[[!meta copyright="Copyright © 2007, 2008, 2010 Free Software Foundation, Inc."]] [[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable id="license" text="Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled [[GNU Free Documentation License|/fdl]]."]]"""]] Read about the [[general concept of *inter-process communication* (IPC)|/ipc]]. On Mach, an IPC is done by invoking a [[port]]. The two fundamental operations, to *send* and *receive* [[message]]s, are used to implement a [[RPC]] system. [[Sequence_numbering]]. [The Unofficial GNU Mach IPC beginner's guide](http://www.nongnu.org/hurdextras/ipc_guide/ipc_guide.html)