A Windows service is a background process that performs a speciﬁc operation. Services can run whether or not a user is logged on. Unlike applications, services do not run in visible windows. Services enable the system to perform functions that are not included in the operating system kernel. This keeps the kernel small and streamlined, and it enables an administrator to optimize the performance of the system by running only necessary services.
Figure: Windows services.
Services and Daemons
Windows services are equivalent to daemons on UNIX or Linux systems. Some UNIX daemons are supported on Windows or other operating systems; for example, Windows can run the Line Printer Daemon (LPD) that provides print services on a UNIX server.
Windows Service Startup Values
Based on the conﬁguration you select when you install Windows XP or Windows 7, Setup automatically conﬁgures a core set of its services to automatically start whenever the computer boots. In addition, if you install other Windows features and some third- party software, you will ﬁnd that these applications add their own services to the operating system. You can manage the services in Windows XP or Windows 7 by setting their startup values.
Service Startup Type
Automatic : Start automatically when Windows boots.
Manual : Start manually. In some instances, Windows starts these services for you when you perform an action that requires the service. In other instances, you must open the Services console and manually start the service.
Disabled : Not start under any circumstances. In order to start this service, you must change its startup type to either Automatic or Manual and then start it.
Windows XP and Windows 7 also enable you to conﬁgure the operating system to attempt to automatically restart a service when it fails. You can do so by using the Recovery tab in the Properties dialog box for each service.
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