Socket programming in R to receive UDP stream

Question

In Python I am able to write a code for socket programming to receive a Data stream via UDP.

However, how can I have an equivalent code in R to do the same?

import socket, traceback   
host = ''
port = 5555
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)
s.bind((host, port))

counter = 1500
while counter > 0:
    counter -= 1
    try:
    message, address = s.recvfrom(8192)
    message = message.decode() 
    data = message.split(",")
    print(data)


except (KeyboardInterrupt, SystemExit):
    raise
except:
    traceback.print_exc()

In R I tried with below code, which is not successful. I do realize I need to somewhere mention that its is UDP and all, but unable to find those settings.

I need to receive the 'Stream' of Data from a Device. Do I need to have R-server for this?

platform x86_64-pc-linux-gnu
os linux-gnu
version.string R version 3.2.3 (2015-12-10) RStudio Version 1.0.44

server <- function(){
  while(TRUE){
    writeLines("Listening...")
    con <- socketConnection(host="localhost", port = 5555, blocking=TRUE,server=TRUE, open="r+")
    data <- readLines(con, 1)
    print(data)
    close(con)
 }
}

server()

Answer 1

JF,

My sense would be to write your code directly in C / C++ and include in your R program via the

• R Rcpp package.

Using the above approach you can create a package that mimics the python functionality or just wrap the python code inside an RCPP package directly. This last point is covered in the following tutorial

• Call Python from R through RCPP

I hope the above explanation and code example below will help point you in the right direction.

Rcpp code example:

Listener.R

setwd("~/dev/stackoverflow/40896072")

# install.packages("installr")
# require(installr)
# install.Rtools()
# install.packages("Rcpp")
# # Test and Verify
# Rcpp::evalCpp("2+2")

Rcpp::sourceCpp( file = "./listener.cc")

listen()

Listener.cc

/* listener.c - a datagram socket 'server'
 * simply displays message received then dies!
 */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include <Rcpp.h>
using namespace Rcpp;

#define MYPORT 5555 /* the port users connect to */
#define MAXBUFLEN 100

// [[Rcpp::export]]
int listen() {

    int sockfd;
    struct sockaddr_in my_addr; /* info for my addr i.e. server */
    struct sockaddr_in their_addr; /* client's address info */
    socklen_t addr_len;
    ssize_t numbytes;
    char buf[ MAXBUFLEN];

    printf( "Running\n");

    if( (sockfd = socket( AF_INET, SOCK_DGRAM, 0)) == -1) {
        perror( "Listener socket");
        exit( 1);
    }

    memset( &my_addr, 0, sizeof( my_addr)); /* zero struct */
    my_addr.sin_family = AF_INET; /* host byte order ... */
    my_addr.sin_port = htons( MYPORT); /* ... short, network byte order */
    my_addr.sin_addr.s_addr = INADDR_ANY; /* any of server IP addrs */
    if( bind( sockfd, (struct sockaddr *)&my_addr,
             sizeof( struct sockaddr)) == -1) {
        perror( "Listener bind");
        exit( 1);
    }
    addr_len = sizeof( struct sockaddr);

    if( (numbytes = recvfrom( sockfd, buf, MAXBUFLEN - 1, 0,
                             (struct sockaddr *) &their_addr, &addr_len)) == -1) {
        perror( "Listener recvfrom");
        exit( 1);
    }

    printf( "Got packet from %s\n", inet_ntoa( their_addr.sin_addr));
    printf( "Packet is %zd bytes long\n", numbytes);
    buf[ numbytes] = '\0'; /* end of string */
    printf( "Packet contains \"%s\"\n", buf);
    close( sockfd);
    return 0;
}

Client.R

setwd("~/dev/stackoverflow/40896072")

# install.packages("installr")
# require(installr)
# install.Rtools()
# install.packages("Rcpp")
# # Test and Verify
# Rcpp::evalCpp("2+2")

Rcpp::sourceCpp( file = "./client.cc")

client()

Client.cc

/* client.c - a datagram 'client'
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h> /* for gethostbyname() */

//#include <Rcpp.h>
//using namespace Rcpp;

#define PORT 5555 /* server port the client connects to */

// [[Rcpp::export]]
int client()
{
    socklen_t sockfd;
    ssize_t numbytes;
    struct hostent *he;
    struct sockaddr_in their_addr; /* server address info */
    /* resolve server host name or IP address */
    if ( (he = gethostbyname("localhost")) == NULL )
      {
        perror( "Talker gethostbyname");
        exit( 1);
      }

    if ( (sockfd = socket( AF_INET, SOCK_DGRAM, 0)) == -1)
      {
        perror( "Talker socket");
        exit( 1);
      }

    memset( &their_addr,0, sizeof(their_addr) ); /* zero struct */
    their_addr.sin_family = AF_INET; /* host byte order .. */
    their_addr.sin_port = htons( PORT); /* .. short, netwk byte order */
    their_addr.sin_addr = *( (struct in_addr *)he -> h_addr);

    if( (numbytes = sendto( sockfd, "Hello", strlen("Hello"), 0,
                            (struct sockaddr *) &their_addr,
                            sizeof( struct sockaddr))) == -1)
    {
      perror( "Talker sendto");
      exit( 1);
    }

    printf( "Sent %zd bytes to %s\n", numbytes,
            inet_ntoa( their_addr.sin_addr));

    close( sockfd );
    return 0;
}

Runtime output