Entities

An entity has four roles:

• open - The entity reads the task configuration from rg_conf and opens the task.
• changed - When rg_conf is modified, the entity must find out if there is an impact on its managed tasks.
• reconf - The entity should reconfigure its tasks based on the old and new values of rg_conf.
• close - The entity should shut down its tasks.

For example, the DNS entity handles the DNS task according to OpenRG's rg_conf configuration database. It initiates the DNS task, and equips it with callback functions that enable it to search for locally configured host names. These names are entered either manually by the user using the Web-based management, or by the DHCP server, which dynamically allocates IP addresses to computers on the network.

The architectural advantage of this design is that the task is unaware of the configuration database format, nor of the methods of polling the DHCP server for a host name - all of these responsibilities are left to the entity.