3.8. Seam and incremental hot deployment

Some support for incremental hot deployment is included during development when you deploy your Seam application as an exploded directory. Add the following line to components.xml to enable debug mode in Seam and Facelets: 
<core:init debug="true">

Warning

Hot deployment of Facelets does not work if the hot deployment scanner is not enabled for the server profile.
The following files may now be redeployed without requiring a full restart of the web application:
  • any Facelets page
  • any pages.xml file
If you want to change any Java code, you will still need to do a full restart of the application. In JBoss, this can be accomplished by touching the top-level deployment descriptor: application.xml for an EAR deployment, or web.xml for a WAR deployment.
Seam supports incremental redeployment of JavaBean components for a fast edit/compile/test cycle. To make use of this, the JavaBean components must be deployed into the WEB-INF/dev directory. Here, they will be loaded by a special Seam classloader instead of the WAR or EAR classloader.
This function has some limitations:
  • The components must be JavaBean components — they cannot be EJB3 beans. (Seam is working to remove this limitation.)
  • Entities can never be hot-deployed.
  • Components deployed with components.xml cannot be hot-deployed.
  • Hot-deployable components will not be visible to any classes deployed outside WEB-INF/dev.
  • Seam debug mode must be enabled and jboss-seam-debug.jar must be included in WEB-INF/lib.
  • The Seam filter must be installed in web.xml.
  • You may see errors if the system is placed under any load and debug is enabled.
For WAR projects created with seam-gen, incremental hot deployment is available out of the box for classes in the src/hot source directory. However, seam-gen does not support incremental hot deployment for EAR projects.