John Davidson

Message:

We have built a prototype application in PHP and JS using Server-Sent Events (single AJAX requests, multiple streamed events sent by event handlers in PHP). Essentially the PHP at some point is using echo to send data back, much like this example: https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events#sending_events_from_the_server i.e.

echo "event: ping\n";

However the platform we are building for (Magento) has strict coding standards that prohibit echo and print (and print_r and var_dump). Is there any way around this aside from scrapping SSE and setting up AJAX polling?

---

My Answer:
To send Server-Sent Events in PHP without using echo or print, you can use the `header()` function to set the appropriate headers for the SSE response. Here's an example of how you can achieve this:

php

// Set the appropriate headers for Server-Sent Events
header('Content-Type: text/event-stream');
header('Cache-Control: no-cache');

// Function to send a message as an SSE event
function sendSSEMessage($data) {
echo "data: " . json_encode($data) . "\n\n";
ob_flush();
flush();
}

// Send multiple events using the sendSSEMessage function
sendSSEMessage(array('message' => 'Event 1'));
sleep(1); // Simulate delay
sendSSEMessage(array('message' => 'Event 2'));
sleep(1); // Simulate delay
sendSSEMessage(array('message' => 'Event 3'));

?>


In this example, we first set the headers for Server-Sent Events using the `header()` function. Then, we define a function `sendSSEMessage()` that takes data as input, encodes it as JSON, and sends it as an SSE event using `echo`. We also use `ob_flush()` and `flush()` to ensure that the output is sent immediately to the client.

You can call the `sendSSEMessage()` function multiple times to send multiple events to the client. Remember to add delays between events if needed to simulate real-time updates.

This approach allows you to send Server-Sent Events in PHP without using `echo` or `print` directly in the code.