Refers to token ring frames.
1. access control entry
An ACE is an individual entry in an ACL. An ACE contains a SID and describes the access rights a particular user or group of users has to a system resource. The set of all ACEs on an object are used to determine whether an access request to the object is granted. See also security descriptor.
2. advanced computing environment
A consortium of hardware and software companies formed to promote an open computing environment. Windows NT is one of the original ACE operating systems.
An ordered list of ACEs.
The context collection associated with a local transport driver address. An address object is associated with a file object so several clients can open the same address object. The address object implicitly provides the local addressing information for a connection endpoint.
APC (asynchronous procedure call)
An APC is a Kernel-defined control object representing a procedure that is called asynchronously. APCs are thread-context dependent; that is, they are queued to a particular thread for execution.
There are three different kinds of APCs in Windows NT:
1. User APCs ¾ These APCs are used by certain asynchronous Windows NT system services to allow user-mode applications or protected subsystems to synchronize the execution of a thread with the completion of an operation or the occurrence of an event such as a timer’s expiration. User APCs are, by default, disabled. That is, they are queued to the user-mode thread, but they are not executed except at well-defined points in the program. Specifically, they can only be executed when an application or protected subsystem has called a wait service and has enabled alerts to occur, or if it has called the test-alert service.
2. Kernel APCs ¾ These APCs are normal kernel-mode APCs. They are much like a normal user APC except they are executable by default. That is, they are enabled except when the thread is already executing a kernel APC. (Note that a special always kernel preempts these.)
3. Special Kernel APCs ¾ These APCs cannot be blocked except by running at a raised IRQL. They are executed at APC_LEVEL IRQL (see IDT), in kernel mode. These types of APCs are used by the system to force a thread to execute a procedure in the thread’s context. An example of this is I/O completion: the I/O Manager needs to get back into the context of the original requestor of the I/O operation so it can copy buffers, and so forth. In order to do this, the I/O Manager must be able to access the virtual address space of the thread/process, and the most efficient way to complete the operation is to be in the calling thread’s context.