hot deploy in embedded jetty

Question

I have a Spring Roo project and I use mvn jetty:run to run my app. The only problem is changes to the *.java classes do not hot deploy, while changes to *.jspx hot deploy fine.

So how can I configure mvn jetty to hotdeploy for java classes?

Solution

You need to set the scanIntervalSeconds to a value greater than 0 to enable it:

scanIntervalSeconds - The interval in seconds to scan the webapp for changes and restart the context if necessary. Ignored if reload is enabled. Disabled by default. Default value is: 0.

So the configuration might looks like this:

<plugin>
  <groupId>org.mortbay.jetty</groupId>
  <artifactId>maven-jetty-plugin</artifactId>
  <version>6.1.22</version>
  <configuration>
    <scanIntervalSeconds>1</scanIntervalSeconds>
  </configuration>
</plugin>

Once enabled, the jetty maven plugin will scan the directory defined in classDirecory (which points to ${project.build.outputDirectory} by default i.e. target/classes) for changes.

You then just need to have your IDE compile classes in target/classes (or to run mvn compile) and Jetty will restart the context upon changes on Java classes.

Comments

[tholu]

There are 404 errors while Jetty redeploys the classes. Any suggestion how to avoid them? Also see this question: stackoverflow.com/questions/23343243/…

[tholu]

Unfortunately redeployment with zero downtime requires a lot of effort in the Java world :( Edit: Will try this: rafaelsteil.com/zero-downtime-deploy-script-for-jetty