The High Availability Framework provides components not only for detecting when processes terminate, but also for recovering from that termination.
The main component is a process called the High Availability Manager (HAM) that acts as a "smart watchdog". Your processes talk to the HAM using the HAM API. With this API you basically set up conditions that the HAM should watch for and take actions when these conditions occur. So the HAM can be told to detect when a process terminates and to automatically restart the process. It will even detect the termination of daemon processes.
In fact, the High Availability Manager can restart a number of processes, wait between restarts for a process to be ready, and notify the process that this is happening.
The HAM also does heartbeating. Processes can periodically notify the HAM that they are still functioning correctly. If a process specified amount of time goes by between these notifications then the HAM can take some action.
The above are just a sample of what is possible with the High Availability Framework. For more information, see the High Availability Framework Developer's Guide.