IPC mechanism

What is IPC?

IPC is a mechanism that involves communication of the one process with another process. This usually occurs only in one system.

Communication can be of 2 types,

Between related processes initiating from only one process, such as parent and child processes.

    Between unrelated processes, or two or more different processes.

How to do IPC?? What are the ways? 

Pipes

Communication between two related processes.

The mechanism is half duplex meaning the first process communicates with the second process. To achieve a full duplex i.e., for the second process to communicate with the first process another pipe is required.

FIFO

Communication between two unrelated processes.

FIFO is a full duplex, meaning the first process can communicate with the second process and vice versa at the same time.

Message Queues

Communication between two or more processes with full duplex capacity.

The processes will communicate with each other by posting a message and retrieving it out of the queue. Once retrieved, the message is no longer available in the queue.

Shared Memory

Communication between two or more processes is achieved through a shared piece of memory among all processes.

The shared memory needs to be protected from each other by synchronizing access to all the processes.

Semaphores − Semaphores are meant for synchronizing access to multiple processes. When one process wants to access the memory (for reading or writing), it needs to be locked (or protected) and released when the access is removed. This needs to be repeated by all the processes to secure data.

Signals

Signal is a mechanism to communication between multiple processes by way of signaling. This means a source process will send a signal (recognized by number) and the destination process will handle it accordingly.