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Supervisor-type Service

Scenario​

A supervisor-type service is one used to start, stop, restart, and control other processes/services. Based on a configuration, the supervisor can start, stop, restart, or report the status of other services it controls. Additionally, the supervisor can monitor the status of a process and restart it if it terminates erroneously (e.g., due to a segmentation fault or other exception, or forced termination with a signal).

We aim to implement a supervisor-type service. It will have one or more configuration files and a control program that users will use to send commands to the service: start, stop, restart, status, read_conf, list.

Answer the following questions with "True" or "False" and justify your answer. The justification should be simple, 2-3 sentences for each answer.

Questions​

  1. The service can be implemented and run only on POSIX/UNIX systems. Answer: False

  2. The service starts/restarts other processes through fork()/exec() calls (or equivalents). Answer: True

  3. Communication between the control program and the supervisor-type service can be done via UNIX sockets. Answer: True

  4. The service must run in privileged mode (with root privileges). Answer: False

  5. The service will be able to stop processes started through commands transmitted via pipes. Answer: False

  6. The service will be able to detect the erroneous termination of started processes through a wait()/waitpid() call. Answer: True

  7. Two or more supervisor-type services can coexist on the same system. Answer: True

  8. The service is a CPU-intensive process. Answer: False

  9. The services started by the supervisor service can coexist as threads of the supervisor process. Answer: False

  10. The service can configure the started processes to have standard descriptors redirected to a /dev/null-like input. Answer: True

  11. The service can memory-map the configuration file. Answer: True