I have a C++ program that reads a file and prints it one line at a time (one line per second).
I need the code executed from within a PHP script and the output piped back to a browser. So far, I have tried exec and passthru but in both these cases, the entire output is 'dumped' on the browser after program execution.
How do I get PHP to stream the output back to the browser.
Here is the code I have written so far:
sender.php: Sends the request to execute.
<?php
/*
* Purpose of this program:
* To display a stream of text from another C++-based program.
* Steps:
* 1. Button click starts execution of the C++ program.
* 2. C++ program reads a file line-by-line and prints the output.
*/
?>
<html>
<head>
<script type="text/javascript" src="js/jquery-1.11.2.min.js"></script>
<script type="text/javascript">
$(document).ready(function() {
$("#startDisplaying").click(function() {
console.log("Starting to display.");
/*
//initialize event source.
if(!!window.EventSource) {
console.log("Event source is available.");
var evtSource = new EventSource("receiver.php");
evtSource.addEventListener('message', function(e) {
console.log(e.data);
}, false);
evtSource.addEventListener('open', function(e) {
console.log("Connection opened.");
}, false);
evtSource.addEventListener('error', function(e) {
console.log("Error seen.");
if(e.readyState == EventSource.CLOSED) {
console.log("Connection closed.");
}
}, false);
} else {
console.error("Event source not available.");
}
*/
$.ajax({
type: 'POST',
url: 'receiver.php',
success: function(data) {
console.log("Data obtained on success: " + data);
$("#displayText").text(data);
},
error: function(xhr, textStatus, errorThrown) {
console.error("Error seen: " + textStatus + " and error = " + errorThrown);
}
});
});
});
</script>
</head>
<body>
<textarea id="displayText"></textarea><br/>
<button id="startDisplaying">Start Displaying</button>
</body>
</html>
The receiver.php, which executes the program:
<?php
/* This file receives the request sent by sender.php and processes it.
* Steps:
* 1. Start executing the timedFileReader executable.
* 2. Print the output to the textDisplay textarea.
*/
header('Content-Type: text/event-stream');
header('Cache-control: no-cache');
function sendMsg($id, $msg) {
echo "id: $id".PHP_EOL;
echo "data: $msg".PHP_EOL;
echo PHP_EOL;
ob_flush();
flush();
}
$serverTime = time();
$cmd = "\"timedFileReader.exe\"";
//sendMsg($serverTime, 'server time: '.exec($cmd, time()));
passthru($cmd);
/*
$cmd = "\"timedFileReader.exe\"";
exec($cmd. " 2>&1 ", $output);
print_r($output);
*/
?>
The C++ program:
#include<fstream>
#include<string>
#include<unistd.h>
#include<cstdlib>
#include<iostream>
using namespace std;
int main(int argc, char *argv[]) {
ifstream ifile;
string line;
ifile.open("file.txt");
if(!ifile) {
cout << "Could not open file for reading." << endl;
exit(0);
}
while(getline(ifile, line)) {
cout << line << endl;
//usleep(5000000); //sleep for 1000 microsecs.
sleep(1);
}
return 0;
}
Is this model of execution even possible within PHP?
Any help is most welcome.
