JANOS supplies a Message Pump wherein messages of various types may be circulated between processes or application. These messages may be user defined.
Message numbers below 1024 (0x400) are RESERVED by the system.
The following are the system defined message types.

SM_SHUTDOWN (0x01)

This message is generated by the system prior to shutdown. When received applications MUST forward the message by returning it to the pump and exit in an expeditious fashion. The JNIOR is about to reboot.

SM_PROBE (0x02)

This message is generated by the system periodically. When receive applications MUST forward the message by returning it to the pump. This is used to detect listeners that are no longer responding or that are not properly forwarding messages. The system expects to see this message return to it in a prompt fashion.

SM_GCRUN (0x10)

This message indicates that the Garbage Collection (GC) has completed. When received applications MUST forward the message by returning it to the pump.

SM_WATCHDOG (0x11)

This message is generated by a application watchdog configured to send then message on timer expiration.

SM_SYSLOGMSG (0x12)

System log messages can be sent to an external Syslog Server. This message also passes the log information to listening applications.

SM_PWRLOST (0x20)

When Ride-Thru Power support is available this indicates the lost of external power.

SM_PWRGOOD (0x21)

When Ride-Thru Power support is available this indicates that external power has been restored.

SM_PWRREADY (0x22)

When Ride-Thru Power support is available this indicates that the supply is fully charged and ready to provide maximum holding capacity.

SM_REGUPDATE (0x40)

This message is generated whenever a registry entry is updated or removed. When received application MUST forward the message by returning it to the pump.

SM_WEBSTARTUP (0x60)

Message sent when the Web Server process is activated.

SM_WEBSHUTDOWN (0x61)

Message sent when the Web Server process is terminated.

SM_PROTCMDMSG (0x70)

This message is generated when the JNIOR Protocol receives a custom command message. When received an application MUST either forward the message or provide a SM_PROTCMDRESP response.

SM_PROTCMDRESP (0x71)

This message is generated by an application in response to a SM_PROTCMDMSG command message. It is intended for the JNIOR Protocol server. When received applications MUST forward the message by returning it to the pump.

SM_PIPEOPEN (0x80)

This message is sent by the Web Server when a piped websocket connection has been established. The message contains the client IP Address and Port as well as the target message number.

SM_PIPECLOSE (0x81)

This message is sent by the Web Server when a piped websocket connection has terminated. The message contains the client IP Address and Port as well as the original targeted message number.

SM_USER (0x400)

Lowest allowed user defined message number. Applications that intend to exchange messages SHOULD attempt to define globally unique message identifiers. These must be values from 1024 and up. Message numbers below SM_USER are RESERVED by the system.