 3, 4); 3:  4: // this however is visually very explicit 5: var ts = new TimeSpan(days: 1, hours: 2, minutes: 3, seconds: 4);   Or think of the times you’ve run across something passing a Boolean literal and wondered what it was: 1: // what is false here? 2: var sub = CreateSubscriber(hostname, port, false); 3:  4: // aha! Much more visibly clear 5: var sub = CreateSubscriber(hostname, port, isBuffered: false);   Pitfall: Don't Insert new Default Parameters In Between Existing Defaults Now let’s consider a two potential pitfalls.  The first is really an abuse.  It’s not really a fault of the default parameters themselves, but a fault in the use of them.  Let’s consider that Message constructor again with defaults.  Let’s say you want to add a messagePriority to the message and you think this is more important than a timeToLive value, so you decide to put messagePriority before it in the default, this gives you: 1: public class Message 2: { 3: public Message(string text = "", IDictionary<string, string> properties = null, int priority = 5, long timeToLive = -1) 4: { 5: // ... 6: } 7: }   Oh boy have we set ourselves up for failure!  Why?  Think of all the code out there that could already be using the library that already specified the timeToLive, such as this possible call: 1: var msg = new Message(“An error occurred”, myProperties, 1000);   Before this specified a message with a TTL of 1000, now it specifies a message with a priority of 1000 and a time to live of -1 (infinite).  All of this with NO compiler errors or warnings. So the rule to take away is if you are adding new default parameters to a method that’s currently in use, make sure you add them to the end of the list or create a brand new method or overload. Pitfall: Beware of Default Parameters in Inheritance and Interface Implementation Now, the second potential pitfalls has to do with inheritance and interface implementation.  I’ll illustrate with a puzzle: 1: public interface ITag 2: { 3: void WriteTag(string tagName = "ITag"); 4: } 5:  6: public class BaseTag : ITag 7: { 8: public virtual void WriteTag(string tagName = "BaseTag") { Console.WriteLine(tagName); } 9: } 10:  11: public class SubTag : BaseTag 12: { 13: public override void WriteTag(string tagName = "SubTag") { Console.WriteLine(tagName); } 14: } 15:  16: public static class Program 17: { 18: public static void Main() 19: { 20: SubTag subTag = new SubTag(); 21: BaseTag subByBaseTag = subTag; 22: ITag subByInterfaceTag = subTag; 23:  24: // what happens here? 25: subTag.WriteTag(); 26: subByBaseTag.WriteTag(); 27: subByInterfaceTag.WriteTag(); 28: } 29: }   What happens?  Well, even though the object in each case is SubTag whose tag is “SubTag”, you will get: 1: SubTag 2: BaseTag 3: ITag   Why?  Because default parameter are resolved at compile time, not runtime!  This means that the default does not belong to the object being called, but by the reference type it’s being called through.  Since the SubTag instance is being called through an ITag reference, it will use the default specified in ITag. So the moral of the story here is to be very careful how you specify defaults in interfaces or inheritance hierarchies.  I would suggest avoiding repeating them, and instead concentrating on the layer of classes or interfaces you must likely expect your caller to be calling from. For example, if you have a messaging factory that returns an IMessage which can be either an MsmqMessage or JmsMessage, it only makes since to put the defaults at the IMessage level since chances are your user will be using the interface only. So let’s sum up.  In general, I really love default and named parameters in C# 4.0.  I think they’re a great tool to help make your code easier to read and maintain when used correctly. On the plus side, default parameters: Reduce redundant overloading for the sake of providing optional calling structures. Improve readability by being able to name an ambiguous argument. But remember to make sure you: Do not insert new default parameters in the middle of an existing set of default parameters, this may cause unpredictable behavior that may not necessarily throw a syntax error – add to end of list or create new method. Be extremely careful how you use default parameters in inheritance hierarchies and interfaces – choose the most appropriate level to add the defaults based on expected usage. Technorati Tags: C#,.NET,Software,Default Parameters

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  • Yay! Oracle Solaris 11.1 Is Here!

    - by rickramsey
    Even the critters are happy. This is no cosmetic release. It's got TONS of new stuff for both system admins and system developers. In the coming weeks and months I'll highlight specific new capabilities, but for now, here are a few resources to get you started. What's New (pdf) Describes enhancements for sysadmins in: Installation System configuration Virtualization Security and Compliance Networking Data management Kernel/platform support Network drivers User environment And for system developers: Preflight Applications Checker Oracle ExaStack Labs (available to Oracle Partner Network Gold-level members for application certification) Oracle Solaris Studio Integrated Java Virtual Machine (JVM): Updates are now managed using the Image Packaging System (IPS) Migration guides and technology mapping tables for AIX, HP-UX and Red Hat Linux: Download Free downloads for SPARC and x86 are available, along with instructions and tips for using the new repositories and Image Packaging System. Tech Article: How to Upgrade to Oracle Solaris 11.1 You can upgrade using either Oracle's official Solaris release repository or, if you have a support contract, the Support repository. Peter Dennis explains how. Documentation Superbly written instructions from our dedicated cadre of world-renowned but woefully underpaid technical writers: Getting Started Installing, Booting, and Updating Establishing an Oracle Solaris Network Administering Essential Features Administering Network Services Securing the Operating System Monitoring and Tuning Creating and Using Virtual Environments Working with the Desktop Developing Applications Reference Manuals And more Training And don't forget the new online training courses from Oracle University! I really liked them. Here are my first and second impressions. Website Newsletter Facebook Twitter

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  • Python productivity VS Java Productivity

    - by toc777
    Over on SO I came across a question regarding which platform, Java or Python is best for developing on Google AppEngine. Many people were boasting of the increased productivity gained from using Python over Java. One thing I would say about the Python vs Java productivity argument, is Java has excellent IDE's to speed up development where as Python is really lacking in this area because of its dynamic nature. So even though I prefer to use Python as a language, I don't believe it gives quite the productivity boost compared to Java especially when using a new framework. Obviously if it were Java vs Python and the only editor you could use was VIM then Python would give you a huge productivity boost but when IDE's are brought into the equation its not as clear cut. I think Java's merits are often solely evaluated on a language level and often on out dated assumptions but Java has many benefits external to the language itself, e.g the JVM (often criticized but offers huge potential), excellent IDE's and tools, huge numbers of third party libraries, platforms etc.. Question, Does Python/related dynamic languages really give the huge productivity boosts often talked about? (with consideration given to using new frameworks and working with medium to large applications).

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  • C# via Java: Introduction

    - by simonc
    Originally posted on: http://geekswithblogs.net/simonc/archive/2013/11/08/c-via-java-introduction.aspxSo, I've recently changed jobs. Rather than working in .NET land, I've migrated over to Java land. But never fear! I'll continue to peer under the covers of .NET, but my next series will use my new experience in Java to explore the design decisions made in the development of the C# programming language. After all, the design of C# was based on Java 1.2, and both languages have continued to evolve since then, incorporating modern software engineering concepts and requirements. Exploring the differences and similarities between the two will (hopefully) give us a deeper understanding into why .NET is implemented the way it is, the trade-offs involved, and what choices were made when new features were designed and added to the language and framework. Among others, I'll be looking at differences in: Primitives Operators Generics Exceptions Accessibility Collections Delegates and inner classes Concurrency In my next post, I'll start off by looking at the type primitives available in each language, and how Java and C# actually incorporate two different concepts of primitive types in their fundamental language design and use. I'm also thinking of looking at the inner details of Java and the JVM in my blogs, as well as C# and the CLR. If you've got any comments or thoughts on this, please let me know.

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  • C# via Java: Introduction

    - by Simon Cooper
    So, I’ve recently changed jobs. Rather than working in .NET land, I’ve migrated over to Java land. But never fear! I’ll continue to peer under the covers of .NET, but my next series will use my new experience in Java to explore the design decisions made in the development of the C# programming language. After all, the design of C# was based on Java 1.2, and both languages have continued to evolve since then, incorporating modern software engineering concepts and requirements. Exploring the differences and similarities between the two will (hopefully) give us a deeper understanding into why .NET is implemented the way it is, the trade-offs involved, and what choices were made when new features were designed and added to the language and framework. Among others, I’ll be looking at differences in: Primitives Operators Generics Exceptions Accessibility Collections Delegates and inner classes Concurrency In my next post, I’ll start off by looking at the type primitives available in each language, and how Java and C# actually incorporate two different concepts of primitive types in their fundamental language design and use. I’m also thinking of looking at the inner details of Java and the JVM in my blogs, as well as C# and the CLR. If you’ve got any comments or thoughts on this, please let me know.

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  • links for 2010-05-10

    - by Bob Rhubart
    Announcing the MOS WCI "Community" (World of WebCenter Interaction) In this community you'll find a product related discussion forum moderated by Oracle WebCenter Interaction support engineers, recommended tips and tricks, links to knowledge base articles and best practices for setting up and administering up your environment. We hope you'll take a minute to have a look through the community. (tags: oracle otn webcenter enterprise2.0) Jason Williamson: Tuxedo Runtime for CICS and Batch Webcast "The notion that mainframes can be rehosted on open system is pretty well accepted. There are still some hold out CxO's who don't believe it, but those guys typically are not really looking to migrate anyway and don't take an honest look at the case studies, history and TPC reports." Jason Williamson (tags: oracle otn entarch tuxedo) Tom Hofte: Analyzing Out-Of-Memory issues in WebLogic 10.3.3 with JRockit 4.0 Flight Recorder Tom Hofte shows you "how to capture automatically an overall WLS system image, including a JFR image, after an out-of-memory (OOM) exception has occured in the JVM hosting WLS 10.3.3." (tags: oracle otn weblogic soa java) Install Control Center Agent on Oracle Application Server (Oracle Warehouse Builder (OWB) Weblog) Qianqian Wu show you how to Install and Configure the Application Server; Deploy the Control Center Agent to the Application Server; Optional Configuration Tasks (tags: oracle otn bi datawarehousing) Frank Buytendijk: BI and EPM Landscape "Organizations are getting more serious about ecosystem thinking. They do not evaluate single tools anymore for different application areas, but buy into a complete ecosystem of hardware, software and services. The best ecosystem is the one that offers the most options, in environments where the uncertainty is high and investments are hard to reverse. The key to successfully managing such an environment is middleware, and BI and EPM become increasingly middleware intensive. In fact, given the horizontal nature of BI and EPM, sitting on top of all business functions and applications, you could call them 'upperware.'" -- Frank Buytendijk (tags: oracle otn enterprisearchitecture bi)

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  • How do I install Apache Tomcat 7?

    - by Anupesh
    Troubleshooting with apache Tomcat 7 steps should be followed .... after downloading apache-Tomcat 7 // open terminal go to that downloading file folder in which tar.gz file is still. Untar the tar file tar -xzvf filename.tar.gz move a extracted directory of apache-Tomcat7 in current path sudo mv Directory_Name(Extracted eg.apache-Tomcat 7.0.32) /usr/local/Tomcat7 to set environment variable for Tomcat7 sudo nano /usr/local/Tomcat7/bin/setenv.sh then Nano editor will open .. JAVA_HOME =/usr/lib/jvm/java-6-sun export CATALINA_OPTS="$CATALINA_OPTS -Xms128m -Xmx1024m -XX:MaxPermSize=256m after hit ctrl+X to save file to set the role and username and password. sudo nano /usr/local/Tomcat7/conf/./tomcat-users.xml <role rolename="manager-gui" /> <role rolename="manager-script" /> <role rolename="manager-jmx" /> <role rolename="manager-status" /> <user username="admin" password="admin" roles="manager-gui,manager-script,manager-jmx,manager-status"/> Ctrl+X to save file If Port no confliction comes in a way then open file to change the port no. sudo nano /usr/local/Tomcat7/conf/./server.xml then change the connector port as you want....

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  • 10 Reasons Why Java is the Top Embedded Platform

    - by Roger Brinkley
    With the release of Oracle ME Embedded 3.2 and Oracle Java Embedded Suite, Java is now ready to fully move into the embedded developer space, what many have called the "Internet of Things". Here are 10 reasons why Java is the top embedded platform. 1. Decouples software development from hardware development cycle Development is typically split between both hardware and software in a traditional design flow . This leads to complicated co-design and requires prototype hardware to be built. This parallel and interdependent hardware / software design process typically leads to two or more re-development phases. With Embedded Java, all specific work is carried out in software, with the (processor) hardware implementation fully decoupled. This with eliminate or at least reduces the need for re-spins of software or hardware and the original development efforts can be carried forward directly into product development and validation. 2. Development and testing can be done (mostly) using standard desktop systems through emulation Because the software and hardware are decoupled it now becomes easier to test the software long before it reaches the hardware through hardware emulation. Emulation is the ability of a program in an electronic device to imitate another program or device. In the past Java tools like the Java ME SDK and the SunSPOTs Solarium provided developers with emulation for a complete set of mobile telelphones and SunSpots. This often included network interaction or in the case of SunSPOTs radio communication. What emulation does is speed up the development cycle by refining the software development process without the need of hardware. The software is fixed, redefined, and refactored without the timely expense of hardware testing. With tools like the Java ME 3.2 SDK, Embedded Java applications can be be quickly developed on Windows based platforms. In the end of course developers should do a full set of testing on the hardware as incompatibilities between emulators and hardware will exist, but the amount of time to do this should be significantly reduced. 3. Highly productive language, APIs, runtime, and tools mean quick time to market Charles Nutter probably said it best in twitter blog when he tweeted, "Every time I see a piece of C code I need to port, my heart dies a little. Then I port it to 1/4 as much Java, and feel better." The Java environment is a very complex combination of a Java Virtual Machine, the Java Language, and it's robust APIs. Combine that with the Java ME SDK for small devices or just Netbeans for the larger devices and you have a development environment where development time is reduced significantly meaning the product can be shipped sooner. Of course this is assuming that the engineers don't get slap happy adding new features given the extra time they'll have.  4. Create high-performance, portable, secure, robust, cross-platform applications easily The latest JIT compilers for the Oracle JVM approach the speed of C/C++ code, and in some memory allocation intensive circumstances, exceed it. And specifically for the embedded devices both ME Embedded and SE Embedded have been optimized for the smaller footprints.  In portability Java uses Bytecode to make the language platform independent. This creates a write once run anywhere environment that allows you to develop on one platform and execute on others and avoids a platform vendor lock in. For security, Java achieves protection by confining a Java program to a Java execution environment and not allowing it to access other parts of computer.  In variety of systems the program must execute reliably to be robust. Finally, Oracle Java ME Embedded is a cross-industry and cross-platform product optimized in release version 3.2 for chipsets based on the ARM architectures. Similarly Oracle Java SE Embedded works on a variety of ARM V5, V6, and V7, X86 and Power Architecture Linux. 5. Java isolates your apps from language and platform variations (e.g. C/C++, kernel, libc differences) This has been a key factor in Java from day one. Developers write to Java and don't have to worry about underlying differences in the platform variations. Those platform variations are being managed by the JVM. Gone are the C/C++ problems like memory corruptions, stack overflows, and other such bugs which are extremely difficult to isolate. Of course this doesn't imply that you won't be able to get away from native code completely. There could be some situations where you have to write native code in either assembler or C/C++. But those instances should be limited. 6. Most popular embedded processors supported allowing design flexibility Java SE Embedded is now available on ARM V5, V6, and V7 along with Linux on X86 and Power Architecture platforms. Java ME Embedded is available on system based on ARM architecture SOCs with low memory footprints and a device emulation environment for x86/Windows desktop computers, integrated with the Java ME SDK 3.2. A standard binary of Oracle Java ME Embedded 3.2 for ARM KEIL development boards based on ARM Cortex M-3/4 (KEIL MCBSTM32F200 using ST Micro SOC STM32F207IG) will soon be available for download from the Oracle Technology Network (OTN). 7. Support for key embedded features (low footprint, power mgmt., low latency, etc) All embedded devices by there very nature are constrained in some way. Economics may dictate a device with a less RAM and ROM. The CPU needs can dictate a less powerful device. Power consumption is another major resource in some embedded devices as connecting to consistent power source not always desirable or possible. For others they have to constantly on. Often many of these systems are headless (in the embedded space it's almost always Halloween).  For memory resources ,Java ME Embedded can run in environment as low as 130KB RAM/350KB ROM for a minimal, customized configuration up to 700KB RAM/1500KB ROM for the full, standard configuration. Java SE Embedded is designed for environments starting at 32MB RAM/39MB  ROM. Key functionality of embedded devices such as auto-start and recovery, flexible networking are fully supported. And while Java SE Embedded has been optimized for mid-range to high-end embedded systems, Java ME Embedded is a Java runtime stack optimized for small embedded systems. It provides a robust and flexible application platform with dedicated embedded functionality for always-on, headless (no graphics/UI), and connected devices. 8. Leverage huge Java developer ecosystem (expertise, existing code) There are over 9 million developers in world that work on Java, and while not all of them work on embedded systems, their wealth of expertise in developing applications is immense. In short, getting a java developer to work on a embedded system is pretty easy, you probably have a java developer living in your subdivsion.  Then of course there is the wealth of existing code. The Java Embedded Community on Java.net is central gathering place for embedded Java developers. Conferences like Embedded Java @ JavaOne and the a variety of hardware vendor conferences like Freescale Technlogy Forums offer an excellent opportunity for those interested in embedded systems. 9. Easily create end-to-end solutions integrated with Java back-end services In the "Internet of Things" things aren't on an island doing an single task. For instance and embedded drink dispenser doesn't just dispense a beverage, but could collect money from a credit card and also send information about current sales. Similarly, an embedded house power monitoring system doesn't just manage the power usage in a house, but can also send that data back to the power company. In both cases it isn't about the individual thing, but monitoring a collection of  things. How much power did your block, subdivsion, area of town, town, county, state, nation, world use? How many Dr Peppers were purchased from thing1, thing2, thingN? The point is that all this information can be collected and transferred securely  (and believe me that is key issue that Java fully supports) to back end services for further analysis. And what better back in service exists than a Java back in service. It's interesting to note that on larger embedded platforms that support the Java Embedded Suite some of the analysis might be done on the embedded device itself as JES has a glassfish server and Java Database as part of the installation. The result is an end to end Java solution. 10. Solutions from constrained devices to server-class systems Just take a look at some of the embedded Java systems that have already been developed and you'll see a vast range of solutions. Livescribe pen, Kindle, each and every Blu-Ray player, Cisco's Advanced VOIP phone, KronosInTouch smart time clock, EnergyICT smart metering, EDF's automated meter management, Ricoh Printers, and Stanford's automated car  are just a few of the list of embedded Java implementation that continues to grow. Conclusion Now if your a Java Developer you probably look at some of the 10 reasons and say "duh", but for the embedded developers this is should be an eye opening list. And with the release of ME Embedded 3.2 and the Java Embedded Suite the embedded developers life is now a whole lot easier. For the Java developer your employment opportunities are about to increase. For both it's a great time to start developing Java for the "Internet of Things".

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  • Talking JavaOne with Rock Star Raghavan Srinivas

    - by Janice J. Heiss
    Raghavan Srinivas, affectionately known as “Rags,” is a two-time JavaOne Rock Star (from 2005 and 2011) who, as a Developer Advocate at Couchbase, gets his hands dirty with emerging technology directions and trends. His general focus is on distributed systems, with a specialization in cloud computing. He worked on Hadoop and HBase during its early stages, has spoken at conferences world-wide on a variety of technical topics, conducted and organized Hands-on Labs and taught graduate classes.He has 20 years of hands-on software development and over 10 years of architecture and technology evangelism experience and has worked for Digital Equipment Corporation, Sun Microsystems, Intuit and Accenture. He has evangelized and influenced the architecture of numerous technologies including the early releases of JavaFX, Java, Java EE, Java and XML, Java ME, AJAX and Web 2.0, and Java Security.Rags will be giving these sessions at JavaOne 2012: CON3570 -- Autosharding Enterprise to Social Gaming Applications with NoSQL and Couchbase CON3257 -- Script Bowl 2012: The Battle of the JVM-Based Languages (with Guillaume Laforge, Aaron Bedra, Dick Wall, and Dr Nic Williams) Rags emphasized the importance of the Cloud: “The Cloud and the Big Data are popular technologies not merely because they are trendy, but, largely due to the fact that it's possible to do massive data mining and use that information for business advantage,” he explained. I asked him what we should know about Hadoop. “Hadoop,” he remarked, “is mainly about using commodity hardware and achieving unprecedented scalability. At the heart of all this is the Java Virtual Machine which is running on each of these nodes. The vision of taking the processing to where the data resides is made possible by Java and Hadoop.” And the most exciting thing happening in the world of Java today? “I read recently that Java projects on github.com are just off the charts when compared to other projects. It's exciting to realize the robust growth of Java and the degree of collaboration amongst Java programmers.” He encourages Java developers to take advantage of Java 7 for Mac OS X which is now available for download. At the same time, he also encourages us to read the caveats. Originally published on blogs.oracle.com/javaone.

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  • Talking JavaOne with Rock Star Raghavan Srinivas

    - by Janice J. Heiss
    Raghavan Srinivas, affectionately known as “Rags,” is a two-time JavaOne Rock Star (from 2005 and 2011) who, as a Developer Advocate at Couchbase, gets his hands dirty with emerging technology directions and trends. His general focus is on distributed systems, with a specialization in cloud computing. He worked on Hadoop and HBase during its early stages, has spoken at conferences world-wide on a variety of technical topics, conducted and organized Hands-on Labs and taught graduate classes.He has 20 years of hands-on software development and over 10 years of architecture and technology evangelism experience and has worked for Digital Equipment Corporation, Sun Microsystems, Intuit and Accenture. He has evangelized and influenced the architecture of numerous technologies including the early releases of JavaFX, Java, Java EE, Java and XML, Java ME, AJAX and Web 2.0, and Java Security.Rags will be giving these sessions at JavaOne 2012: CON3570 -- Autosharding Enterprise to Social Gaming Applications with NoSQL and Couchbase CON3257 -- Script Bowl 2012: The Battle of the JVM-Based Languages (with Guillaume Laforge, Aaron Bedra, Dick Wall, and Dr Nic Williams) Rags emphasized the importance of the Cloud: “The Cloud and the Big Data are popular technologies not merely because they are trendy, but, largely due to the fact that it's possible to do massive data mining and use that information for business advantage,” he explained. I asked him what we should know about Hadoop. “Hadoop,” he remarked, “is mainly about using commodity hardware and achieving unprecedented scalability. At the heart of all this is the Java Virtual Machine which is running on each of these nodes. The vision of taking the processing to where the data resides is made possible by Java and Hadoop.” And the most exciting thing happening in the world of Java today? “I read recently that Java projects on github.com are just off the charts when compared to other projects. It's exciting to realize the robust growth of Java and the degree of collaboration amongst Java programmers.” He encourages Java developers to take advantage of Java 7 for Mac OS X which is now available for download. At the same time, he also encourages us to read the caveats.

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  • Oracle Enterprise Manager sessions on the last day of the Oracle Open World

    - by Anand Akela
    Hope you had a very productive Oracle Open World so far . Hopefully, many of you attended the customer appreciation event yesterday night at the Treasures Islands.   We still have many enterprise manager related sessions today on Thursday, last day of Oracle Open World 2012. Download the Oracle Enterprise Manager 12c OpenWorld schedule (PDF) Oracle Enterprise Manager Cloud Control 12c (and Private Cloud) Time Title Location 11:15 AM - 12:15 PM Application Performance Matters: Oracle Real User Experience Insight Palace Hotel - Sea Cliff 11:15 AM - 12:15 PM Advanced Management of JD Edwards EnterpriseOne with Oracle Enterprise Manager InterContinental - Grand Ballroom B 11:15 AM - 12:15 PM Spark on SPARC Servers: Enterprise-Class IaaS with Oracle Enterprise Manager 12c Moscone West - 3018 11:15 AM - 12:15 PM Pinpoint Production Applications’ Performance Bottlenecks by Using JVM Diagnostics Marriott Marquis - Golden Gate C3 11:15 AM - 12:15 PM Bringing Order to the Masses: Scalable Monitoring with Oracle Enterprise Manager 12c Moscone West - 3020 12:45 PM - 1:45 PM Improving the Performance of Oracle E-Business Suite Applications: Tips from a DBA’s Diary Moscone West - 2018 12:45 PM - 1:45 PM Advanced Management of Oracle PeopleSoft with Oracle Enterprise Manager Moscone West - 3009 12:45 PM - 1:45 PM Managing Sun Servers and Oracle Engineered Systems with Oracle Enterprise Manager Moscone West - 2000 12:45 PM - 1:45 PM Strategies for Configuring Oracle Enterprise Manager 12c in a Secure IT Environment Moscone West - 3018 12:45 PM - 1:45 PM Using Oracle Enterprise Manager 12c to Control Operational Costs Moscone South - 308 2:15 PM - 3:15 PM My Oracle Support: The Proactive 24/7 Assistant for Your Oracle Installations Moscone West - 3018 2:15 PM - 3:15 PM Functional and Load Testing Tips and Techniques for Advanced Testers Moscone South - 307 2:15 PM - 3:15 PM Oracle Enterprise Manager Deployment Best Practices Moscone South - 104 Stay Connected: Twitter | Facebook | YouTube | Linkedin | Newsletter

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  • Do you think natively compiled languages have reached their EOL?

    - by Yuval A
    If we look at the major programming languages in use today it is pretty noticeable that the vast majority of them are, in fact, interpreted. Looking at the largest piece of the pie we have Java and C# which are both enterprise-ready, heavy-duty, serious programming languages which are basically compiled to byte-code only to be interpreted by their respective VMs (the JVM and the CLR). If we look at scripting languages, we have Perl, Python, Ruby and Lua which are all interpreted (either from code or from bytecode - and yes, it should be noted that they are absolutely not the same). Looking at compiled languages we have C which is nowadays used in embedded and low-level, real-time environments, and C++ which is still alive and kicking, when you want to get down to serious programming as close to the hardware as you can, but still have some nice abstractions to help you with day to day tasks. Basically, there is no real runner-up compiled language in the distance. Do you feel that languages which are natively compiled to executable, binary code are a thing of the past, taken over by interpreted languages which are much more portable and compatible? Does C++ mark an end of an era? Why don't we see any new compiled languages anymore? I think I should clarify: I do not want this to turn into a "which language is better" discussion, because that is not the issue at hand. The languages I gave as example are only examples. Please focus on the question I raised, and if you disagree with my statement that compiled languages are less frequent these days, that is totally fine, I am more than happy to be proved mistaken.

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  • How do I create a .deb file?

    - by JamesTheAwesomeDude
    Yes, I know that this question has been asked many times before, but none of the answers really helped. I'd like to package the Minecraft launcher (which has no proprietary code, AFAIK,) into a .deb file so that I can put it on a flash drive and share it with my friends. I have managed to install Minecraft it manually (put some files into /opt/minecraft, download an icon, and create a .desktop file in /usr/share/applications,) and I have made a shell script that completely automates the process, but it relies on wget to retrieve a few files, including the .desktop file. (It isn't a self-extracting archive, after all.) I'd like to be able to do this offline, as a lot of my friends have slow or no internet. (One of their internet lines was buried so shallowly that it actually got knocked out by the lawnmower.) I won't be loading it into a PPA or anything like that; I just want it to be a "formal" package that can be easily installed and uninstalled. (One thing that I would like is for sudo apt-get purge minecraft to also remove the .minecraft folder. It would also be nice to define the dependedcies as being able to accept OpenJDK or Sun's JVM.) Oh, just so you know, the Minecraft launcher is a .jar file, but I can very, very easily launch it via shell scripts. The exact command is right on the download page.

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  • The Java Specialist: An Interview with Java Champion Heinz Kabutz

    - by Janice J. Heiss
    Dr. Heinz Kabutz is well known for his Java Specialists’ Newsletter, initiated in November 2000, where he displays his acute grasp of the intricacies of the Java platform for an estimated 70,000 readers; for his work as a consultant; and for his workshops and trainings at his home on the Island of Crete where he has lived since 2006 -- where he is known to curl up on the beach with his laptop to hack away, in between dips in the Mediterranean. Kabutz was born of German parents and raised in Cape Town, South Africa, where he developed a love of programming in junior high school through his explorations on a ZX Spectrum computer. He received a B.S. from the University of Cape Town, and at 25, a Ph.D., both in computer science. He will be leading a two-hour hands-on lab session, HOL6500 – “Finding and Solving Java Deadlocks,” at this year’s JavaOne that will explore what causes deadlocks and how to solve them. Q: Tell us about your JavaOne plans.A: I am arriving on Sunday evening and have just one hands-on-lab to do on Monday morning. This is the first time that a non-Oracle team is doing a HOL at JavaOne under Oracle's stewardship and we are all a bit nervous about how it will turn out. Oracle has been immensely helpful in getting us set up. I have a great team helping me: Kirk Pepperdine, Dario Laverde, Benjamin Evans and Martijn Verburg from jClarity, Nathan Reynolds from Oracle, Henri Tremblay of OCTO Technology and Jeff Genender of Savoir Technologies. Monday will be hard work, but after that, I will hopefully get to network with fellow Java experts, attend interesting sessions and just enjoy San Francisco. Oh, and my kids have already given me a shopping list of things to get, like a GoPro Hero 2 dive housing for shooting those nice videos of Crete. (That's me at the beginning diving down.) Q: What sessions are you attending that we should know about?A: Sometimes the most unusual sessions are the best. I avoid the "big names". They often are spread too thin with all their sessions, which makes it difficult for them to deliver what I would consider deep content. I also avoid entertainers who might be good at presenting but who do not say that much.In 2010, I attended a session by Vladimir Yaroslavskiy where he talked about sorting. Although he struggled to speak English, what he had to say was spectacular. There was hardly anybody in the room, having not heard of Vladimir before. To me that was the highlight of 2010. Funnily enough, he was supposed to speak with Joshua Bloch, but if you remember, Google cancelled. If Bloch has been there, the room would have been packed to capacity.Q: Give us an update on the Java Specialists’ Newsletter.A: The Java Specialists' Newsletter continues being read by an elite audience around the world. The apostrophe in the name is significant.  It is a newsletter for Java specialists. When I started it twelve years ago, I was trying to find non-obvious things in Java to write about. Things that would be interesting to an advanced audience.As an April Fool's joke, I told my readers in Issue 44 that subscribing would remain free, but that they would have to pay US$5 to US$7 depending on their geographical location. I received quite a few angry emails from that one. I would have not earned that much from unsubscriptions. Most readers stay for a very long time.After Oracle bought Sun, the Java community held its breath for about two years whilst Oracle was figuring out what to do with Java. For a while, we were quite concerned that there was not much progress shown by Oracle. My newsletter still continued, but it was quite difficult finding new things to write about. We have probably about 70,000 readers, which is quite a small number for a Java publication. However, our readers are the top in the Java industry. So I don't mind having "only" 70000 readers, as long as they are the top 0.7%.Java concurrency is a very important topic that programmers think they should know about, but often neglect to fully understand. I continued writing about that and made some interesting discoveries. For example, in Issue 165, I showed how we can get thread starvation with the ReadWriteLock. This was a bug in Java 5, which was corrected in Java 6, but perhaps a bit too much. Whereas we could get starvation of writers in Java 5, in Java 6 we could now get starvation of readers. All of these interesting findings make their way into my courseware to help companies avoid these pitfalls.Another interesting discovery was how polymorphism works in the Server HotSpot compiler in Issue 157 and Issue 158. HotSpot can inline methods from interfaces that have only one implementation class in the JVM. When a new subclass is instantiated and called for the first time, the JVM will undo the previous optimization and re-optimize differently.Here is a little memory puzzle for your readers: public class JavaMemoryPuzzle {  private final int dataSize =      (int) (Runtime.getRuntime().maxMemory() * 0.6);  public void f() {    {      byte[] data = new byte[dataSize];    }    byte[] data2 = new byte[dataSize];  }  public static void main(String[] args) {    JavaMemoryPuzzle jmp = new JavaMemoryPuzzle();    jmp.f();  }}When you run this you will always get an OutOfMemoryError, even though the local variable data is no longer visible outside of the code block.So here comes the puzzle, that I'd like you to ponder a bit. If you very politely ask the VM to release memory, then you don't get an OutOfMemoryError: public class JavaMemoryPuzzlePolite {  private final int dataSize =      (int) (Runtime.getRuntime().maxMemory() * 0.6);  public void f() {    {      byte[] data = new byte[dataSize];    }    for(int i=0; i<10; i++) {      System.out.println("Please be so kind and release memory");    }    byte[] data2 = new byte[dataSize];  }  public static void main(String[] args) {    JavaMemoryPuzzlePolite jmp = new JavaMemoryPuzzlePolite();    jmp.f();    System.out.println("No OutOfMemoryError");  }}Why does this work? When I published this in my newsletter, I received over 400 emails from excited readers around the world, most of whom sent me the wrong explanation. After the 300th wrong answer, my replies became unfortunately a bit curt. Have a look at Issue 174 for a detailed explanation, but before you do, put on your thinking caps and try to figure it out yourself. Q: What do you think Java developers should know that they currently do not know?A: They should definitely get to know more about concurrency. It is a tough subject that most programmers try to avoid. Unfortunately we do come in contact with it. And when we do, we need to know how to protect ourselves and how to solve tricky system errors.Knowing your IDE is also useful. Most IDEs have a ton of shortcuts, which can make you a lot more productive in moving code around. Another thing that is useful is being able to read GC logs. Kirk Pepperdine has a great talk at JavaOne that I can recommend if you want to learn more. It's this: CON5405 – “Are Your Garbage Collection Logs Speaking to You?” Q: What are you looking forward to in Java 8?A: I'm quite excited about lambdas, though I must confess that I have not studied them in detail yet. Maurice Naftalin's Lambda FAQ is quite a good start to document what you can do with them. I'm looking forward to finding all the interesting bugs that we will now get due to lambdas obscuring what is really going on underneath, just like we had with generics.I am quite impressed with what the team at Oracle did with OpenJDK's performance. A lot of the benchmarks now run faster.Hopefully Java 8 will come with JSR 310, the Date and Time API. It still boggles my mind that such an important API has been left out in the cold for so long.What I am not looking forward to is losing perm space. Even though some systems run out of perm space, at least the problem is contained and they usually manage to work around it. In most cases, this is due to a memory leak in that region of memory. Once they bundle perm space with the old generation, I predict that memory leaks in perm space will be harder to find. More contracts for us, but also more pain for our customers. Originally published on blogs.oracle.com/javaone.

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  • The Java Specialist: An Interview with Java Champion Heinz Kabutz

    - by Janice J. Heiss
    Dr. Heinz Kabutz is well known for his Java Specialists’ Newsletter, initiated in November 2000, where he displays his acute grasp of the intricacies of the Java platform for an estimated 70,000 readers; for his work as a consultant; and for his workshops and trainings at his home on the Island of Crete where he has lived since 2006 -- where he is known to curl up on the beach with his laptop to hack away, in between dips in the Mediterranean. Kabutz was born of German parents and raised in Cape Town, South Africa, where he developed a love of programming in junior high school through his explorations on a ZX Spectrum computer. He received a B.S. from the University of Cape Town, and at 25, a Ph.D., both in computer science. He will be leading a two-hour hands-on lab session, HOL6500 – “Finding and Solving Java Deadlocks,” at this year’s JavaOne that will explore what causes deadlocks and how to solve them. Q: Tell us about your JavaOne plans.A: I am arriving on Sunday evening and have just one hands-on-lab to do on Monday morning. This is the first time that a non-Oracle team is doing a HOL at JavaOne under Oracle's stewardship and we are all a bit nervous about how it will turn out. Oracle has been immensely helpful in getting us set up. I have a great team helping me: Kirk Pepperdine, Dario Laverde, Benjamin Evans and Martijn Verburg from jClarity, Nathan Reynolds from Oracle, Henri Tremblay of OCTO Technology and Jeff Genender of Savoir Technologies. Monday will be hard work, but after that, I will hopefully get to network with fellow Java experts, attend interesting sessions and just enjoy San Francisco. Oh, and my kids have already given me a shopping list of things to get, like a GoPro Hero 2 dive housing for shooting those nice videos of Crete. (That's me at the beginning diving down.) Q: What sessions are you attending that we should know about?A: Sometimes the most unusual sessions are the best. I avoid the "big names". They often are spread too thin with all their sessions, which makes it difficult for them to deliver what I would consider deep content. I also avoid entertainers who might be good at presenting but who do not say that much.In 2010, I attended a session by Vladimir Yaroslavskiy where he talked about sorting. Although he struggled to speak English, what he had to say was spectacular. There was hardly anybody in the room, having not heard of Vladimir before. To me that was the highlight of 2010. Funnily enough, he was supposed to speak with Joshua Bloch, but if you remember, Google cancelled. If Bloch has been there, the room would have been packed to capacity.Q: Give us an update on the Java Specialists’ Newsletter.A: The Java Specialists' Newsletter continues being read by an elite audience around the world. The apostrophe in the name is significant.  It is a newsletter for Java specialists. When I started it twelve years ago, I was trying to find non-obvious things in Java to write about. Things that would be interesting to an advanced audience.As an April Fool's joke, I told my readers in Issue 44 that subscribing would remain free, but that they would have to pay US$5 to US$7 depending on their geographical location. I received quite a few angry emails from that one. I would have not earned that much from unsubscriptions. Most readers stay for a very long time.After Oracle bought Sun, the Java community held its breath for about two years whilst Oracle was figuring out what to do with Java. For a while, we were quite concerned that there was not much progress shown by Oracle. My newsletter still continued, but it was quite difficult finding new things to write about. We have probably about 70,000 readers, which is quite a small number for a Java publication. However, our readers are the top in the Java industry. So I don't mind having "only" 70000 readers, as long as they are the top 0.7%.Java concurrency is a very important topic that programmers think they should know about, but often neglect to fully understand. I continued writing about that and made some interesting discoveries. For example, in Issue 165, I showed how we can get thread starvation with the ReadWriteLock. This was a bug in Java 5, which was corrected in Java 6, but perhaps a bit too much. Whereas we could get starvation of writers in Java 5, in Java 6 we could now get starvation of readers. All of these interesting findings make their way into my courseware to help companies avoid these pitfalls.Another interesting discovery was how polymorphism works in the Server HotSpot compiler in Issue 157 and Issue 158. HotSpot can inline methods from interfaces that have only one implementation class in the JVM. When a new subclass is instantiated and called for the first time, the JVM will undo the previous optimization and re-optimize differently.Here is a little memory puzzle for your readers: public class JavaMemoryPuzzle {  private final int dataSize =      (int) (Runtime.getRuntime().maxMemory() * 0.6);  public void f() {    {      byte[] data = new byte[dataSize];    }    byte[] data2 = new byte[dataSize];  }  public static void main(String[] args) {    JavaMemoryPuzzle jmp = new JavaMemoryPuzzle();    jmp.f();  }}When you run this you will always get an OutOfMemoryError, even though the local variable data is no longer visible outside of the code block.So here comes the puzzle, that I'd like you to ponder a bit. If you very politely ask the VM to release memory, then you don't get an OutOfMemoryError: public class JavaMemoryPuzzlePolite {  private final int dataSize =      (int) (Runtime.getRuntime().maxMemory() * 0.6);  public void f() {    {      byte[] data = new byte[dataSize];    }    for(int i=0; i<10; i++) {      System.out.println("Please be so kind and release memory");    }    byte[] data2 = new byte[dataSize];  }  public static void main(String[] args) {    JavaMemoryPuzzlePolite jmp = new JavaMemoryPuzzlePolite();    jmp.f();    System.out.println("No OutOfMemoryError");  }}Why does this work? When I published this in my newsletter, I received over 400 emails from excited readers around the world, most of whom sent me the wrong explanation. After the 300th wrong answer, my replies became unfortunately a bit curt. Have a look at Issue 174 for a detailed explanation, but before you do, put on your thinking caps and try to figure it out yourself. Q: What do you think Java developers should know that they currently do not know?A: They should definitely get to know more about concurrency. It is a tough subject that most programmers try to avoid. Unfortunately we do come in contact with it. And when we do, we need to know how to protect ourselves and how to solve tricky system errors.Knowing your IDE is also useful. Most IDEs have a ton of shortcuts, which can make you a lot more productive in moving code around. Another thing that is useful is being able to read GC logs. Kirk Pepperdine has a great talk at JavaOne that I can recommend if you want to learn more. It's this: CON5405 – “Are Your Garbage Collection Logs Speaking to You?” Q: What are you looking forward to in Java 8?A: I'm quite excited about lambdas, though I must confess that I have not studied them in detail yet. Maurice Naftalin's Lambda FAQ is quite a good start to document what you can do with them. I'm looking forward to finding all the interesting bugs that we will now get due to lambdas obscuring what is really going on underneath, just like we had with generics.I am quite impressed with what the team at Oracle did with OpenJDK's performance. A lot of the benchmarks now run faster.Hopefully Java 8 will come with JSR 310, the Date and Time API. It still boggles my mind that such an important API has been left out in the cold for so long.What I am not looking forward to is losing perm space. Even though some systems run out of perm space, at least the problem is contained and they usually manage to work around it. In most cases, this is due to a memory leak in that region of memory. Once they bundle perm space with the old generation, I predict that memory leaks in perm space will be harder to find. More contracts for us, but also more pain for our customers.

    Read the article

  • Round-up: Embedded Java posts and videos

    - by terrencebarr
    I’ve been collecting links to some interesting blog posts and videos related to embedded Java over the last couple of weeks. Passing  these on here: Freescale blog – The Embedded Beat: “Let’s make it real – Internet of Things” Simon Ritter’s blog: “Mind Reading with Raspberry Pi” NightHacking with Steve Chin and Terrence Barr: “Java in the Internet of Things” NightHacking with Steve Chin and Alderan Robotics: “The NAO Robot” Java Magazine: “Getting Started with Java SE for embedded devices on Raspberry Pi” OTN video interview: “Java at ARM TechCon” OPN Techtalk with MX Entertainment: “Using Java and MX’s GrinXML Framework to build Blu-ray Disc and media applications” Oracle PartnerNetwork Blog: “M2M Architecture: Machine to Machine – The Internet of Things – It’s all about the Data” YouTube Java Channel: “Understanding the JVM and Low Latency Applications” Cheers, – Terrence Filed under: Mobile & Embedded Tagged: blog, iot, Java, Java Embedded, Raspberry Pi, video

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  • Round-up: Embedded Java posts and videos

    - by terrencebarr
    I’ve been collecting links to some interesting blog posts and videos related to embedded Java over the last couple of weeks. Passing  these on here: Freescale blog – The Embedded Beat: “Let’s make it real – Internet of Things” Simon Ritter’s blog: “Mind Reading with Raspberry Pi” NightHacking with Steve Chin and Terrence Barr: “Java in the Internet of Things” NightHacking with Steve Chin and Alderan Robotics: “The NAO Robot” Java Magazine: “Getting Started with Java SE for embedded devices on Raspberry Pi” OTN video interview: “Java at ARM TechCon” OPN Techtalk with MX Entertainment: “Using Java and MX’s GrinXML Framework to build Blu-ray Disc and media applications” Oracle PartnerNetwork Blog: “M2M Architecture: Machine to Machine – The Internet of Things – It’s all about the Data” YouTube Java Channel: “Understanding the JVM and Low Latency Applications” Cheers, – Terrence Filed under: Mobile & Embedded Tagged: blog, iot, Java, Java Embedded, Raspberry Pi, video

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  • Libgdx Box2d createfixture crashes vm intermittently

    - by user45021
    I have a hard to debug problem. I have a Box2D game which creates a wheeled vehicle. I want the vehicle body to reflect when it goes from moving left to moving right. to do this i set a flag in a changelistener on a button and then in update method i destroy and recreate the body facing the other way. it works fine most of the time but if i flip the vehicle several times quickly JVM crashes. no errors nothing in log. i added system.out.prints and the errors occur in the routine that instantiates the new body and before anything gets deleted/removed so i don't think the UI is trying to access null pointers. and if it was it should throw an error. M the crash seems to be at createFixture statements. but the work most of the first time. I tried debugging but the error doesn't happen much when the flips are slow. in any case createFixture drops fairly quickly into jni. Is this a Box2D bug? Is GC the issue? From Mission Control I see the GC is collecting on a period of ooh maybe 5s and flipping slower than that mostly works. how do i debug this? i am win7 64bit with 64bit at and jdk7 64bit. libgdx-0.9.9 and sometimes libgdx-nightly-20140215.

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