• Technical Overview
  • Overview
    • What is Jahia?
    • The closer View
    • Technical Requirements
    • Everything is Content, whatever the type or source
      • Integrator and Developer Customization
    • Integrated technologies
    • Architecture Overview
    • Modules
    • Jahia's Different Actors
  • Web Layers
    • Content Flows
    • Templates and Views
    • The Jahia Template Studio
      • Page templates
      • Content Templates
    • REST API
      • Actions
      • Example : native iPhone/iPad application
    • Mobile Rendering
    • Macros
    • Filters
  • Back-end Layer
    • Workflow
    • JBoss Drools and event listeners
    • File Repository
    • Searching and Indexing
      • Full text queries using search tag librairies
      • Query Languages
    • Enterprise Jahia Tool - Authentication and Authorization
    • Import / Export
    • Enterprise Jahia Tool - Distant Server Publications
    • Portlets
      • Portlets vs. Modules
  • Enterprise Jahia Tool - Optimizing deployment and performance
  • Additional Resources

JBoss Drools and event listeners

Often, as modifications of content happen, integrators will face the need to perform a specific action when an event occurs. In previous versions of Jahia, event listeners could be either written in Java classes or in JSP files, or even Groovy scripts. In version 6.5, it was replaced with a much more powerful and easier to use rule system based on JBoss Drools. An example of such a rule is given below:

rule "Image update"
salience 25
#Rebuild thumbnail for an updated image and update height/width
when
A file content has been modified
- the mimetype matches image/.*
then
Create an image "thumbnail" of size 150
Create an image "thumbnail2" of size 350
Set the property j:width of the node with the width of the image
Set the property j:height of the node with the height of the image
Log "Image updated " + node.getPath()
end

As you can see rules are similar to the English language formulation and this makes it easy for integrators to use and read. Of course the vocabulary of conditions, making it easy to respond to any event with any action.