inter-process communication (IPC)

In computing, inter-process communication (IPC) is a set of methods for the exchange of data among multiple threads in one or more processes. Processes may be running on one or more computers connected by a network. IPC methods are divided into methods for message passing, synchronization, shared memory, and remote procedure calls (RPC). The method of IPC used may vary based on the bandwidth and latency of communication between the threads, and the type of data being communicated.
There are several reasons for providing an environment that allows process cooperation:

• Information sharing
• Computational speedup
• Modularity
• Convenience
• Privilege separation

IPC may also be referred to as inter-thread communication and inter-application communication.
The combination of IPC with the address space concept is the foundation for address space independence/isolation.^[1]

Contents

• 1 Main IPC methods
• 2 Implementations
• 3 See also
• 4 References
• 5 External links

Main IPC methods

Method	Short Description	Provided by (operating systems or other environments)
File	A record stored on disk that can be accessed by name by any process	Most operating systems
Signal	A system message sent from one process to another, not usually used to store information but instead give commands.	Most operating systems; some systems, such as Win NT subsystem, implement signals in only the C run-time library and provide no support for their use as an IPC method[citation needed]. But other subsystems like the POSIX subsystem provided by default until windows 2000. Then available with interix in XP/2003 then with « windows services for UNIX » (SFU).
Socket	A data stream sent over a network interface, either to a different process on the same computer or to another computer	Most operating systems
Message queue	An anonymous data stream similar to the pipe, but stores and retrieves information in packets.	Most operating systems
Pipe	A two-way data stream interfaced through standard input and output and is read character by character.	All POSIX systems, Windows
Named pipe	A pipe implemented through a file on the file system instead of standard input and output.	All POSIX systems, Windows
Semaphore	A simple structure that synchronizes threads or processes acting on shared resources.	All POSIX systems, Windows
Shared memory	Multiple processes given access to the same memory, allowing all to change it and read changes made by other processes.	All POSIX systems, Windows
Message passing (shared nothing)	Similar to the message queue.	Used in MPI paradigm, Java RMI, CORBA, DDS, MSMQ, MailSlots, QNX, others
Memory-mapped file	A file mapped to RAM and can be modified by changing memory addresses directly instead of outputting to a stream, shares same benefits as a standard file.	All POSIX systems, Windows

Implementations

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There are several APIs which may be used for IPC. A number of platform independent APIs include the following:

• Anonymous pipes and named pipes
• Common Object Request Broker Architecture (CORBA)
• Freedesktop.org's D-Bus
• Distributed Computing Environment (DCE)
• Message Bus (Mbus) (specified in RFC 3259)
• MCAPI Multicore Communications API
• Lightweight Communications and Marshalling (LCM)
• ONC RPC
• Unix domain sockets
• XML XML-RPC or SOAP
• JSON JSON-RPC
• Thrift
• TIPC
• ZeroC's Internet Communications Engine (ICE)
• ØMQ

The following are platform or programming language specific APIs:

• Apple Computer's Apple events (previously known as Interapplication Communications (IAC)).
• Enea's LINX for Linux (open source) and various DSP and general purpose processors under OSE
• IPC implementation from CMU.
• Java's Remote Method Invocation (RMI)
• KDE's Desktop Communications Protocol (DCOP) - Now deprecated. D-Bus is used instead.
• Libt2n for C++ under Linux only, handles complex objects and exceptions
• The Mach kernel's Mach Ports
• Microsoft's ActiveX, Component Object Model (COM), Microsoft Transaction Server (COM+), Distributed Component Object Model (DCOM), Dynamic Data Exchange (DDE), Object Linking and Embedding (OLE), anonymous pipes, named pipes, Local Procedure Call, MailSlots, Message loop, MSRPC, .NET Remoting, and Windows Communication Foundation (WCF)
• Novell's SPX
• PHP's sessions
• POSIX mmap, message queues, semaphores, and shared memory
• RISC OS's messages
• Solaris Doors
• System V's message queues, semaphores, and shared memory
• Distributed Ruby
• DIPC Distributed Inter-Process Communication
• OpenBinder Open binder
• IPC Shared Memory Messaging from Solace Systems
• QNX's PPS (Persistant Publish/Subscribe) service
• SIMPL The Synchronous Interprocess Messaging Project for Linux (SIMPL)

http://gengwg.blogspot.com/