Inter-process communication

Last Blog Review →

In the last blog we understood, what is a trap command. Why we use the trap command. The syntax of the trap command. And the real-world example of the trap command.

Today’s Agenda → Learning why Inter-process communication is important.

What is inter-process communication ?

1. We understood what is process i.e. a running program with its own memory space, own execution state. So, this process are isolated from each other.

2. Inter-process communication is a set of kernel-provided mechanisms that allow process to exchange data, signal events, sync execution.

3. In short, Inter-process communication is a controlled data exchange between independent processes via. the operating system.

Why inter-process communication is required ?

1. We know that for processes, direct memory sharing is not allowed due to following reasons:

   A. To prevent security breach

   B. Crash propagation

   C. Undefined behavior

2. The core problem IPC solves - IPC provides controlled sharing :

   A. Kerner-approved

   B. Permission checked

   C. Synchronization aware

IPC real world examples

1. Shell Pipeline

    ps aux | grep root
   

   What happens internally:

   1. Shell forks two processes

   2. Kernel creates a pipe

   3. ps writes output to pipe

   4. grep reads input from pipe

Without IPC:

• grep cannot access ps output

• Pipeline concept fails entirely

📌 IPC enables producer–consumer models

2. IPC is required for client-server architecture

   Database Server (PostgreSQL)

   Architecture:

   • One server process

   • Many client processes

Clients need to:

• Send SQL queries

• Receive results

They use:

• UNIX domain sockets

• Or TCP sockets

Without IPC:

• Each client would need its own DB engine

• No centralized data consistency

• Massive resource duplication

➡️ IPC enables service-oriented design

Multiple ways to do IPC -

1. Named pipes : These allow processes to read from and write into it.

2. Shared memory : This is created by one process and is further available for read from and write to this memory by multiple processes.

3. Message queue : This is a structured and an ordered list of memory segments where processes store or retrieve data in queue fashion.

4. Semaphores : This provides a synchronizing mechanism for processes that are accessing the same resource. It has counters that are used to control the access to shared resources by multiple processes.

Conclusion →

In this blog we understood, what is inter-process communication, why inter-process communication. Some real-time examples of it.