(PECL yar >= 1.0.0)
Yar_Concurrent_Client::loop — Send all calls
$callback
   [, callable $error_callback
  ]] )Send all registed remote RPC calls.
callbackIf this callback is set, then Yar will call this callback after all calls are sent and before any response return, with a $callinfo NULL.
Then, if user didn't specify callback when registering concurrent call, this callback will be used to handle response, otherwise, the callback specified while registering will be used.
error_callbackIf this callback is set, then Yar will call this callback while error occurred.
Example #1 Yar_Concurrent_Client::loop() example
<?php
function callback($retval, $callinfo) {
     if ($callinfo == NULL) {
        echo "Now, all requests are sent, and no any response available\n";
     } else {
        echo "This is a remote call response, the method name is", $callinfo["method"], 
             ". calling sequence is " , $callinfo["sequence"] , "\n";
        var_dump($retval);
     }
} 
function error_callback($type, $error, $callinfo) {
    error_log($error);
}
Yar_Concurrent_Client::call("http://host/api/", "some_method", array("parameters"), "callback");
Yar_Concurrent_Client::call("http://host/api/", "some_method", array("parameters"));   // if the callback is not specificed, 
                                                                               // callback in loop will be used
Yar_Concurrent_Client::call("http://host/api/", "some_method", array("parameters"), "callback", NULL, array(YAR_OPT_PACKAGER => "json"));
                                                                               //this server accept json packager
Yar_Concurrent_Client::call("http://host/api/", "some_method", array("parameters"), "callback", NULL, array(YAR_OPT_TIMEOUT=>1));
                                                                               //custom timeout 
Yar_Concurrent_Client::loop("callback", "error_callback"); //send the requests, 
                                                           //the error_callback is optional
?>
The above example will output something similar to:
Now, all requests are sent, and no any response available This is a remote call response, the method name issome_method. calling sequence is 4 string(11) "some_method" This is a remote call response, the method name issome_method. calling sequence is 1 string(11) "some_method" This is a remote call response, the method name issome_method. calling sequence is 2 string(11) "some_method" This is a remote call response, the method name issome_method. calling sequence is 3 string(11) "some_method"