Object Manager: Difference between revisions

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Objects can either be ''Kernel objects'' or ''Executive objects''. Kernel objects represent primitive resources such as physical devices, or services such as synchronization, which are required to implement any other type of OS service. Kernel objects are not exposed to [[user mode]] code, but are restricted to kernel code. Applications and services running outside the kernel use ''Executive objects'', which are exposed by the [[Windows Executive]], along with its components such as the memory manager, scheduler and I/O subsystem. Executive objects encapsulate one or more kernel objects and expose not only the kernel and kernel-mediated resources, but also an expanded set of services that the kernel does.{{clarify|date=January 2019}} Applications themselves can wrap one or more Executive objects and surface objects{{Definition needed|date=January 2019}} that offer certain services. Executive objects are also used by the environment subsystems (such as the Win32 subsystem, the OS/2 subsystem, the POSIX subsystem, etc.) to implement the functionality of the respective environments.

Whenever an object is created or opened, a reference to the instance, calledknown as a ''handle'', is created. The Object Manager indexes the objects by both by their names as well as theand handles. But, referencing theReferencing objects by the handles is faster becausesince theit bypasses name translation can be skipped. Handles are associated with processes (by making an entry intoin the process's ''Handle table'', thatwhich lists the handles it owns), and can be transferred between processes as well. A process must own a handle to an object beforeto usinguse it., A processand can own aup maximum ofto 16,000,000 handles at one time. During creation, a process gains handles to a default set of objects. WhileThere there existsare different types of handles, -such as ''file handles'', ''event handles'', and ''process handles'', -which they only help in identifyingidentify the type of the target objects; but do not in distinguishingdistinguish the operations that can be performed through them, thus. providingThis consistency toensures uniform howhandling of various object types are handled programmatically. Handle creation and resolution of objects from handles are solelyexclusively mediatedmanaged by the Object Manager, soensuring that no resource usage goes unnoticed by it.

The types of Executive objects exposed by Windows NT are: