javascript - Server-side event - how to pass parameters to server-side script? Append query string? - Stack Overflow

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I am trying to pass parameters to a PHP script that is used to stream server-side events. I am using Javascript to listen to the events. I have tried to pass parameters by appending a query string to the server-side script url:

Javascript:

var source = new EventSource("demo_sse.php?file=query");

demo_sse.php:

<?php
  header("Content-Type: text/event-stream\n\n");
  echo 'data:'.$_GET["file"]."\n\n";
?> 

I would expect to see "query" displayed, but instead I get no output.

I also tried:

echo 'data:'.$_SERVER['QUERY_STRING']."\n\n";

But still no output. I have verified that the script works otherwise (can print explicit strings).

I haven't found much on the subject, but I did find a couple of examples of appending the query string to the url in the EventSource argument: Server Sent Events Stop Start with new parameter.

I am trying to pass parameters to a PHP script that is used to stream server-side events. I am using Javascript to listen to the events. I have tried to pass parameters by appending a query string to the server-side script url:

Javascript:

var source = new EventSource("demo_sse.php?file=query");

demo_sse.php:

<?php
  header("Content-Type: text/event-stream\n\n");
  echo 'data:'.$_GET["file"]."\n\n";
?> 

I would expect to see "query" displayed, but instead I get no output.

I also tried:

echo 'data:'.$_SERVER['QUERY_STRING']."\n\n";

But still no output. I have verified that the script works otherwise (can print explicit strings).

I haven't found much on the subject, but I did find a couple of examples of appending the query string to the url in the EventSource argument: Server Sent Events Stop Start with new parameter.

• javascript
• php

Share Improve this question Follow edited May 23, 2017 at 11:51 CommunityBot 111 silver badge asked Mar 11, 2014 at 14:41 KevinHJKevinHJ 1,12411 gold badge1111 silver badges2828 bronze badges 4

• What could you need to pass to the server? If you're looking for bidirectional munication, use WebSockets – Ian Commented Mar 11, 2014 at 15:05
• @Ian: SSEs are sent over traditional HTTP. That means they do not require a special protocol or server implementation to get working. WebSockets on the other hand, require full-duplex connections and new Web Socket servers to handle the protocol. In addition, Server-Sent Events have a variety of features that WebSockets lack by design such as automatic reconnection, event IDs, and the ability to send arbitrary events. - quoted from html5rocks./en/tutorials/eventsource/basics - yes, I need to pass data to server to tell script where to find file. – KevinHJ Commented Mar 12, 2014 at 12:52
• @Ian: WebSockets are more plex, and require installing a module on the server. I don't need continual bidi munication, I only want to send a single bit of data upon initiation of the server-side script. WebSockets is overkill for what I need. The query string idea seemed like it ought to work, but I was looking for confirmation. I hope someone can answer the question I asked. – KevinHJ Commented Mar 12, 2014 at 13:17
• why not just ajax a post request? is there something I'm missing here? – Royalty Commented Jun 10, 2015 at 21:16

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1 Answer 1

Sorted by: Reset to default 5

I have tried the following code and SSE seemed to work:

var es = new EventSource('http://localhost/ssed.php?asdf=test111');
es.onmessage=function(e){console.log(e.data);}

ssed.php:

<?php
header("Content-Type: text/event-stream\n\n");
echo 'data:'.$_GET['asdf']."\n\n";

How is your onmessage function written? Is it possible that your browser doesn't support SSE?

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