There are other user interactions, like creating new tasks and pruning "dead" tasks, but we will not get into the details.
From time to time Wicket users ask questions related to how to deal with background jobs in Wicket. "How do I make Application or Session available to a background thread?
All these are available in the JVM world via Rhino but it is kind of slow...
Maybe it will get better with Nashorn with Java 8 but it will take some time.
Last but not least, I would like to thanks Martin Grigorov for guiding me in writing this small article, making nice amendments to it and for he's invaluable work maintaining Apache Wicket.
Lately I observe that the ecosystem provides much more (and better! For example there are tools to generate CSS like Less.js, SASS, Stylus, minimizers like Clean CSS, Uglify JS, linting tools like JSHint and JSLint and many more.