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The capacity of an operating system that allows one processto communicate with another process is known as interprocess

communication.One process to another process is running simlatanously

on one or more computer.

IPC enables controlling and sharing of data between severalapplication without interferying with one another.

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TECHNIC OF IPC1. Shared memory technic

2. Message passing technic

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1. SHARED MEMORY TECNIQUE Interprocess communication using shared memory

requires communicating process to establish a regionof shared memory.

Shared memory requires that two or more processesagree to remove this restriction.

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Typically, a shared memory region resides in theaddress space of the process creating the sharedmemory segment.

Other processes that wish to communicate using thisshared memory segment must attach it to theiraddress space.

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2. MESSAGE PASSING TECNIQUE: In message passing technic the communication take

place by means of message exchange betweencooperating process.

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A message passing facility provides at least twooperation : Send(message) and Receive(message).

Message sent by a process can be of either fixed orvariable size.

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If only fixed sized message can be sent, the system-level implementation is straightforward.

This restriction, however, makes the task ofprogramming more difficult.

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Here are several methods for logically implementing alink and the send() / receive() operation.

Direct or indirect communication Synchronous or asynchronous communication

Automatic or explicit buffering

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Direct or indirect communication :

Under direct communication, each process that wants

to communicateMust explicity name the recipient or sender of thecommunication.

In this scheme, the send() and receive() primitives are

defined as: send(P, message)- send a message to process P.

receive(Q, message)- receive a message from process Q.

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With indirect communication, the message are sentto and received from mailboxes, or ports.

Each mailbox has a unique identification. send(A, message)- send a message to mailbox A.

receive(A, message)- receive a message from mailbox A.

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Synchronization or asynchronous:

Communication between processes takes place through

calls to send() and receive() primitives.

message passing may be either blocking or nonblocking

also known as synchronous and asynchronous.

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Blocking send : The sending process is blocked untilthe message is received by the receiving process or bythe mailbox.

Nonblocking send : The sending process sends themessage and resumes operation.

Blocking receive : The receive blocks until a message is

available. Nonblocking receive : The receive retrieves either a

valid message or a null.

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Automatic or explicit buffering:

Whether communication is direct or indirect,

messages exchanged by communicating processesreside in a temporary queue.

Basically, such queues can be implemented in threeways:

Zero capacity buffer Bounded capacity buffer

Unbounded capacity buffer