Program For Reversing String Using Message Passing Interface (MPI)

1) Program For Server Side 

server.c 

#include <stdlib.h> #include <stdio.h>
#include "mpi.h"
#include<string.h>
int main(int argc, char **argv)
{
MPI_Comm client;
MPI_Status status;
char port_name[MPI_MAX_PORT_NAME],str[50],ch,temp;
int size, again, i,j;
MPI_Init(&argc, &argv);
MPI_Comm_size(MPI_COMM_WORLD, &size);
if (size != 1)
{
fprintf(stderr, "Server too big");
exit(EXIT_FAILURE);
}
MPI_Open_port(MPI_INFO_NULL, port_name);
printf("Server available at port: %s\n", port_name);
i=0;
while (1)
{
MPI_Comm_accept(port_name, MPI_INFO_NULL, 0, MPI_COMM_WORLD, &client);
again = 1;
while (again)
{
MPI_Recv(&ch, 1, MPI_CHAR, MPI_ANY_SOURCE, MPI_ANY_TAG, client, &status);
switch (status.MPI_TAG)
{
case 0:
MPI_Comm_free(&client);
MPI_Close_port(port_name);
MPI_Finalize();
return 0;
case 1:
printf("\nReceived String: %s\n",str);
// reverse the string
i = 0;
j = strlen(str) - 1;
while (i < j)
{
temp = str[i];
str[i] = str[j];
str[j] = temp;
i++;
j--;
}

printf("\nReversed string is : %s\n",str);

// send the reversed string to client (character by character)
for (i = 0; i < strlen(str); i++)
{
ch=str[i];
MPI_Send(&ch, 1, MPI_CHAR, 0, 2, client);
}

//send tag=1 to indicate end of string
MPI_Send(&ch, 1, MPI_CHAR, 0, 1, client);
MPI_Comm_disconnect(&client);
again = 0;
strcpy(str,"");
i=0;
break;
case 2:
printf("Received character: %c\n", ch);
str[i]=ch;
i++;
// add null character at the end of string
str[i]='\0';
break;
default:
/* Unexpected message type */
MPI_Abort(MPI_COMM_WORLD, 1);
}
}
}

}


2) Program For Client Side

client.c

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "mpi.h"

int main( int argc, char **argv )
{
MPI_Comm server;
MPI_Status status;
char port_name[MPI_MAX_PORT_NAME],str[50],ch;
int i, tag,again;
if (argc < 2)
{
fprintf(stderr, "server port name required.\n");
exit(EXIT_FAILURE);
}
MPI_Init(&argc, &argv);
strcpy(port_name, argv[1]);
MPI_Comm_connect(port_name, MPI_INFO_NULL, 0, MPI_COMM_WORLD, &server);

// accept input string
printf("\nEnter the string :\n");
scanf("%s",str);

//send string to server (character by character)
for (i = 0; i < strlen(str); i++)
{
if(str[i]!='\0')
ch=str[i];
tag=2;
MPI_Send(&ch, 1, MPI_CHAR, 0, tag, server);
}

// done sending string to the server
MPI_Send(&i, 0, MPI_INT, 0, 1, server);

// Receive the reversed string from server and display it
i=0;
again=1;
while (again)
{
MPI_Recv(&ch, 1, MPI_CHAR, MPI_ANY_SOURCE, MPI_ANY_TAG, server, &status);
switch (status.MPI_TAG)
{
case 2:
str[i]=ch;
i++;
break;
case 1:
again=0;
break;
}
}

printf("\nReversed string is : %s\n\n",str);
MPI_Comm_disconnect(&server);
MPI_Finalize();
return 0;

}

/* OUTPUT

At Server Side

humble@humble-desktop:~$ cd exp4

humble@humble-desktop:~/exp4$ mpicc server.c -o server

humble@humble-desktop:~/exp4$ mpicc client.c -o client

humble@humble-desktop:~/exp4$ mpirun -np 1 ./server

Received character: H

Received character: u

Received character: m

Received character: b

Received character: l

Received character: e

Received String: Humble

Reversed string is: elbmuH

At Client Side

humble@humble-desktop:~$ cd exp4

humble@humble-desktop:~/exp4$ mpirun -np 1 ./client '2108030976.0;tcp://172.16.219.177:53146+2108030977.0;tcp://172.16.219.177:39924:300'

Enter the string :

Humble

Reversed string is : elbmuH

*/