Sample code for handling a trigger callback from the Geotrigger API. See http://developers.arcgis.com/en/geotrigger-service/api-reference/trigger-create/

trigger-callback.php

<?php
$jsonInput = file_get_contents("php://input");
$input = json_decode($jsonInput);

#file_put_contents('./tmp/'.date('Ymd-His').'.json', $jsonInput);

$device_id = '';
$client_id = '';
$client_secret = '';

// First get an application access token 
$ch = curl_init('https://www.arcgis.com/sharing/oauth2/token');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query(array(
	'grant_type' => 'client_credentials',
	'client_id' => $client_id,
	'client_secret' => $client_secret
)));
$response = curl_exec($ch);
$token = json_decode($response);

if($token->access_token) {
	echo $token->access_token . "\n";
	
	if($input->trigger && $input->trigger->properties && $input->trigger->properties->title) {
		$text = 'Entered ' . $input->trigger->properties->title;
	} else {
		$text = 'Unknown trigger';
	}
	
	// Send a push notification to the device
	$ch = curl_init('https://geotrigger.arcgis.com/device/notify');
	curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
	curl_setopt($ch, CURLOPT_POST, true);
	curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query(array(
		'deviceIds' => $device_id,
		'text' => $text
	)));
	curl_setopt($ch, CURLOPT_HTTPHEADER, array(
		'Authorization: Bearer '.$token->access_token
	));
	$response = curl_exec($ch);
	echo $response;
}