Launch events

A launch event occurs when one of the platform's components starts. For each launch event the platform provides a predefined action that runs as the event's handler. A developer plugs initialization logic into this handler. Likewise, a graceful application server stop runs the onStopping[] handler, into which shutdown logic is plugged.

Component	Handler	When the event occurs
Application server	SystemEvents.onStarted[]	Once per application server start, before the server begins accepting client connections.
Application server	SystemEvents.onFinallyStarted[]	Once per application server start, at the end of the start: after onStarted[] and after the stage at which a full start synchronizes the Reflection metadata with the database.
Application server	SystemEvents.onStopping[]	Once per graceful application server stop (SIGTERM, Ctrl+C, service stop), before RMI, the scheduler and other services are stopped. Not run if the server start failed (including in onFinallyStarted[]).
Desktop client	SystemEvents.onDesktopClientStarted[]	Once per desktop client launch, after the client has connected to the application server.
Web client	SystemEvents.onWebClientStarted[]	Once per web client launch, after the client has connected to the application server.

The handlers are abstract actions of the sequential form declared in the system module SystemEvents. Application initialization logic is attached to them through action extension. After a handler runs, the platform applies its changes to the database itself.

The Reflection objects of forms, navigator elements, properties and actions are synchronized with the source code between onStarted[] and onFinallyStarted[]: in onStarted[] a lookup by canonical name finds only the objects that already existed at an earlier start, so initialization that needs them — seeding the permissions of the security policy, for example — belongs in onFinallyStarted[]. Under a light start the synchronization is skipped, and elements added since the last full start are not found at all.

While onStopping[] runs, the server still accepts client connections and requests. The handler does not run when the process terminates abnormally (kill -9, a JVM crash, a power loss).

Language

Handler implementations are added with the ACTION+ statement.

Examples

lastStarted 'Last server start' = DATA DATETIME ();

onStarted() + {
    lastStarted() <- currentDateTime();
}

onWebClientStarted() + {
    MESSAGE 'Welcome!';
}