InterProcess Communication

 

Expt No: 4                       Inter–Process Communication

Date:

 

Aim: To develop application to illustrate Inter Process Communication among processes using Shared memory, Pipes and Message Queue.

 

Program :

// 1. IPC Using Shared Memory – Server Program

#include <sys/shm.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

 

#define MAXSIZE 128

 

void die(char *s) {

    perror(s);

    exit(1);

}

 

int main() {

    int shmid;

    key_t key;

    char *shm;

   

    key = 5678;

 

    if ((shmid = shmget(key, MAXSIZE, IPC_CREAT | 0666)) < 0)

        die("shmget");

 

    if ((shm = shmat(shmid, NULL, 0)) == (char *) -1)

        die("shmat");

   

    printf("Enter a message: ");

    fgets(shm, MAXSIZE, stdin);

    shm[strcspn(shm, "\n")] = 0; // Remove newline character

   

    printf("Message written to shared memory.\n");

    exit(0);

}

 

// 1. IPC Using Shared Memory – Client Program

 

#include <sys/shm.h>

#include <stdio.h>

#include <stdlib.h>

 

#define MAXSIZE     27

 

void die(char *s)

{

     perror(s);

     exit(1);

}

 

int main()

{

     int shmid;

     key_t key;

     char *shm, *s;

     key = 5678;

 

     if ((shmid = shmget(key, MAXSIZE, 0666)) < 0)

         die("shmget");

 

     if ((shm = shmat(shmid, NULL, 0)) == (char *) -1)

         die("shmat");

    printf("\nMessage read from shared memory - ");

     for (s = shm; *s != '\0'; s++)

         putchar(*s);

     putchar('\n');

 

     exit(0);

}

 

 

 

// 2. IPC Using Message Queue

// Sender Program

 

#include <sys/msg.h>

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

 

#define MAXSIZE 128

 

struct msgbuf {

    long mtype;

    char mtext[MAXSIZE];

};

 

int main() {

    int msqid;

    key_t key = 1234;

    struct msgbuf sbuf;

    size_t buflen;

 

    if ((msqid = msgget(key, IPC_CREAT | 0666)) < 0) {

        perror("msgget");

        exit(1);

    }

 

    sbuf.mtype = 1;

    printf("Enter a message: ");

    fgets(sbuf.mtext, MAXSIZE, stdin);

    buflen = strlen(sbuf.mtext) + 1;

 

    if (msgsnd(msqid, &sbuf, buflen, IPC_NOWAIT) < 0) {

        perror("msgsnd");

        exit(1);

    }

    printf("Message Sent\n");

    return 0;

}

 

 

// 2. IPC Using Message Queue

// Receiver Program

 

#include <sys/msg.h>

#include <stdio.h>

#include <stdlib.h>

 

#define MSGSZ 128

 

struct msgbuf {

    long mtype;

    char mtext[MSGSZ];

};

 

int main() {

    int msqid;

    key_t key = 1234;

    struct msgbuf rbuf;

 

    if ((msqid = msgget(key, 0666)) < 0) {

        perror("msgget");

        exit(1);

    }

    if (msgrcv(msqid, &rbuf, MSGSZ, 1, 0) < 0) {

        perror("msgrcv");

        exit(1);

    }

 

    printf("Received Message: %s\n", rbuf.mtext);

    return 0;

}

 

 

// 3. IPC Using Pipes

 

#include<stdio.h>

#include<unistd.h>

#include<string.h>

#include<sys/types.h>

#include<sys/wait.h>

 

int main()

{

    int p1[2], p2[2];

    char str[25];

 

    printf("\nIPC USING PIPES\n");

    printf("Enter Message to send : ");

        scanf("%s",str);

 

    pipe(p1);

    pipe(p2);

    write(p1[1],str,sizeof(str));

 

    int a=fork();

    if(a==0)

    {

        printf("\n Child Process :");

        printf("\n Child process pid=%d ", getpid());

        printf("\n Parent process pid=%d ", getppid());

        read(p1[0],str,sizeof(str));

        printf("\n\tMessage received from Parent process : %s\n",str);

        write(p2[1],str,sizeof(str));

    }

    else

    {

        wait(NULL);

        printf("\n Parent Process :");

        printf("\n Parent process pid=%d ", getpid());

        read(p2[0],str,sizeof(str));

        printf("\n\tMessage returned from Child process : %s\n\n",str);

    }

 }

 

 

 

Result: Thus the programs to demonstrate Inter Process Communication among processes using Shared memory, Message Queue and Pipes were written and executed.