ServiceBase Class

Definition

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

public class ServiceBase : System.ComponentModel.Component
Inheritance

Remarks

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 is 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. The main() function of the executable registers the service in the executable with the Service Control Manager by calling the Run method. The ServiceName property of the ServiceBase object passed to the Run method must match the ServiceName property of the service installer for that service.

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.

Constructors

ServiceBase()

Creates a new instance of the ServiceBase class.

Fields

MaxNameLength

Indicates the maximum size for a service name.

Properties

AutoLog

Indicates whether to report Start, Stop, Pause, and Continue commands in the event log.

CanHandlePowerEvent

Gets or sets a value indicating whether the service can handle notifications of computer power status changes.

CanHandleSessionChangeEvent

Gets or sets a value that indicates whether the service can handle session change events received from a Terminal Server session.

CanPauseAndContinue

Gets or sets a value indicating whether the service can be paused and resumed.

CanShutdown

Gets or sets a value indicating whether the service should be notified when the system is shutting down.

CanStop

Gets or sets a value indicating whether the service can be stopped once it has started.

EventLog

Gets an event log you can use to write notification of service command calls, such as Start and Stop, to the Application event log.

ExitCode

Gets or sets the exit code for the service.

ServiceHandle

Gets the service control handle for the service.

ServiceName

Gets or sets the short name used to identify the service to the system.

Methods

Dispose(Boolean)

Disposes of the resources (other than memory) used by the ServiceBase.

OnContinue()

When implemented in a derived class, OnContinue() runs when a Continue command is sent to the service by the Service Control Manager (SCM). Specifies actions to take when a service resumes normal functioning after being paused.

OnCustomCommand(Int32)

When implemented in a derived class, OnCustomCommand(Int32) executes when the Service Control Manager (SCM) passes a custom command to the service. Specifies actions to take when a command with the specified parameter value occurs.

OnPause()

When implemented in a derived class, executes when a Pause command is sent to the service by the Service Control Manager (SCM). Specifies actions to take when a service pauses.

OnPowerEvent(PowerBroadcastStatus)

When implemented in a derived class, executes when the computer's power status has changed. This applies to laptop computers when they go into suspended mode, which is not the same as a system shutdown.

OnSessionChange(SessionChangeDescription)

Executes when a change event is received from a Terminal Server session.

OnShutdown()

When implemented in a derived class, executes when the system is shutting down. Specifies what should occur immediately prior to the system shutting down.

OnStart(String[])

When implemented in a derived class, executes when a Start command is sent to the service by the Service Control Manager (SCM) or when the operating system starts (for a service that starts automatically). Specifies actions to take when the service starts.

OnStop()

When implemented in a derived class, executes when a Stop command is sent to the service by the Service Control Manager (SCM). Specifies actions to take when a service stops running.

RequestAdditionalTime(Int32)

Requests additional time for a pending operation.

Run(ServiceBase)

Registers the executable for a service with the Service Control Manager (SCM).

Run(ServiceBase[])

Registers the executable for multiple services with the Service Control Manager (SCM).

ServiceMainCallback(Int32, IntPtr)

Registers the command handler and starts the service.

Stop()

Stops the executing service.

CanRaiseEvents Inherited from Component
Container Inherited from Component
DesignMode Inherited from Component
Dispose() Inherited from Component
Disposed Inherited from Component
Events Inherited from Component
GetService(Type) Inherited from Component
Site Inherited from Component
ToString() Inherited from Component
CreateObjRef(Type) Inherited from MarshalByRefObject
GetLifetimeService() Inherited from MarshalByRefObject
InitializeLifetimeService() Inherited from MarshalByRefObject
MemberwiseClone(Boolean) Inherited from MarshalByRefObject
Equals(Object) Inherited from Object
Equals(Object, Object) Inherited from Object
GetHashCode() Inherited from Object
GetType() Inherited from Object
MemberwiseClone() Inherited from Object
ReferenceEquals(Object, Object) Inherited from Object

Applies to