[jboss-as7-dev] Graceful Shutdown

We've worked out the rough outline of how graceful shutdown will work in AS7. The process of graceful shutdown actually is reflected by a number of states: 1. Running - all services acting normally 2. Suspending - services refuse new "permits" (see below), existing permits are allowed to be retained (and threads running under such a permit may still acquire new permits) 3. Suspended - no permits are present and none may be issued 4. Shutting Down - our existing server stop process The following transitions are allowed: 1. Running → Suspending: Transition occurs at user request (to suspend or gracefully shut down). 2. Suspending → Suspended: Transition occurs when all permits are cleared. 3. Suspending → Running: Transition occurs at user request (to exit suspend mode or cancel graceful shutdown before it completes). 4. Suspended → Running: Transition occurs at user request (to exit suspend mode). 5. Suspended → Shutting Down: Transition occurs automatically (if a graceful shutdown was requested) or at user request (if a shut down request of any kind is entered in the Suspended state). 6. Running → Shutting Down: Transition occurs at user request (to shut down the server "un-gracefully"). These "permits" are issued by the "Shutdown Manager", whose job is to manage these states. They are issued corresponding to the following events: 1. The invocation of an EJB method 2. The creation of a web session 3. A creation of a transaction 4. Probably some situations involving HQ and/or JCA When a permit cannot be issued due to the server shutting down, a standard exception message should be produced so that the user can see a familiar error message regardless of what mechanism is used to access the server. -- - DML