Best of this Week Summary 16 August - 22 August 2010

• Great performance analysis (PDF) between Java IO and Java NIO by Google engineer Paul Tyma. Java IO is performing about 25% better.
  


• Of course I have to mention Oracle's Java lawsuit against Google. Several viewpoints can be found here (more on the profit/free markets) and here (more elaborate and technical details) and here (Android == Java?).
  


• A short comparison between Spring Web Services and Apache CXF.
  


• Several short HTML5 tutorials by Bob Leah from IBM collected at one place.
  


• Five things you might not know about .jar files.
  
  
  

Best of this Week Summary 9 August - 15 August 2010

• A quick tutorial creating a Spring Roo application and deploying it on Google App Engine. And related to that, an article deploying Spring Security on GAE.
  


• A "concise summary of the key points of API design, in easily digestible form" by Joshua Bloch.
  


• Finally: jQuery is also working on a version that is for mobile devices.
  


• A short comparison of Google App Engine and Amazon EC2. They are not really comparable, but still useful when deciding where to host your site/service.
  


• A Big Data analytics equivalent for LAMP (Linux, Apache HTTP Server, MySQL and PHP) architecture based on Hadoop. Mentions Adobe and Facebook using several components. Interesting is the mentioning of Facebook which created a web-based tool, HiPal, that enables non-engineers to run queries on large data sets, view reports, and test hypotheses using familiar web browser interfaces. More details on how Facebook uses Hadoop can be found here.
  


• Gartner released their new 2010 Hype Cycle. Always useful to see if you missed any new trends :)
  
  
  

Best of this Week Summary 2 August - 8 August 2010

• How to utilize Externalization (faster, less flexible) for high performance applications instead of Serialization (slower, more flexible).
  


• A bunch of pros and cons of Wicket.
  


• An extensive tutorial on how to work with XML, JSON and Google's protocol buffers within Android applications. It shows how to "develop a Web service that converts CSV data into XML, JSON, and protocol-buffers formats. Then you'll build a sample Android application that can pull the data from the Web service in any of these formats and parse it for display to the user". Assumes Froyo 2.2. Also shows a short comparison in performance between the three protocols.
  


• A five part introduction to HTML5 focusing on the mobile web.
  


• Highlights from Black Hat and Defcon 2010. That means security stuff :).
  
  


• A list of (mostly obvious) performance problems identified at Zappos, Monster etc.
  


• A pretty comprehensive overview of Java code obfuscating including these types: name, strings, code and flow, incremental, watermarking etc.
  

Best of this Week Summary 26 July - 1 August 2010

• Pretty nasty, some application apparently depend on the the company name in the JDK! Including Eclipse, causing OutOfMemoryErrors since Oracle changed the name from 'Sun Microsystems, Inc' to 'Oracle'. Sounds like a magic constant somewhere... Though as it says here it had to be put in to work around another bug. Oracle rolled it back until JDK 7.
  


• Evolutionary architecture and emergent design: Leveraging reusable code, Part 1 and Part 2.
  


• A Spring MVC 3 Showcase, which should give you have a good idea of what the technology can do.It includes a sample project, along with a supporting slide presentation and screencast. After digging in, you should have a good understanding of what Spring MVC can do and get a feel for how easy it is to use.
  


• Some random Android tips/lessons learned.
  


• Java Iterator Quiz time!
  

Best of this Week Summary 19 July - 25 July 2010

• A short introduction to using the open source project Jericho to parse HTML. Jericho includes text extraction from HTML markup, rendering, formatting and compacting HTML.
  


• A nice list of both strategic and technical factors you should consider when making decisions about integration in the blogpost EAI: when tools can help.
  


• The BBC used interesting semantic technologies on their soccer Worldcup 2010 website. See the architecture below:
  
  


• Pretty basic article on using DateFormat in a multi-threading environment. Tricky because they are not synchronized. You should definitely also consider Joda Time and the new Date and Time APIs for Java 7 (JSR-310).
  


• An explanation of how Sonar feedback metrics can be integrated into the code/test/commit/build cycle for a quality feedback loop.
  

Best of this Week Summary 28 June - 18 July 2010

• How Google App Engine does session affinity explained. In short: as long as the requests from the client are within minutes (it seems) of each other, the requests will get send to the same node. If the time between two requests is longer, it might get sent to another node, potentially causing a noticable delay. A solution to prevent this is to send a 'ping' every minute from the client.
  


• Three Wicket unittesting tips.
  


• The CERT (Oracle) Secure Coding Standards for Java: "rules and recommended practices for secure programming in the Java Platform Standard Edition 6 environment. This is a work-in-progress and they actively seek your feedback and involvement in making this effort a success."
  


• Twitter was having problems deploying new versions of their site to thousands of servers. With a solution built on top of BitTornado (a modified version of Bittorrent), they were able to reduce deployment time from 40 minutes to 12 seconds! The solution named Murder (Python + Ruby) is available as open source.
  

Android performance tips

All videos and slides from sessions during Google's I/O conference last May 2010 are available here.

I watched The world of ListView and Writing zippy Android apps. Below are the items that were most interesting to me. They are all Android performance related.

The world of ListView

• 9:15: A View in Android costs about one or 2K of RAM
  


• 16:55: Call notifyDataSetChanged() (from the UI thread) when something in your adapter has changed.
  


• 18:27: getItemViewType() is used to make sure convertView is of the correct type in getView().
  


• 19:06: Make sure getViewTypeCount never changes. Note that it doesn't hurt performance if you always return say 10 even if you only have 2 different view types returned by getItemViewType().
  


• 30:13: Shows how to create a custom list selector in xml.
  


• 40:40: android:smoothScrollbar to prevent scrollbar changing size. Especially useful for listviews with items of which height can differ greatly
  


• 41:00: Use fill_parent instead of wrap_content in a ListView
  


• 53:10: If refreshing the whole screen via notifyDataSetChanged() is too much of a performance hit, you can try to get the visible position and use getChildAt() to figure out what view to update. Example code for that is here.
  


• 53:50: Use inflate(item, parent, false) to prevent relative layout attributes being ignored in a listview.
  

In general: don't try to outsmart the ListView by building your own caching, nor depend in any way on the order of getView(position) getting called.


Writing zippy Android apps

Zippy means non-janky which means sluggish, slow etc.

• 08:00: example apk of how not to do things/see how stuff performs. Includes small Perl sqllite wrapper script to see how much is being read from sqlite
  


• 15:00: read/writes I/O on emulator is a lot faster than on a real device
  


• 19:00: An AsyncTask can get killed before it finishes, e.g if the user hits the Home key. If it's important that the task finishes, use IntentService.
  


• 24:15: Profiling/tracing apps 'adb shell am profile ...' with the TraceView tool.
  


• 47:00: handling rotation when you don't want to reload your heavy objects: usegetLastNonConfigurationInstance() and onRetainNonConfigurationInstance(). See the Android reference for more info.
  


• 51:00: Think about using files instead of sqlite (if you have limited structured data for example)
  

Lessons learned Wicket + Spring + Hibernate + Mod4J project

At a recent project we used the following tools & frameworks:

• Java JDK 6
  


• Wicket 1.4.8
  


• Spring 2.5
  


• Hibernate 3.2.5
  


• Mod4J 1.2.1
  


• Tomcat 6
  


• Oracle XE 10g
  


• Maven 2
  


• Eclipse Galileo
  


• JUnit 4.8.1
  


• DbUnit 2.4.7
  


• SVN
  


• OpenSSO
  


• Subclipse SVN plugin
  


• Eclipse IAM (Integration for Apache Maven)
  


• JIRA
  


• Continuum Continuous Integration
  

Below are a couple of lessons learned which I remembered to write down:

Wicket

• In a ModalWindow you'd probably want to use a AjaxSubmitLink, not a SubmitLink, if you want to use modalWindow.setWindowClosedCallback(). See here for explanation.
  


• ajaxrequesttarget.addComponent: addComponent name might be a bit confusing for beginners. It means "add the component to the list of components be re-rendered/refreshed".
  


• An AjaxSubmitLink doesn't update the model when setDefaultFormProcessing() is set to false. Not totally illogical, but you still might run it to it when you don't expect it.
  


• Here are tips to validate related fields. (In the original the example code is missing.)
  


• AjaxSubmitLink: if you get a "Component-targetted feedback message was left unrendered. This could be because you are missing a FeedbackPanel on the page" warning in your Tomcat server console, it seems you have to tell in the onError() of the AjaxSubmitLink which feedback panel(s) you want to have updated.
  You get the warning even when you have feedback panels higher up in the tree of the (Base)Page. An example to update those panels could be:
  
Component infoFeedback = getPage().get("infoPanel");
target.addComponent(infoFeedback);
Component warnFeedback = getPage().get("warningPanel");
target.addComponent(warnFeedback);
Component errorFeedback = getPage().get("errorPanel");
target.addComponent(errorFeedback);

  This solution was inspired by these posts: post1, post2, post3, post4.
  


• To show/hide any HTML markup block dynamically, just wrap it with a WebMarkupContainer. In the code create that wrapper and make it visible or not depending on your requirements:
  
boolean makeVisible = false;
WebMarkupContainer blockContainer = new WebMarkupContainer("blockWrapper");
blockContainer.setVisible(makeVisible);
add(blockContainer);

  


• Sometimes you might get a popup when using a ModalWinow that says "Reloading this page will cause modal window to disappear" when you don't expect it. Check the logs/console, you might just got an exception in your app (after which Wicket tries to redirect to the error page, which causes the popup to show; at least that's my reasoning).
  

JUnit

• If JUnit can't find the Spring context.xml in the resources directory, then you have to add the resources dir to your Build path
  

Mod4J

• Does not really support LazyLoading so not very efficient for large "graphs" of data/dependencies. In those cases you could decide to skip the DTO layer and directly access the domain model.
  


• The Maven plugin IAM in Eclipse can be turned off for the Mod4J models project in Eclipse, otherwise it runs twice: once by Mod4J features, once by Maven (plugin).
  

Best of this Week Summary 15 June - 27 June 2010

• References to two small Google Guice Inversion of Control tutorials. Check also the comments re: Spring's current complexity.
  


• Nice 2D graphics tutorial for Android creating a vintage thermometer.
  A beginners tutorial creating a tic-tac-toe game for Android.
  


• How to combine Wicket panels with Google Analytics.
  

Best of this Week Summary 14 June - 20 June 2010

• A short comparison between Wicket and Rails.
  


• "A step by step guide of how to develop a simple web application using Google's Web Toolkit (GWT) for the rich client and Spring as the back – end, server side framework: GWT 2, Spring 3, JPA2, Hibernate 3.5. The sample web application will provide functionality to make CRUD (Create Retrieve Update Delete) operations to a database. For the data access layer we will use JPA over Hibernate and for a database we will use Hypersonic. Of course you can change the configuration and use whatever you like. We will deploy the web application to an Apache – Tomcat instance."
  


• Nice bunch of steps on how to setup an Android project that works in Eclipse and builds via Ant on the commandline. Anybody got a Maven variant of this?
  


• This might be the reason why the iPad and iPhone (< iPhone 4) don't support multitasking right now: there's no swap.
  On a side note: Objective-C (programming language for iPhone+iPad) has entered the programming language top 10, up from 45! Not really suprising with 200K+ apps in its app stores and Apple's Mac OSX share increasing. Java still on top but decreasing.
  

Best of this Week Summary 7 June - 13 June 2010

• When rewriting an app from scratch doesn't make sense, and when it might make sense.
  


• Java deadlocks through Cyclic Dependencies: title says it all.
  


• Carnegie Mellon University's CERT (Computer Emergency Response Team) has released the Basic Fuzzing Framework (BFF), which is a simplified version of automated dumb fuzzing and includes a Linux virtual machine that has been optimized for fuzz testing and a set of scripts to implement a software test. It helps identify and eliminate security vulnerabilities from software products.
  


• A nice (external) analysis of the FIFA World Cup website against performance best practices.
  


• "Nokia's set of learning and teaching materials on Java in Mobile Devices (JME/MIDP). In fact, it is Forum Nokia’s most comprehensive set of information ever. Included are five courses, 23 lectures, 25 lab exercises with source code, and more than 1,200 slides with notes. The material has been designed for university instructors and students, developers, and self-learners. Five main topics are covered:
  
  
  • Java ME basics
    
  
  
  • Multimedia
    
  
  
  • Networking and messaging
    
  
  
  • Games and graphics
    
  
  
  • Security
    
  
  Of course JME is not so sexy as Android these days, but Nokia still has the largest number of mobile phones out there. And most (even quite low end) support JME, so from a market perspective the potential is much higher than building apps for Android phones...
  


• Several CSS reset examples, including a few really short ones.
  

Best of this Week Summary 30 May - 6 June 2010

• Google Web Toolkit vs. Smart GWT: Which should you choose as front-end? Start immediately with Smart GWT, or start with GWT and pick SGWT components when needed? Some insights here.
  Related to that, you might want to check Vaadin: "Vaadin is an open source web application framework for rich Internet applications. In contrast to Javascript libraries and browser-plugin based solutions it features a server-side architecture, which means that the majority of the logic runs on the servers. Ajax technology is used at the browser-side to ensure a rich and interactive user experience. On client-side Vaadin is built on top of and can be extended with Google Web Toolkit. Vaadin utilizes Google Web Toolkit for rendering the resulting web page. While Google Web Toolkit operates only client-side (i.e. a browser's JavaScript engine) – which could lead totrust issues – Vaadin adds server-side validation to all actions. This means that if the client data is tampered with, the server notices this and doesn't allow it.
  Historically, Vaadin has been compared to Echo and ZK frameworks that use similar of server-side programming model. The server-side APIs are quite similar providing both events and GUI components, but the client-side (i.e. web browser) interaction differs in the way that Vaadin uses Java programmed GWT widgets, while ZK is jQuery based, and Echo has its own implementation. Currently, the most frequently compared frameworks include Adobe Flex, Google Web Toolkit, Apache Wicket and ICEfaces."
  


• A new open spec collaboration has started: OExchange, which is an open protocol for sharing any URL with any service on the web. Bigger parties involved are LinkedIn, Microsoft, Google.
  


• A new way of phishing: TabNabbing - phishing by switching background tab content. Discovered by Firefox's creative lead Aza Raskin. Biggest challenge seems to get the malicious Javascript on a site the user goes to.
  


• Google announced a partnership with VMWare (and thus SpringSource and thus Spring) at I/O by adding its (GTW) widgets to Spring and deployment to the VMWare cloud. In marketing speak: "This is VMware and Google's view of the power of using Spring along with Google's presentation widgets to get apps started in hours, delivered in days, and deployed in minutes". Below it's shown in a diagram:
  
  
  


• The iPad isn't without "errors" in its usability (UI) according to Jakob Nielsen. For example: cross-app UI experience is inconsistent, and for some reason almost no app supports scrolling and shows information only per page.
  


• "An overview of how to design websites and optimise them for Maemo, iPhone, Android, and a variety of touch and non-touch devices based on S60 on Symbian OS. After reading the document, you will have the basic knowledge you need to start developing mobile web pages that provide cross-browser-compatible content in a user-friendly manner. Furthermore, with the tips and advice contained in the document, you can avoid making design choices that could eventually lead to a dead end or poor design, thus saving time in implementing and debugging features that will not work".
  


• Show Slow: an open source tool that helps monitor various website performance metrics over time. It captures the results of YSlow and Page Speed rankings and graphs them, to help you understand how various changes to your site affect its performance
  

Best of this Week Summary 17 May - 23 May 2010

• Codelab ("tutorial") from Google that "shows how web application vulnerabilities can be exploited and how to defend against these attacks. The best way to learn things is by doing, so you'll get a chance to do some real penetration testing, actually exploiting a real application. The codelab is built around Jarlsberg, a small, cheesy web application that allows its users to publish snippets of text and store assorted files. "Unfortunately," Jarlsberg has multiple security bugs ranging from cross-site scripting and cross-site request forgery, to information disclosure, denial of service, and remote code execution. The goal of this codelab is to guide you through discovering some of these bugs and learning ways to fix them both in Jarlsberg and in general."
  


• A new IBM Redbook on WebSphere Messaging and High Availability has just been released.
  


• A cool Android with Hudson continuous integration. Led on mobile phone changes color depending on the build status. Remember the Lava Lamps version?
  


• Java dynamic proxies explained. They are for example used in Hibernate for lazy loading entities and in Spring for AOP. Also explains what CGLib proxies are for.
  

Best of this Week Summary 10 May - 16 May 2010

• Finally a new version of the OWASP Top 10 Web Security Vulnerabilities. Previous versions were from 2007 and 2004.
  


• Lower level 8 potential jQuery optimization tips.
  


• A post explaining implementing RSS feeds with new Spring 3 features like AbstractRssFeedView.
  


• Oracle's ADF is starting to support mobile clients too with ADF Mobile Client. The technology preview for Blackberry is available now. Here's a tutorial PDF that shows how to develop a basic mobile browser application and a native app.
  

Best of this Week Summary 03 May - 09 May 2010

• Nice overview of what's new in HTML5 on html, css and Javascript APIs.
  


• "Principles and best practices for building high performing and highly resilient WebSphere eXtreme Scale applications" or "How IBM Supports High Volume and High SLA Applications". Compare for example with GigaSpaces.
  


• What's the current standing of SOA after five years?
  


• An interesting project DIME which provides Dependency Injection for Java ME. Compare with Spring ME.
  


• Mod4j (Modeling for Java): an open source DSL-based environment for developing administrative enterprise applications. The DSL helps you generate the basic CRUD and code for defined business rules.
  

Clonezilla backup steps

In the last two years I had to get my harddisk replaced twice by a new one.
To minimize effort of setting up the new disk, I investigated which harddisk-copy program would best fit my needs, without complex setup things or complex instructions to create a bootable/live CD.

After trying several things, Clonezilla 1.2.2-31 did it for me.
I tried DriveImage XML, but that required me to make a streamlined CD for XP first, because I got a d:\i386\layout.inf not found error. I also looked at Paragon Backup & Recovery, but couldn't find how to create a live CD.

Creating a bootable live DVD was easiest with Clonezilla, and it's standalone, so no OS disks like Windows XP needed. The actual steps to make a backup a bit difficult for non-unix/linux people, but not impossible.
Below are the steps I now use to make a complete backup of my harddisk (including Windows) to a networked external disk via Samba.
Whether you can use these steps for your setup completely depends on your setup. Main reason for listing the steps here is so I have an easy reference to them :)

Prerequisites

• Make sure you have an external harddisk connected to your network.
  


• Make sure you have its IP address. If you're normally using DHCP, you might want to give it a fixed IP.
  


• Make sure you have enough diskspace left on that external harddisk
  


• To minimize network errors during the copying, you might want to use a network cable instead of a wireless connection. I definitely did that.
  


• I used it for Windows XP, but any OS should do (it makes a byte-by-byte copy of the source disk
  

Steps to make copy

1. Put the bootable CD/DVD in the drive to boot from it. Choose F8 or F12 at startup if you manually need to select your machine to boot from it.
   


2. Wait until the boot sequence is done
   


3. Choose language, and Don't touch keymap
   


4. Choose Start Clonezilla
   


5. Now you have to get the network card to get activated. That happens in the next steps
   


6. Choose as Mount dir: samba_server
   


7. Choose eth0. Choose DHCP
   


8. Enter the IP of the networked external disk. E.g: 192.168.1.70
   


9. I canceled the Domain configuration option
   


10. Enter the account to use to connect to the networked external disk
    


11. Pay attention when you enter the directory where the image must be stored. It is the directory in which the directory with the image information will be put. If you enter a non-existing directory, the mount (happens when you hit OK) will fail. Not a problem, just that you know. If the mount fails, just restart the process, this time with an existing path. Example path:
    
    

    /public/home/partimag



12. Hit OK. This will start the mount command. It will ask you for a password if applicable. When the command is successful, you'll see the filesystem mount points listed.
    


13. Choose Beginners Mode. Choose savedisk.
    


14. Enter a name for the image. I usually append some more identifying information to the prefilled filename, which is something like: 2010-05-02-18-img
    


15. Then choose the disk from the machine you want to make a backup for. For me it's only one: sda. Hit OK.
    


16. Now you should see a summary of the command, which looks like:
    
    

    /opt/drbl/sbin/ocs-sr -q2 -c -j2 -z1 -i 2000 -p true savedisk "2010-05-02-18-img" "sda"


Hit ENTER. That should start the backup. No errors should occur. My 500G harddisk with about 100G of data took about 4,5 hours to get backed up. One time I had an error in the output, saying something like the eth0 NIC was "gone". But the backup continued, and no other official errors were shown. It was not clear whether Clonezilla recovered successfully from the connection being away for a little while. Still, to be on the safe side, I made another backup, that had no network errors at all.

Steps to restore copy
These steps are about the same as making the copy, except that you select restoredisk instead of savedisk. But for completeness, here are the steps:

1. Choose language
   


2. Select Don't touch keymap
   


3. Select Start Clonezilla
   


4. Choose first option device_image
   


5. Choose samba_server
   


6. Choose eth0
   


7. Choose DHCP
   


8. Enter IP address of server you've stored the image on (e.g. 192.168.1.70)
   


9. Cancel domain
   


10. Enter account name to login on server
    


11. Enter as directory: /public/home/partimag (note it's the same as when making the copy)
    


12. Enter the password for the server. If correct, you'll see again the mount result (filesystem diskspace usage)
    


13. Choose Beginner
    


14. Choose Restore disk
    


15. Choose the image you want to restore (e.g 2010-05-02-18-img)
    


16. Choose target disk: sda
    


17. Now you should see a summary of the command, which looks like:
    
    

    /opt/drbl/sbin/ocs-sr -g auto -e1 auto -e2 -c -r -j2 -p true restoredisk "2010-05-02-18-img" "sda"


Hit ENTER. That should start the backup. No errors should occur. My 500G harddisk with about 100G of data took about 2,5 hours to restore.

Best of this Week Summary 26 April - 02 May 2010

• Google's Chief Java Architect Josh Bloch "discusses many of the problems facing the Java community, including the ineffectiveness of J2ME, licensing problems, Java 7's late ship date, and even the JCP issues that James Gosling often opined about. He points out that these problems predate the Oracle acquisition of Sun, so everyone should just stop pointing their fingers at Larry Ellison."
  


• Another Getting Started blogpost for a Mahout-Taste based movie recommendation engine, which uses Wicket as presentation layer.
  


• Martin Fowler explaining Inversion of Control and suggesting to call it the Dependency Injection pattern. Notes that the Service Locator pattern can also remove the dependency, just as the DI pattern tries to. Describes which of these options to use. Finally he also gives pros/cons for constructor vs setter injection. Also pros/cons for configuration in the code or via configuration files.
  


• Several Javascript performance-optimization tips taken at JSConf 2010.
  


• An article "which looks at various storage mechanisms - JDBC, JPA, JavaSpaces, Java Content Repository, MongoDB, and DB4O, primarily - from the perspective of how good they are at CRUD operations and queries". The conclusion is that there is no one "best" mechanism, each has its own best application.
  

Best of this Week Summary 19 April - 25 April 2010

• An introduction to Gizzard, an open sourced sharding framework (store data across multiple computers instead of on just one) which is used by Twitter.
  


• A hands-on tutorial of creating a Spring application that uses Hibernate as JPA provider and JTA for transaction demarcation. A simple Order Processing Message Driven Bean is implemented that showcases this integration. It is deployed on a WebLogic 10.3 server.
  


• Last week Jira from the Apache Foundation was compromised. Here's a description of how the hackers gained access via XSS.
  

Best of this Week Summary 12 April - 18 April 2010

• An advanced article on Spring Security regarding namespaces.
  


• A few pros/cons on when you'd want to use Amazon's EC2, Google's App Engine or maybe RackspaceCloud.
  TweetDeck uses GAE (Python) for some parts of their system, e.g sending emails, in combination with EC2.
  


• John Resig on improving the Javascript in your web app. Video & full transcript, including new features now available in jQuery 1.4. Mentioned are: delegation, live events, html fragments, javascript from CDN, additional header in Ajax calls, custom events, special events, themeability and customizability, i18n, and IE6 support.
  


• An older but still interesting PDF on Scrum and XP experience in a project of 40 people. They experimented for about a year on different team sizes, different sprint lenghts etc.
  

Best of this Week Summary 5 April - 11 April 2010

• Google recently released SkipFish, a free, open source, fully automated, active web application security reconnaissance tool/scanner. "It prepares an interactive sitemap for the targeted site by carrying out a recursive crawl and dictionary-based probes. The resulting map is then annotated with the output from a number of active (but hopefully non-disruptive) security checks. The final report generated by the tool is meant to serve as a foundation for professional web application security assessments."
  
  


• Great, lessons learned/experiences/comparison on using Wicket and GWT. Definitely also check the comments.
  


• Tim O'Reilly's interesting attempt on defining the internet operating system. What is it, what does it do etc.
  


• Seven tips on how to make your API more successful from NPR's Director of Application Development.
  


• Five myths about old developers (40+?) debunked.
  


• A interesting comparison between Oracle Coherence & GigaSpaces XAP from about a year ago. More feedback also here. OC and GX are two of the largest Java data/computing grid solutions.
  


• And yes it's true, James "Java" Gosling has also left Oracle, after Jonathan Schwartz already did earlier.
  

Best of this Week Summary 29 March - 04 April 2010

• A short overview on what the differences are using Java in Google App Engine (and shortly mentioned in MS Azure) compared to "regular" JEE apps.
  


• Three Java serialization options compared: Java Serialization, JSON Serialization and Google Protocol Buffers. Check also the comments here. Another benchmarking set can be found here.
  The protocol buffers solution was fastest in this test.
  


• The third edition of Mastering EJB, is now available for free download off of TSS as PDF. The new edition includes more than 30 percent revised material and five new chapters covering security, integration, best practices, new EJB 2.1 features, as well as the latest open source Java solutions
  


• Interesting read on the IT infrastructure (most of the article) in F1 racing.
  Some quotes: "each car has roughly 100 sensors placed in key data capture positions and send anywhere up to 20 gigabyes of data back to the pits during a race."
  "They are collecting four to six megabytes per lap. It depends on the track layout and the quality of the coverage but we transfer about 70 per cent in real time to the garage or the pits". And, did you know there's a connection with the factory during the race?
  


• A funny observation that CSS has quite something in common with Aspect Oriented Programming! Includes a table which shows the similarities.
  

Best of this Week Summary 22 March - 28 March 2010

• Whatever happened to programming? These days it is seems only glueing together a bunch of libraries... Where's the creativity? Well, I think you can now more and more focus on what your app can/should do, instead of re-inventing the wheel all the time. And if you have a real unique idea, you still will have to write those libs too :)
  


• Versioning REST services: "when developers need to create a new endpoint versus just adding data".
  


• A basic comparison between Kindle (JME) & Android Java development.
  

Android SDKs, screensizes and resolutions: comparable hardware

Trying to get an overview of the possible combinations of Android SDKs and screensizes and resolutions, *and* what physical devices are comparable, I came to the below overview. If you know some more comparable hardware, please let me know, I'll update the tables.

The first table shows the different screensizes defined as per Supporting Multiple Screens | Android Developers, mapped on real existing devices.

Id	Screensize, resolution, physical	Comparable hardware
A	QVGA (240x320, low density, small screen, 3.3”)	-
B	HVGA (320x480, medium density, normal screen, 3.9”)	HTC Hero 1.5 but really has 3.2”
C	WVGA800 (480x800, high density, normal screen, 3.9”)	Google Nexus One but really has 3.7”
D	WVGA854 (480x854 high density, normal screen, 4.1”)	Motorola Droid (aka Milestone) but really has 3.7” and Sony Ericsson Xperia X10 (screensize unclear)
E	WQVGA400 (240x400, low density, normal screen, 3.9”)	-
F	WQVGA432 (240x432, low density, normal screen, 4,1”)	-

The table below shows which SDK supports the above screensizes.

SDK	Screensize Id
1.5	B
1.6	B-D
2.0	B-F
2.0.1	B-F
2.1	B-F

Remarks:

• The total nr of possible sdk+screensize combinations is 19!
  


• Android has organized the screensizes and resolutions into three generalized sizes and three generalized densities, see here.
  


• To support all these resolutions, you don't have to create icons/images for all possible combinations. By default Android tries to scale resources. Up to a certain limit it could be acceptable to let it do it for you, minimizing the number of images to create.
  


• An example setting is minSdkVersion = 3, targetSdkVersion = 4 (where 3 = 1.5, 4 = 1.6). Targeting 1.6 ensures that different screensizes can be supported if the device has 1.6 or higher.
  


• Cool skins you can find here. If you look at the configuration files, you can validate whether the screensize and resolutions are actually what you expect.
  


• Sources: Droid, Nexus One, Hero, Xperia X10.
  

Best of this Week Summary 15 March - 21 March 2010

• Twitter and Digg are moving from MySQL to Cassandra (a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model; a Facebook opensourced project). The reason for Digg for the move "is the increasing difficulty of building a high-performance, write-intensive application on a data set that is growing quickly, with no end in sight. This growth has forced them into horizontal and vertical partitioning strategies that have eliminated most of the value of a relational database, while still incurring all the overhead".
  Twitter has about the same reason: "No single points of failure", "Highly scalable writes (we have highly variable write traffic)", and "A healthy and productive open source community".
  Twitter tried HBase, Voldemort, MongoDB, MemcacheDB, Redis, Cassandra, and HyperTable amongst others before deciding to go with Cassandra. Interesting to read is how they slowly rollout Cassandra to limited sets of users.
  An introduction to Cassandra to get it up and running can be found here.
  
  


• A short post on how to implement Automatic testing Oracle Service Bus using Hudson, Maven and SoapUI.
  


• What to expect from HTML5 for webdevelopers.
  

Best of this Week Summary 8 March - 14 March 2010

• How do the Spring 3.0 REST features compare to JAX-RS? Definitely also check the comments.
  


• Wicket IPageStore implementation using Hazelcast ("open source clustering and highly scalable data distribution platform").
  Wicket now powers the mobile sites for Wallmart and Wellsfargo. Main reason for chosing Wicket: "... makes it easy to support multiple different types of devices. The walmart mobile application supports different HTML for three categories of devices (L1: iPhones & challengers, L2: BlackBerries, L3: Plain Old Devices). These three experiences are supported by the same Java code on the server side."
  Great that the implementers have open sourced their components. Especially interesting is the 'wicket-stateless' component, since Wicket at its core is focused on managing stateful behaviour.
  Also great to read is that in Wicket 1.5 support for variable/unknown URLs will be available. In that post you can also read how to do that in Wicket 1.4.
  


• Great post on how MySpace tested their site live with 1 million concurrent virtual users (mixed with live users) using 800 EC2 instances. For example, the setup generated over 77,000 hits per second, not including live traffic. The article also includes 3 lessons learned.
  


• A short article on why eCommerce site Zappos (shoes and apparel) re-architected their site from Perl to a Java EE environment. Main reason for them was to better deal with scaling and demands on high performance. The website serves "millions of users/visitors daily and processes between 60-65.000 purchases every day". Includes some best practices, and a more-or-less infomercial on using Dynatrace as their application performance management solution.
  

Best of this Week Summary 1 March - 7 March 2010

• Of course is the contract between webservices more important than their internals.
  


• How the static analysis tool Coverity was turned into a commercial product. Includes caveats, lessons learned etc.
  Check also how you can measure code quality with Sonar.
  


• The updated 2010 list of most dangerous programming errors.
  


• Four presentations from John Resig on jQuery, and especially Query 1.4.
  

Best of this Week Summary 22 February - 28 February 2010

• A real life example on using Spring Integration to migrate content from multiple websites into Hippo CMS, handle errors, measure performance and deal with the fact that content could contain references to other content that is not imported yet.
  


• Summary of this article, which suggests rules for designing standard authentication schemes for REST API’s.
  


• Did you know JavaFX is already used on a big site like the Vancouver Winter Olympics 2010?
  


• Ten useful Java programming tips, maybe there are a few you don't know yet...
  

Best of this Week Summary 15 February - 21 February 2010

• Expected that Mozilla uses Agile everywhere, and definitely on its flagship Firefox? Think again, only recently they started to combine Agile and more traditional Waterfall as their new development model, dubbed "Lorentz".
  


• Tips for hardening your Tomcat installation. Other implementation guides, not only limited to Tomcat (also for example WebLogic) tips from U.S. DOD DISA (Defense Information Systems Agency) can be found here.
  


• Always interesting to at least quickly browse through: a review of the 1993 code of Doom. And more "today": the code of Doom for the iPhone reviewed.
  


• Think you know Javascript? Try one of these quizes!
  

Best of this Week Summary 8 February - 14 February 2010

• Five new features of Spring 3.0 described:
  
  
  • Spring Expression Language (SpEL)
    
  
  
  • Object/XML Mapping (OXM) module
    
  
  
  • Type-conversion system
    
  
  
  • Formatter SPI
    
  
  
  • RESTful web services support
    
  
  What new Ajax simplifications have been introduced can be found here.
  


• The Java EE 6 web tier introduces with Servlet 3.0 spec the ability for asynchronous processing of requests so that the thread may return to the container and perform other tasks. It also "adds annotation based configuration (@WebServlet, @ServletFilter and @WebServletContextListener) making the web.xml file optional, and introduces a new concept of web fragments."
  


• Introductionary article to Apache Click. One difference between Click and Wicket is that Click is stateless by design, while Wicket is stateful. Both can be configured their "opposite" model, though these have their own pros/cons.
  Another main difference is that that Click uses templates (Velocity by default) where Wicket does not.
  
  Sidestep: here's a bunch of nicely designed Wicket sites that scale (note: not really clear where the scalability statements come from).
  


• A 60 minutes presentation on how SOA is a hit at eBay.
  

Best of this Week Summary 1 February - 7 February 2010

• What's new in JSF 2.0 (facelets, composite components, partial state saving and Ajax).
  


• A couple of tips on how to avoid checking for null statements (focused on Java but applicable to any language).
  


• Tips/guidelines on how to use Spring on Google App Engine. Including a list of workarounds. This post has a more detailed step-by-step explanation for Spring 3.0 on GAE with a live example app.
  


• The work setup of several more or less famous technical guys ("nerds").