Overview of the
An client application,
such as a console or an adapter, utilizes the to determine where s are running. When a starts,
it registers with the broker:
- Hostname of the machine it is running on
- TCP port it is listening on.clients retrieve this information from the so that they can communicate with the .The registry maintains the following information:
- Name of the , including the host and TCP port it is running on.
- Status of each .The checks the status of each every five minutes by connecting to the host on which is running and determining if the process is running properly. If the is unable to connect or the process is not running, the changes the status of the to Dead.
- Runningindicates that the is able to communicate with the .
- Deadindicates that the exited unexpectedly or is unreachable. When a properly shuts down, it notifies the and the removes it from its registry.
- Unknownindicates that the was restarted and that it is querying its list of s to determine their state.
- Process ID of each . This is the process ID assigned by the host’s operating system. In some cases when the is restarted, the process ID of each is set to zero to indicate the does not know the process ID of the .
- Last time the state of the changed. This value is set when the registers with the and is updated if the determines that the is dead. When the restarts, it changes the status of s marked Unknown to Running or Dead.The changes the status of the to Dead when it cannot connect to the . However, the continues to try to connect to the every five minutes. If the succeeds in connecting to the , it changes its status back to Running.