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Distributed transactions in Spring, with and without XA

While it's common to use the Java Transaction API and the XA protocol for distributed transactions in Spring, you do have other options. The optimum implementation depends on the types of resources your application uses and the trade-offs you're willing to make between performance, safety, reliability, and data integrity. In this JavaWorld feature, SpringSource's David Syer guides you through seven patterns for distributed transactions in Spring applications, three of them with XA and four without.

http://www.javaworld.com/javaworld/jw-01-2009/jw-01-spring-transactions.html

openHAB: open Home Automation Bus

       

Click here to download:

openHAB_open_Home_Automation_B.zip (350 KB)

JMXTerm: command line based interactive JMX client

Jmxterm is an open source command line based interactive JMX client. It's designed to allow user to access JMX from command line without graphical environment. In another word, it's a command line based jconsole.

Internally Jmxterm depends on JDK jconsole library but it doesn't require graphical environment(such as X in linux) at runtime.

http://wiki.cyclopsgroup.org/jmxterm 

Akka: simpler Scalability, Fault-Tolerance, Concurrency & Remoting through Actors

Akka is the platform for the next generation event-driven, scalable and fault-tolerant architectures on the JVM.

http://www.akkasource.org/

Scala Example:

 1 // creates an actor on the remote node 
 2     val service = actor("remote.node", 9999) {
 3       case fun => reply(fun())
 4     }
 5 
 6     // creates a processing function 
 7     val processingFun = () => ...
 8 
 9     // sends function to remote node 
10     service ! processingFun

Tomcat MemoryLeakProtection

Tomcat's new memory leak prevention and detection
http://www.tomcatexpert.com/blog/2010/04/06/tomcats-new-memory-leak-preventio...

Notes regarding implementation of Tomcats MemoryLeakProtection
http://wiki.apache.org/tomcat/MemoryLeakProtection

JreMemoryLeakPreventionListener
http://svn.apache.org/viewvc/tomcat/trunk/java/org/apache/catalina/core/JreMe...

Jansi: java library use ANSI codes to format console output

Jansi is a small java library that allows you to use ANSI escape sequences to format your console output which works even on windows.

http://jansi.fusesource.org/

28 Rich Data Visualization Tools

List of 28 Rich Data Visualization Tools

http://www.insideria.com/2009/12/28-rich-data-visualization-too.html

javamelody: monitoring of JavaEE applications

http://code.google.com/p/javamelody/

The goal of JavaMelody is to monitor Java or Java EE applications servers in QA and production environments. It is not a tool to simulate requests from users, it is a tool to measure and calculate statistics on real operation of an application depending on the usage of the application by users.

JavaMelody is opensource (LGPL) and production ready: in production in an application of 25 person years. JavaMelody is easy to integrate in most applications and is lightweight (no profiling and no database).

JavaMelody is mainly based on statistics of requests and on evolution charts.

It allows to improve applications in QA and production and help to:

* give facts about the average response times and number of executions
* make decisions when trends are bad, before problems become too
serious
* optimize based on the more limiting response times
* find the root causes of response times
* verify the real improvement after optimizations

It includes summary charts showing the evolution over time of the following indicators:

* Number of executions, mean execution times and percentage of
errors of http requests, sql requests or methods of business
façades (if EJB3 or if Spring)
* Java memory
* Java CPU
* Number of user sessions
* Number of jdbc connections

These charts can be viewed on the current day, week, month or year.

JavaMelody includes statistics of predefined counters (as of today http requests, sql requests and methods of business façades if EJB3 or if Spring) with, for each counter :

* A summary indicating the overall number of executions, the average
execution time, the cpu time and the percentage of errors.
* And the percentage of time spent in the requests for which the
average time exceeds a configurable threshold.
* And the complete list of requests, aggregated without dynamic
parameters with, for each, the number of executions, the mean
execution time, the mean cpu time, the percentage of errors and an
evolution chart of execution time over time.
* Furthermore, each http request indicates the size of the flow
response, the mean number of sql executions and the mean sql time.

It also includes statistics on http errors, on warnings and errors in logs and on data caches if ehcache.

An optional and independent collect server may be used if necessary to unload the application of storage management, and of reports generation and to centralize the data of clustered applications or of several applications.

Java System properties for Apple's Java

http://developer.apple.com/mac/library/documentation/Java/Reference/Java_PropertiesRef/Articles/JavaSystemProperties.html

YouDebug: Java program that lets you script a debug session through Groovy

Here is the problem; your program fails at a customer's site with an exception, but you can't (or don't want to) reproduce the problem on your computer, because it's too time consuming. If only you could attach the debugger and collect a few information, you can rapidly proceed on fixing the problem. But running a debugger at a customer's site is practically impossible; if the user isn't a techie, it's out of question. Even if he is, you'd still need the source code loaded up in the IDE, then you have to explain to him where he needs to set breakpoints and what to report back to you. It's just too much work.

That's where YouDebug comes into play. YouDebug is a Java program that lets you script a debug session through Groovy. You can think of it as a programmable, non-interactive debugger --- you can create a breakpoint, evaluate expressions, have it dump threads, and a lot more, without requiring any source code. Your customer can just run the tool with the script you supplied, without any knowledge about Java.

YouDebug uses the same Java Debug Interface that IDEs use, so from the point of view of your program, YouDebug behaves as a debugger. Therefore you need not do anything special with your program.

In this way, the troubleshooting of your program gets a lot easier.

http://youdebug.kenai.com/