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For messages longer than 256 bytes a shared memory section must be used to transfer data, which the (A)LPC service maps between the sending and receiving processes. First the sender places data into the shared memory, and then sends a notification (e.g. a small message, using the first method of
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instead of synchronous request/reply mechanism that LPC exclusively uses. This enables ALPC ports high-speed communication which automatically balances the number of messages and threads. Additionally, ALPC messages can be batched together so as to minimize user-mode/kernel-mode switches.
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to use them) and allow identification of the process on the other side of the connection. Individual messages are also securable: applications can set per-message SIDs, and also test for changes of the security context in the token associated with the (A)LPC message.
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As mentioned, Microsoft RPC can use (A)LPC as a transport when the client and server are both on the same machine. Many services that are designed to communicate only on the local computer use (A)LPC as the only transport through RPC. The implementation of remote
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The client receives a handle to the client communication port, and server receives a handle to the server communication port, and the inter-process communication channel is established.
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Server can directly read and write data from the client's address space, when the amount of data is too large to fit in a shared section.
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For short messages (fewer than 256 bytes) the kernel copies the message buffers between processes, from the
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of the sending process to the system address space, and from there to the receiving process' address space.
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85:(UMDF), whose user-mode parts require an efficient communication channel with UMDF's components in the
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81:) in order to provide a high-speed scalable communication mechanism required to efficiently implement
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158:- used by the server to communicate with a particular client; one such port per client is created
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ALPC has a performance advantage over the former LPC interface, as it can be configured to use
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167:(A)LPC supports the following three modes of message exchange between the server and client:
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179:(A)LPC) to the receiving process pointing to the sent data in the shared memory section.
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The typical communication scenario between the server and the client is as follows:
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A client requests a connection to that named port by sending a connect message.
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API to communicate locally, i.e. between the processes on the same machine
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all use (A)LPC ports directly to communicate with client processes.
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by calling
Windows APIs that are implemented with (A)LPC (see below)
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in many cases uses (A)LPC for local communication as well.
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The (A)LPC interface is part of
Windows NT's undocumented
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Dabak, Prasad; Borate, Milind; Phadke, Sandeep (1999),
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276:"LPC (Local procedure calls) Part 1 architecture"
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226:use it to communicate with the LSASS process.
71:Asynchronous Local Inter-Process Communication
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208:Local Security Authority Subsystem Service
142:If the server accepts the connection, two
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360:; Solomon, David; Ionescu, Alex (2009),
319:Russinovich, Solomon & Ionescu (2009
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295:Russinovich, Solomon & Ionescu (2009
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29:Local Inter-Process Communication
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79:Advanced Local Procedure Call
134:named server connection port
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65:on the same computer. As of
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419:Inter-process communication
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45:inter-process communication
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224:Security Reference Monitor
83:User-Mode Driver Framework
41:Lightweight Procedure Call
156:server communication port
150:client communication port
47:facility provided by the
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337:Undocumented Windows NT
216:Service Control Manager
253:Remote procedure call
389:Local Procedure Call
188:I/O completion ports
37:Local Procedure Call
18:Local Procedure Call
146:ports are created:
362:Windows® Internals
399:LPC Communication
375:978-0-7356-2530-3
358:Russinovich, Mark
16:(Redirected from
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364:(5th ed.),
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195:Known usage
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329:References
94:Native API
52:Windows NT
210:(LSASS),
87:executive
63:processes
49:Microsoft
242:See also
222:and the
220:Winlogon
61:between
391:at the
144:unnamed
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55:kernel
321::204)
309::203)
297::201)
259:Notes
248:Doors
201:CSRSS
370:ISBN
345:ISBN
236:DCOM
234:and
206:The
122:SIDs
118:ACLs
75:ALPC
27:The
232:OLE
59:IPC
39:or
33:LPC
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267:^
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73:(
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