Differences Between a Service and a Device Driver

• Microsoft Windows NT operating system, version 3.1
• Microsoft Windows NT Advanced Server, version 3.1

In the Windows NT operating system, a service and a device driver have different functions. A service is a user-mode process that implements the Service Controller Specification. A device driver is a portion of kernel-mode code that implements the Windows NT Driver Model Specification.

There are some similarities between services and device drivers. The Service Controller is the component of the system that controls starting, pausing, stopping, and continuing services in the system. It also starts and stops (loads and unloads) device drivers. The Service Controller provides a common user interface and application programming interface (API) for services and device drivers.

In some cases, a service is implemented as a front end for a driver. The Workstation service, for example, is implemented as a service from the perspective of the Service Controller. However, the service controls the network redirector file system driver by translating the control codes from the Service Controller into FSCTL (file system control codes) and passing them to the redirector.

Note that the Service Controller can control services and device drivers and it provides an API through which applications can perform the same tasks.