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Network Programming

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Tutorial /

Unix Network Programming - RPC Programming

Overview: This tutorial is concerned with building a simple remote application using SUN RPC. You are required to practice what you learned about RPC programming in previous lecture.

Introduction

The remote application to be built is a simple prime number query that provides three basic functions:
isprime (the input number is prime or not),
largestprime (the largest prime number within the search limit), and
totalprime (total number of prime numbers within the search limit).
  • The following shows you a source code of that program which the three functions are performed locally.
#include <stdio.h>
#include <math.h>

#define PRINT_HR {printf("================================================\n");}

int isprime(int n) {
  int i,squareroot;
  if ((n%2)==0) return 0;
  if (n>10) {
   squareroot = (int) sqrt(n);
   for (i=3; i<=squareroot; i=i+2)
      if ((n%i)==0)
         return 0;
   return 1;
   } /* Assume first four primes are counted elsewhere. */
  else
   return 0;
}

int largestprime(int limit) {
  int n; /* loop count */
  int prime; /* most recent prime found */
  for (n=11; n<=limit; n=n+2)
     if (isprime(n)) prime = n;
  return prime;
}

int totalprime(int limit) {
  int n; /* loop count */
  int pc; /* number of prime number */
  pc=4; /* Assume the primes less than 10 (2,3,5,7) are counted here */
  for (n=11; n<=limit; n=n+2)
   if (isprime(n)) pc++;
  return pc;
}

int main(void) {
  long input, result;
  char choice[10];

  while(1) {
    printf("\nPrime Number Information:\n");
    printf("Please select one of the following functions:\n");
    printf("1. The greatest prime number\n");
    printf("2. Number of prime numbers\n");
    printf("3. Is it prime?\n");
    printf("4. Exit\n\n");
    printf("Enter your choice: ");
    scanf("%s", choice);

    switch (atoi(choice)) {

      case 1:
      printf("Enter the limit for your search: ");
      scanf("%d", &input);
      result = largestprime(input);
      PRINT_HR;
      printf("The largest prime number (before %d) is %d\n", input, result);
      PRINT_HR;
      break;

      case 2:
      printf("Enter the limit for your search: ");
      scanf("%d", &input);
      result = totalprime(input);
      PRINT_HR;
      printf("Number of prime numbers (from 1 to %d) is %d\n", input, result);
      PRINT_HR;
      break;

      case 3:
      printf("Enter the integer to be determined: ");
      scanf("%d", &input);
      PRINT_HR;
      if (isprime(input)) {
          printf("Yes, %d is prime.\n", input);
      }
      else
          printf("No, %d is not prime.\n", input);
      PRINT_HR;
      break;

      case 4:
      break;
    }
    if (atoi(choice) == 4) break;
  }
  printf("Program terminated.\n");
  exit(0);
}
[Get Code]
  • In this tutorial, you will be asked to convert the above simple program into a RPC version such that the aforementioned functions are performed remotely by a server program.
  • Specifically, you are required to write a client program that calls remote services using RPC. The client program passes an integer value to a remote server, and the server returns the result value.
  • The server program provides the three prime number query functions.
  • In addition, you will be asked to define the RPC specification file for this application, as well as the steps involved in building the client executable and the server executable.

Activity 1

  • Write a RPC specification file, named pquery.x, to define the server procedures along with their arguments and results. Name the three concerned procedures to be ISPRIME, LARGESTPRIME and TOTALPRIME, respectively.
  • Use rpcgen to compile pquery.x 
        rpcgen pquery.x

Activity 2

  • Study the RPC server program, named pquery_proc.c, which provides the three functions: isprime, largestprime and totalprime.
/*
 * pquery_proc.c - remote procedures; called by server stub.
 */

#include <math.h>
#include <rpc/rpc.h>/* standard RPC include file */
#include "pquery.h"/* this file is generated by rpcgen */

int *
isprime_1(n)
int *n;
{
   int i, squareroot;
   static int result_value;/* return value */

   if ((*n == 2)||(*n == 3)||(*n == 5)||(*n == 7)) {
      result_value = 1;
      return &result_value;
   }

   if ((*n%2) == 0) {
      result_value = 0;
      return &result_value;
   }

   if (*n > 10) {
      squareroot = sqrt((float)*n);
      for (i = 3; i <= squareroot; i = i+2)
         if ((*n%i) == 0) {
            result_value = 0;
            return &result_value;
         }
      result_value = 1;
      return &result_value;
   } else {
      result_value = 0;
      return &result_value;
   }
}

int *
largestprime_1(limit)
int *limit;
{
   int n; /* loop count */
   int *fresult;/* function return result */
   static int result_value;/* largest prime number */

   result_value = 0;
   if (*limit >= 2)
      result_value = 2;
   if (*limit >= 3)
      result_value = 3;
   if (*limit >= 5)
      result_value = 5;
   if (*limit >= 7)
      result_value = 7;

   for (n = 11; n <= *limit;n = n+2) {
      fresult = isprime_1(&n);
      if (*fresult)
         result_value = n;
   }

   return(&result_value);
}

int *
totalprime_1(limit)
int *limit;
{
   int n; /* loop count */
   int *fresult;/* function return result */
   static int result_value;/* number of prime number */

   result_value = 0;
   if (*limit >= 2)
      result_value++;
   if (*limit >= 3)
      result_value++;
   if (*limit >= 5)
      result_value++;
   if (*limit >= 7)
      result_value++;

   for (n = 11; n <= *limit; n = n+2) {
      fresult = isprime_1(&n);
      if (*fresult)
         result_value++;
   }
   return(&result_value);
}
[Get Code]
  • Compile the RPC server program with the following commands: 
        cc –c pquery_proc.c pquery_proc.o
        cc –c pquery_svc.c pquery_svc.o
        cc –o server_pquery pquery_proc.o pquery_svc.o –lrpc -lm

Activity 3

  • Based on the given source code of the program, write a RPC client program where the query functions are performed and returned by the RPC server program.
  • The following program skeleton may be useful to you:
#include <stdio.h>
#include <rpc/rpc.h>
#include "pquery.h"

#define PRINT_HR {printf("================================================\n");}

main(argc, argv)
int   argc;
char  *argv[];
{
   CLIENT *cl;
   int input;
   int *fresult;
   char choice[10];
   char *server;

   if (argc !=2) {
      fprintf(stderr, "usage: %s <hostname of server>\n", argv[0]);
      exit(1);
   }
   server = argv[1];

   // create the client handle

   // call the RPC accordingly

   printf("Program terminated.\n");
   clnt_destroy(cl);
   exit(0);
}
[Get Code]
  • Compile the RPC client program with the following commands: 
        cc –c client_pquery.c client_pquery.o
        cc –c pquery_clnt.c pquery_clnt.o
        cc –o client_pquery client_pquery.o pquery_clnt.o -lrpc

Activity 4

  • Run and test the RPC system with the following commands: 
        ./server_pquery &
        ./client_pquery localhost

Submission

  • You need to demonstrate your work to Steven in a tutorial session. Steven may ask you some questions to test your knowledge.
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Page last modified on December 09, 2009, at 05:27 PM