New Event with Web Sever pdf

Declaring an Event
You declare an event in a class intended to act as an event source. An event source is
usually a class that monitors its environment, and raises an event when something
significant happens. In the automated factory, an event source could be a class that
monitors the temperature of each machine. The temperature monitor class would raise a
“machine overheating” event if it detects that a machine has exceeded its thermal
radiation boundary (i.e. it has become too hot). An event maintains a list of methods to
call when it is raised. These methods are sometimes referred to as subscribers. These
methods should be prepared to handle the “machine overheating” event and take the
necessary corrective action: shut the machines down.
You declare an event in a way similar to declaring a field. However, because events are
intended be used with delegates, the type of an event must be a delegate, and you must
prefix the declaration with the event keyword. For example, here's the
StopMachineryDelegate delegate from the automated factory. I have relocated it to a new
class called TemperatureMonitor, which provides an interface to the various electonic
probes monitoring the temperature of the equipment (this is a more logical place for the
event than the Controller class):
class TemperatureMonitor
{
public delegate void StopMachineryDelegate();

}
You can define the MachineOverheating event, which will invoke the
stopMachineryDelegate, like this:
class TemperatureMonitor
{
public delegate void StopMachineryDelegate();
public event StopMachineryDelegate MachineOverheating;

}
The logic (not shown) in the TemperatureMonitor class automatically raises the
MachineOverheating event as necessary. An event maintains its own internal collection
of attached delegates, so there is no need to manually maintain your delegate variable.