Inter-process communication

An example showing a grid computing system connecting many personal computers over the Internet using inter-process network communication

In computer science, inter-process communication or interprocess communication (IPC) refers specifically to the mechanisms an operating system provides to allow the processes to manage shared data. Typically, applications can use IPC, categorized as clients and servers, where the client requests data and the server responds to client requests.[1] Many applications are both clients and servers, as commonly seen in distributed computing. Methods for achieving IPC are divided into categories which vary based on software requirements, such as performance and modularity requirements, and system circumstances, such as network bandwidth and latency.[1]

IPC is very important to the design process for microkernels and nanokernels. Microkernels reduce the number of functionalities provided by the kernel. Those functionalities are then obtained by communicating with servers via IPC, increasing drastically the number of IPC compared to a regular monolithic kernel.

Approaches

Method Short Description Provided by (operating systems or other environments)
File A record stored on disk, or a record synthesized on demand by a file server, which can be accessed by multiple processes. Most operating systems
Signal; also Asynchronous System Trap A system message sent from one process to another, not usually used to transfer data but instead used to remotely command the partnered process. Most operating systems
Socket A data stream sent over a network interface, either to a different process on the same computer or to another computer on the network. Typically byte-oriented, sockets rarely preserve message boundaries. Data written through a socket requires formatting to preserve message boundaries. Most operating systems
Unix domain socket Similar to an internet socket but all communication occurs within the kernel. Domain sockets use the file system as their address space. Processes reference a domain socket as an inode, and multiple processes can communicate with one socket All POSIX operating systems
Message queue A data stream similar to a socket, but which usually preserves message boundaries. Typically implemented by the operating system, they allow multiple processes to read and write to the message queue without being directly connected to each other. Most operating systems
Pipe A unidirectional data channel. Data written to the write end of the pipe is buffered by the operating system until it is read from the read end of the pipe. Two-way data streams between processes can be achieved by creating two pipes utilizing standard input and output. All POSIX systems, Windows
Named pipe A pipe implemented through a file on the file system instead of standard input and output. Multiple processes can read and write to the file as a buffer for IPC data. All POSIX systems, Windows, AmigaOS 2.0+
Shared memory Multiple processes are given access to the same block of memory which creates a shared buffer for the processes to communicate with each other. All POSIX systems, Windows
Message passing Allows multiple programs to communicate using message queues and/or non-OS managed channels, commonly used in concurrency models. Used in RPC, RMI, and MPI paradigms, 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. This shares the same benefits as a standard file. All POSIX systems, Windows

Synchronization

Depending on solution IPC mechanism may provide synchronization or leave it up to processes and threads communicating (such as shared memory).

While synchronization includes some information (is lock enabled or not, counter of waiters etc.) it is not primarily information passing communication mechanism per se.

Examples of synchronization primitives are:

Applications

Remote procedure call interfaces

Platform communication stack

The following are messaging and information systems that utilize IPC mechanisms, but don't implement IPC themselves:

Operating system communication stack

The following are platform or programming language-specific APIs:


Distributed object models

The following are platform or programming language specific-APIs that use IPC, but do not themselves implement it:

See also

References

  1. 1 2 "Interprocess Communications". Microsoft.
  2. ↑ Concurrent programming - communication between processes http://www.tldp.org/pub/Linux/docs/ldp-archived/linuxfocus/English/Archives/lf-2003_01-0281.pdf
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