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ServiceBase Class

Provides a base class for a service that will exist as part of a service application. ServiceBase must be derived when creating a new service class.

For a list of all members of this type, see ServiceBase Members.


[Visual Basic]
Public Class ServiceBase
   Inherits Component
public class ServiceBase : Component
public __gc class ServiceBase : public Component
public class ServiceBase extends Component

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.


Derive from ServiceBase when defining your service class in a service application. Any useful service overrides the OnStart and OnStop methods. For additional functionality, you can override OnPause and OnContinue with specific behavior in response to changes in the service state.

A service is a long-running executable that does not support a user interface, and which might not run under the logged-on user account. The service can run without any user being logged on to the computer.

By default, services run under the System account, which is not the same as the Administrator account. You cannot change the rights of the System account. Alternatively, you can use a ServiceProcessInstaller to specify a user account under which the service will run.

An executable can contain more than one service but must contain a separate ServiceInstaller for each service. The ServiceInstaller instance registers the service with the system. The installer also associates each service with an event log that you can use to record service commands. The main() function in the executable defines which services should run. The current working directory of the service is the system directory, not the directory in which the executable is located.

When you start a service, the system locates the executable and runs the OnStart method for that service, contained within the executable. However, running the service is not the same as running the executable. The executable only loads the service. The service is accessed (for example, started and stopped) through the Service Control Manager.

The executable calls the ServiceBase derived class's constructor the first time you call Start on the service. The OnStart command-handling method is called immediately after the constructor executes. The constructor is not executed again after the first time the service has been loaded, so it is necessary to separate the processing performed by the constructor from that performed by OnStart. Any resources that can be released by OnStop should be created in OnStart. Creating resources in the constructor prevents them from being created properly if the service is started again after OnStop has released the resources.

The Service Control Manager (SCM) provides a way to interact with the service. You can use the SCM to pass Start, Stop, Pause, Continue, or custom commands into the service. The SCM uses the values of CanStop and CanPauseAndContinue to determine whether the service accepts Stop, Pause, or Continue commands. Stop, Pause, and Continue are enabled in the SCM's context menus only if the corresponding property CanStop or CanPauseAndContinue is true in the service class. If enabled, the command is passed to the service, and OnStop, OnPause, or OnContinue are called. If CanStop, CanShutdown, or CanPauseAndContinue is false, the corresponding command-handling method (such as OnStop) will not be processed, even if you have implemented the method.

You can use the ServiceController class to do programmatically what the SCM does using a user interface. You can automate the tasks available in the console. If CanStop, CanShutdown, or CanPauseAndContinue is true but you have not implemented a corresponding command-handling method (such as OnStop) the system throws an exception and ignores the command.

You do not have to implement OnStart, OnStop, or any other method in ServiceBase. However, the service's behavior is described in OnStart, so at minimum, this member should be overridden. You must set the service name of the service in the main() function of the executable. The service name that you set in main() must exactly match the ServiceName property of the service installer.

You can use InstallUtil.exe to install services on your system.

Note   You can specify a log other than the Application event log to receive notification of service calls, but neither the AutoLog nor the EventLog property can write to a custom log. Set AutoLog to false if you do not want to use automatic logging.


Namespace: System.ServiceProcess

Platforms: Windows NT Server 4.0, Windows NT Workstation 4.0, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

Assembly: System.Serviceprocess (in System.Serviceprocess.dll)

See Also

ServiceBase Members | System.ServiceProcess Namespace | ServiceProcessInstaller | ServiceInstaller

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