Reading Server Side Events in Python using sseclient - php

Question

I'm new to Server Side Events and started some tests with PHP on the server side and Python on the client side using the sseclient library.
Using a very basic PHP script, based on the w3schools tutorial I can see the data being received in Python:
<?php
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();
}
$time = date('r');
// echo "data: The server time is: {$time}\n\n";
// flush();
sendMsg(time(),"The server time is: {$time}\n\n");
?>
and in Python:
#!/usr/bin/env python
from sseclient import SSEClient
messages = SSEClient('http://pathto/myscript.php')
for msg in messages:
print msg
As a second step I've tried sending data read from an array stored in the $_SESSION variable. This seems to work when I connect to the SSE stream from javascript in the browser, but it doesn't work and I'm not sure why.
Here's my basic PHP script:
<?php
session_start();
header('Content-Type: text/event-stream');
header('Cache-Control: no-cache');
function sendMsg($id, $msg) {
echo "id: $id" . PHP_EOL;
echo "data: $msg" . PHP_EOL;
echo PHP_EOL;
ob_flush();
flush();
}
// check for session data
if (isset($_SESSION["data"])){
#as long there are elements in the data array, stream one at a time, clearing the array (FIFO)
while(count($_SESSION["data"]) > 0){
$serverTime = time();
$data = array_shift($_SESSION["data"]);
sendMsg($serverTime,$data);
}
}
?>
and the Python script is the same.
Why isn't the sseclient Python script picking up the events from the above PHP script (while a basic JS one does) ?

Answer 1

The PHP session variable is sent as a cookie; if you view your JavaScript version with Firebug (or equivalent) you should see the cookie being sent to the SSE server script.
So you'll need to set up a session for the Python script, and have it send that in a cookie too.
You could confirm this guess by adding some error handling to your PHP script:
...
if (isset($_SESSION["data"])){
//current code here
}else{
sendMsg(time(), "Error: no session");
}