C# 4 and .NET 4

678 ❘ ChaPTer 25 windOws services
The quoteServer variable is declared as a private member in the class:
namespace Wrox.ProCSharp.WinServices
{
public partial class QuoteService: ServiceBase
{
private QuoteServer quoteServer;
Handler Methods
When the service is stopped, the OnStop() method is called. You should stop the service functionality in
this method:
protected override void OnStop()
{
quoteServer.Stop();
}
In addition to OnStart() and OnStop(), you can override the following handlers in the service class:
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OnPause() is called when the service should be paused.
OnContinue() is called when the service should return to normal operation after being paused.
To make it possible for the overridden methods OnPause() and OnContinue() to be called, the
CanPauseAndContinue property must be set to true.
OnShutdown() is called when Windows is undergoing system shutdown. Normally, the behavior
of this method should be similar to the OnStop() implementation; if more time is needed for a
shutdown, you can request additional time. Similarly to OnPause() and OnContinue(), a property
must be set to enable this behavior: CanShutdown must be set to true.
OnPowerEvent() is called when the power status of the system changes. The information
about the change of the power status is in the argument of type PowerBroadcastStatus.
PowerBroadcastStatus is an enumeration with values such as Battery Low and
PowerStatusChange. Here, you will also get information if the system would like to suspend
(QuerySuspend), where you can approve or deny the suspend. You can read more about power events
later in this chapter.
OnCustomCommand() is a handler that can serve custom commands that are sent by a service
control program. The method signature of OnCustomCommand() has an int argument where you
get the custom command number. The value can be in the range from 128 to 256; values below
128 are system-reserved values. In your service, you are re-reading the quotes file with the custom
command 128:
protected override void OnPause()
{
quoteServer.Suspend();
}
protected override void OnContinue()
{
quoteServer.Resume();
}
public const int commandRefresh = 128;
protected override void OnCustomCommand(int command)
{
switch (command)
{
case commandRefresh:
quoteServer.RefreshQuotes();
break;
default:
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