[SOLVED] cURL - Structuring request to validate server sent events

Issue

I am new to cURL and server sent events. I know how to build a simple GET, POST requests using cURL and getting response. Also, theoretically I am aware that server sent events are handled by creating a listener to event source but I am not sure how to proceed with validating any such API with cURL. Any guidance is appreciated.

Solution

SSE is a text-based protocol, and curl is a great way to troubleshoot exactly what your connection is sending. The command is this simple:

curl -N http://127.0.0.1/path/to/clock.php

(The -N stops any buffering, so data is shown as it is received.)

And it outputs this:

data:2015-07-07 06:19:27

data:2015-07-07 06:19:28

data:2015-07-07 06:19:29

data:2015-07-07 06:19:30

data:2015-07-07 06:19:31

data:2015-07-07 06:19:32

Notice how it shows the "data:" prefix of the SSE protocol, and also clearly shows the double LFs. It runs forever, until you press ctrl-c.

About the only thing to point out is that you must use a web server; you cannot run SSE over the file:// protocol.

For more hard-core troubleshooting, add --verbose, which will show the headers being sent, and the headers being received.

SSE does support cookies, which you could give like this: (you would first have to prepare the "cookies.txt" file):

curl -N --cookie cookies.txt http://127.0.0.1/path/to/clock.php

See other answer and the curl documentation for other options you might want to consider using. If you are troubleshooting problems in a specific browser, use their devtools to find out exactly what headers are being sent, and then you can tell curl to do the same.

---

For completeness, here is the clock.php script:

<?php 
set_time_limit(0);
header("Content-type: text/event-stream");

while(1){
    echo "data:" . date("Y-m-d H:i:s") . "\n\n";
    @ob_flush();flush();
    sleep(1);
    }

Answered By - Darren Cook

Answer Checked By - Senaida (WPSolving Volunteer)