Hi,
See: http://www.w3schools.com/HTML/html5_serversentevents.asp
With just native PHP on the server side it’s a no-brainer, but how do I get this running with Slim3?
I need this badly for a project that updates a browser-client every 3 seconds
This is the first time I’ve heard of SSE (yes, my bad) but a first thought would be that if you don’t get a satisfying answer in the time you need, couldn’t the same thing be achieved by calling an Ajax function scheduled through setInterval()?
Maybe this helps, I just wanted to offer this suggestion.
That’s the way I’m doing it right now 
… but It creates a lot of overhead as some intervals are 1 sec. The server is flooded with requests, compared to a simple loop that writest a few bytes every few seconds using SSE.
Presto, I did it. Reworked the CallbackStream in https://github.com/phly/psr7examples and that did the trick.
Javascript snippet
var evtSource = new EventSource(send_url);
evtSource.onmessage = function(event) {
if ( event.data.substr(0,3) == 'END') {
evtSource.close();
} else {
$('#result').html(event.data);
}
};
Controller part (Slim3)
$output = new CallbackStream(function () use ($request) {
for ($i=0; $i<10; $i++) {
$time = date('r');
echo "data: The server time is: {$time}\n\n";
ob_flush();
flush();
sleep(2);
}
echo "data: END\n\n";
ob_flush();
flush();
return '';
});
return (new Response())
->withHeader('Content-Type', 'text/event-stream')
->withHeader('Cache-Control', 'no-cache')
->withBody($output);
CallbackStream helper class
[code]<?php
namespace Helper;
use Psr\Http\Message\StreamInterface;
/**
-
Callback-based stream implementation.
-
Wraps a callback, and invokes it in order to stream it.
-
Only one invocation is allowed; multiple invocations will return an empty
-
string for the second and subsequent calls.
/
class CallbackStream implements StreamInterface
{
/*-
@var callable
*/
private $callback;
/**
- Whether or not the callback has been previously invoked.
-
@var bool
*/
private $called = false;
public function __construct(callable $callback)
{
$this->callback = $callback;
}/**
-
@return string
*/
public function __toString()
{
return $this->output();
}
/**
-
Execute the callback with output buffering.
-
@return null|string Null on second and subsequent calls.
*/
public function output()
{
if ($this->called) {
return;
}$this->called = true;
call_user_func($this->callback);
return;
}
/**
-
@return void
*/
public function close()
{
}
/**
-
@return null|callable
*/
public function detach()
{
$callback = $this->callback;
$this->callback = null;
return $callback;
}
/**
-
@return int|null Returns the size in bytes if known, or null if unknown.
*/
public function getSize()
{
}
/**
-
@return int|bool Position of the file pointer or false on error.
*/
public function tell()
{
return 0;
}
/**
-
@return bool
*/
public function eof()
{
return $this->called;
}
/**
-
@return bool
*/
public function isSeekable()
{
return false;
}
/**
- @link http://www.php.net/manual/en/function.fseek.php
- @param int $offset Stream offset
- @param int $whence Specifies how the cursor position will be calculated
-
based on the seek offset. Valid values are identical to the built-in -
PHP $whence values for `fseek()`. SEEK_SET: Set position equal to -
offset bytes SEEK_CUR: Set position to current location plus offset -
SEEK_END: Set position to end-of-stream plus offset. -
@return bool Returns TRUE on success or FALSE on failure.
*/
public function seek($offset, $whence = SEEK_SET)
{
return false;
}
/**
- @see seek()
- @link http://www.php.net/manual/en/function.fseek.php
-
@return bool Returns TRUE on success or FALSE on failure.
*/
public function rewind()
{
return false;
}
/**
-
@return bool
*/
public function isWritable()
{
return false;
}
/**
- @param string $string The string that is to be written.
- @return int|bool Returns the number of bytes written to the stream on
-
success or FALSE on failure.
*/
public function write($string)
{
return false;
}/**
-
@return bool
*/
public function isReadable()
{
return true;
}
/**
- @param int $length Read up to $length bytes from the object and return
-
them. Fewer than $length bytes may be returned if underlying stream -
call returns fewer bytes. - @return string|false Returns the data read from the stream, false if
-
unable to read or if an error occurs.
*/
public function read($length)
{
return $this->output();
}/**
-
@return string
*/
public function getContents()
{
return $this->output();
}
/**
- @link http://php.net/manual/en/function.stream-get-meta-data.php
- @param string $key Specific metadata to retrieve.
- @return array|mixed|null Returns an associative array if no key is
-
provided. Returns a specific key value if a key is provided and the -
value is found, or null if the key is not found.
*/
public function getMetadata($key = null)
{
if ($key === null) {
return array();
}
return null;
}
}
[/code] -
@var callable
1 Like