In order for Jetty to serve content (static or dynamic) a ContextHandler must be created and added to Jetty in the appropriate place. A pluggable DeploymentManager exists in Jetty 7 to make this process easier. The Jetty distribution contains example DeploymentManager configurations to deploy WAR files found in a directory to Jetty, and to deploy Jetty context.xml files into Jetty as well.
The Deployment Manager is the heart of the typical webapp deployment mechanism; it operates as a combination of an Application LifeCycle Graph, Application Providers that find and provide Applications into the Application LifeCycle Graph, and a set of Bindings in the Graph to control the behavior of the deployment process.
Applications that are to eventually become Deployed must first enter be identified by an AppProvider, whose responsibility it is to provide Apps to the DeploymentManager.
There are two AppProvider's that come with the Jetty Distribution.
The default WebAppProvider can monitor a directory for *.war files and submit them to the Application LifeCycle Graph for deployment into a context with the same name as the *.war file itself.
The default ContextProvider can monitor a directory for *.xml files and using the Jetty Xml configurator create a ContextHandler (usually a WebAppContext) to the Application LifeCycle Graph.
Activating both at the same time is possible, but can be confusing because you must take care to either keep both systems deploying mutually exclusive webapps, or align naming conventions of context.xml style files with WAR and webapp directories.
Application LifeCycle Graph
The core feature of the DeploymentManager is the Application LifeCycle Graph.
The nodes and edges of this graph are pre-defined in Jetty along the most common actions and states found. These nodes and edges are not hardcoded, and can be adjusted and added to depending on need. (Such as any complex need for added workflow, approvals, staging, distribution, coordinated deploys for a cluster or cloud, etc...)
New Applications enter this graph at the Undeployed node, and are pushed through the graph via the use of the java.lang.String) DeploymentManager.requestAppGoal(App,String) method.
The responsibility for deploying, starting, stopping, undeploying is handled by a set of default AppLifeCycle.Binding's that define the standard behavior.
If you choose to, you can write your own AppLifeCycle.Binding's and assign them to anywhere on the Application LifeCycle graph.
Example's of new AppLifeCycle.Binding implementations that could be written:
- Validate the incoming Application.
- Prevent the deployment of known forbidden Applications.
- Submit the installation to an Application auditing service in a corporate environment.
- Distribute the Application to other nodes in the cluster or cloud.
- Email owner / admin of change of state of the Application.
There are four default bindings:
- StandardDeployer - will deploy the ContextHandler into Jetty in the appropriate place.
- StandardStarter - will set the ContextHandler to started and start accepting incoming requests
- StandardStopper - will stop the ContextHandler and stop accepting incoming requests.
- StandardUndeployer - will remove the ContextHandler from Jetty.
A fifth, non-standard binding, called DebugBinding, is also available for debugging reasons; It will Log the various transitions through the Application LifeCycle.