Jrebel

Introduction
(A) JRebel, formerly known as JavaRebel, is a plug-in for the Java Virtual Machine (JVM) that
enables instant reloading of changes made to a Java class file.
(B) Starting from version 1.4, the Java Virtual Machine includes a hot swapping feature that allows
developers to update the code on-the-fly during debugging.
(C) JRebel is an alternative solution to updating classes which does not require a debugging session
to be started. Instead it monitors the file system for changes and updates the classes in-memory
(D)JRebel is Java-based and usable on any operating system that supports Java. JRebel is IDE -
agnostic and designed for integration with various Java EE standards and Java application servers.
(E)JRebel supports major IDEs, including Eclipse, NetBeans and IntelliJ IDEA.
Features list
• Handles changes to class structures, frameworks and Java EE
• Eliminates memory leaks during development
• Supports all major Java application servers, IDEs and frameworks
• Eliminates build time during development
• Immediately visible code changes without redeploying
• Changes to method bodies
• Adding/removing Methods
• Adding/removing constructors
• Adding/removing fields
• Adding/removing classes
• Adding/removing annotations
• Changing static field value
• Adding/removing enum values
• Changing interfaces
3. Instant Builds
Skip builds for WAR directories
Skip builds for .WAR/.EAR class updates
Skip builds for .WAR/.EAR resource updates
Map multiple source dirs to one .WAR/.EAR target dir
Map classes and resources with include/exclude patterns
Map multiple source dirs with Ant-style patterns
Use system properties to make mapping machine-independent
Maven Plugin
Learning:
1) We have installed Jrebel plugin in Eclipse Helios using evaluation licence
2) Tested with one of the liferay Project
3) rebel.xml file to be created to enable Jrebel
4) Once Application up and running , whatever changes has been in jsp files and Java
files will get reflect without ant deploy or server restart.
5) This will reduce development time .
Recommendations:
1) Best suited for JEE project ,where any java/jsp changes required application server to restart
2) Other than Ext-Plugin,Restarting the Tomcat server is not required in Liferay Project.
3) Jrebel is only for developers tool , one more product this company called LiveRebel is for
Production hot fixes.
4) There is another open source tool called Javeleon is available in market.
5) Jrebel cost is more , for 100 developers/year cost is $36500 for enterprise License