Tasks

As previously mentioned, a task is a set of functions that implement a certain protocol or service, for example PPP, DNS or HTTP. A task can be characterized as being self-contained and system independent. It does not rely on other tasks, configuration files or any other kind of outside help.

The OpenRG library, libOpenRG, provides the task with rudimentary services such as an event dispatch loop, memory allocation and logging functions. The entire configuration that a task may require is imparted as parameters to its open() function. The task's genuine work is actually performed by the callback function, a pointer which is also given as a parameter to the open() function.

It follows that tasks are inherently portable and reusable. To illustrate, the Ping task can be employed in two different ways:

• The DHCP server may use the Ping task to test whether an IP address it is about to lease is already taken by pinging the address in question. The task parameters in this case will be a ping packet, a brief time-out reply and callback functions. All of these are implemented in the DHCP code.
• The Web-based management may use the Ping task to implement a 'Connectivity Diagnostics Test' interface screen. The task parameters will be the number of ping attempts, a ten second time-out and callback functions. Again, these parameters are implemented in the Web-based management code.