Inter-process communication (IPC) refers to the mechanisms and techniques used for exchanging data and synchronizing actions between processes. In this article, we’ll see some IPC methods and their usage in different programming languages.

Pipes

Pipes are a unidirectional communication channel between processes. They allow one process to write data to the pipe, while another process reads from it. Pipes are commonly used for streaming data between processes.

Here’s an example of using pipes in Golang:

// Create a pipe
r, w, _ := os.Pipe()

// Write to the pipe in a goroutine
go func() {
    defer w.Close()
    fmt.Fprint(w, "Hello, pipe!")
}()

// Read from the pipe
var buf bytes.Buffer
io.Copy(&buf, r)
fmt.Println(buf.String())

Named Pipes (FIFOs)

Named pipes, also known as FIFOs (First In, First Out), are similar to regular pipes but have a name associated with them. They exist as a file in the file system and can be accessed by multiple processes.

Here’s an example of using named pipes in Java:

// Create a named pipe
Path path = Paths.get("myfifo");
Files.createNamedPipe(path, PipeOptions.WRITE);

// Write to the named pipe
try (OutputStream os = Files.newOutputStream(path)) {
    os.write("Hello, named pipe!".getBytes());
}

Message Queues

Message queues provide a way for processes to exchange messages asynchronously. Processes can send messages to a queue, and other processes can retrieve those messages from the queue.

Here’s an example of using message queues in Rust with the mio crate:

use mio::{Events, Poll, Token, Waker};
use std::sync::mpsc::{channel, Sender};

fn main() {
    let (tx, rx) = channel();
    let waker = Waker::new(Poll::new().unwrap(), Token(0)).unwrap();

    // Send messages to the queue
    tx.send("Message 1".to_string()).unwrap();
    tx.send("Message 2".to_string()).unwrap();

    // Retrieve messages from the queue
    while let Ok(msg) = rx.try_recv() {
        println!("Received: {}", msg);
    }
}

Shared Memory

Shared memory allows multiple processes to access the same memory region, enabling them to exchange data directly. Processes can read from and write to the shared memory region.

Here’s an example of using shared memory in Golang:

import "golang.org/x/sys/unix"

// Create a shared memory region
shmSize := 1024
shmId, _ := unix.SysvShmGet(0, shmSize, unix.IPC_CREAT|0666)
shmAddr, _ := unix.SysvShmAttach(shmId, 0, 0)
defer unix.SysvShmDetach(shmAddr)

// Write to the shared memory
message := []byte("Hello, shared memory!")
copy(unix.ByteSliceFromString(shmAddr), message)

// Read from the shared memory
data := make([]byte, shmSize)
copy(data, unix.ByteSliceFromString(shmAddr))
fmt.Println(string(data))

Sockets

Sockets provide a communication endpoint for processes to exchange data over a network. They can be used for inter-process communication on the same machine or across different machines.

Here’s an example of using sockets in Java:

// Create a server socket
ServerSocket serverSocket = new ServerSocket(1234);
Socket clientSocket = serverSocket.accept();

// Send data to the client
OutputStream output = clientSocket.getOutputStream();
PrintWriter writer = new PrintWriter(output, true);
writer.println("Hello, socket!");

// Receive data from the client
InputStream input = clientSocket.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(input));
String message = reader.readLine();
System.out.println("Received: " + message);

Signals

Signals are a form of IPC used for sending notifications or interrupts to processes. Processes can send signals to other processes to trigger specific actions or signal events.

Here’s an example of handling signals in Rust:

use std::sync::atomic::{AtomicBool, Ordering};

static RUNNING: AtomicBool = AtomicBool::new(true);

fn main() {
    // Set up signal handler
    ctrlc::set_handler(|| {
        RUNNING.store(false, Ordering::SeqCst);
    }).unwrap();

    // Run the main loop until the signal is received
    while RUNNING.load(Ordering::SeqCst) {
        // Perform some work
    }

    println!("Received signal, exiting...");
}