Windows NT Executive Services

The Windows NT Executive Services consist of a set of common services available to all components of the operating system. Each group of services is managed by one of these separate components of the Executive:

• I/O Manager
• Object Manager
• Security Reference Monitor (which, along with the Logon and Security protected subsystems, makes up the Windows NT security model)
• Process Manager
• Local Procedure Call Facility
• Virtual Memory Manager
• Window Manager
• Graphics Device Interface
• Graphics Device Drivers

The thin top layer of the Executive is called the System Services. The System Services shown in Figure 5.1 (and on the inside back cover of this book) are the interface between user-mode environment subsystems and kernel mode. The following sections describe the role of each Executive component.