HELIOS Base G8 User manual (Version 5.0.0)  

11 The notification server

11.1 The notification server program

The notification server system consists of the program “notifysrv”. It is created in the “HELIOSDIR/sbin” directory during the installation. HELIOS Base is configured to start “notifysrv” automatically when the HELIOS services are started.

“notifysrv” is responsible for receiving and distributing events from multiple local client processes and tools, and forwarding these to the listening target processes which have been registered for different kinds of events. “notifysrv” is a lightweight service with excellent performance in delivering messages fast and reliably, without blocking the sender or receiver processes and without polling.

The notification system handles internally used low-level events including:

“notifysrv” always needs to be active, otherwise the events will not be handled in the different processes. The server supports fail-safe operation in the case of major internal problems, and will automatically be restarted in case of failure. In this case all other processes will automatically continue to work with the restarted “notifysrv” daemon.

The “notifysrv” application supports a telnet monitoring connection to list processes which are registered to receive events and to see how many events have been sent so far. The command socket localhost 2017 connects to the monitoring port and allows observing the activity.

The following commands are supported:

        help - print a list of available commands
        quit - close connection
        status - show status information

See TelnetPort in 19.12 “Notification server preference keys” for a description of the preference which allows changing the “notifysrv” port number.

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HELIOS Manuals May 27, 2021