System Agent has been gradually replaced by the Publish & Subscribe functionality since Symbian OS v8.0.
For more information about the use of Publish and Subscribe, see the Application Framework section.
Publish & Subscribe is an asynchronous notification method for delivering system-wide variables between processes and it also introduces a new method of communication. It is designed to be a secure way of communicating, providing dead-lock evasion and per-variable security policies (implemented in later Symbian OS versions).
Publish & Subscribe should be considered under any of the following conditions:
An event should be sent simultaneously to multiple places over the system.
Only the last value of the property is significant, not the intermediate values.
The source of the value is not significant. The value may have been set by any publisher with proper rights.
The interface to Publish & Subscribe is defined in the RProperty class.
For more information, refer to RProperty in the Symbian OS Library.