This PHP example program demonstrates four ways to send and receive JSON data.

PostJsonRequests.php

<?php

echo "Relevant variables:<hr />";
echo '$_SERVER["HTTPS"] = '.$_SERVER['HTTPS']."<br />";
echo '$_SERVER["HTTP_HOST"] = '.$_SERVER['HTTP_HOST']."<br />";

echo '$_SERVER["SERVER_NAME"] = '.$_SERVER['SERVER_NAME']."<br />";
echo '$_SERVER["SERVER_PORT"] = '.$_SERVER['SERVER_PORT']."<br />";

echo 'dirname($_SERVER["PHP_SELF"]) = '.dirname($_SERVER["PHP_SELF"])."<br />";

/*
// To see all of the server values, use this loop or call phpinfo();
foreach ($_SERVER as $sIndex => $sValue)  {
	echo '$_SERVER["'.$sIndex.'"] = '.$sValue."<br />";
}
*/

$qsData = array(
  'user'	=> 'XoaX',
  'id'		=> 1,
);

$qPostOptions = array(
  'http' => array(
    'method'  => 'POST',
    'content' => json_encode( $qsData ),
    'header'=>  "Content-Type: application/json\r\n" .
                "Accept: application/json\r\n"
    )
);

// Set the protocol
if (!empty($_SERVER['HTTPS']) && (strtolower($_SERVER['HTTPS']) == 'on' || $_SERVER['HTTPS'] == '1')) {
	$sProtocol = 'https';
} else {
	$sProtocol = 'http';
}
$sUrlBase = $sProtocol."://".$_SERVER['SERVER_NAME'].":".$_SERVER['SERVER_PORT'].dirname($_SERVER["PHP_SELF"]);


// ************** FIRST REQUEST **************
echo "<br /><br /><br />First request (using file_get_contents('php://input')):<hr />";
// Create the URL for this directory and the file that we are contacting 
$sUrl1 = $sUrlBase."/PostJsonResponse1.php";
echo "First URL = ".$sUrl1."<br />";

// Make the post request
$qContext  = stream_context_create( $qPostOptions );
//Note that this won't work if the allow_url_fopen setting is set to Off in the php.ini file.
$sResult = file_get_contents( $sUrl1, false, $qContext );

// Display the result string
echo "The response result #1 was ".$sResult."<br />";
$qResponse = json_decode( $sResult );
// Display the decoded object
echo "<pre>".json_encode($qResponse, JSON_PRETTY_PRINT)."</pre>";




// ************** SECOND REQUEST **************
echo "<br /><br /><br />Second request (using \$_POST):<hr />";
// Create the URL for this directory and the file that we are contacting 
$sUrl2 = $sUrlBase."/PostJsonResponse2.php";
echo "Second URL = ".$sUrl2."<br />";

$qPostOptions['http']['content'] = "json=".json_encode( $qsData );
// NOTE: The type must application/x-www-form-urlencoded for the $_POST variable to be filled
$qPostOptions['http']['header'] = "Content-Type: application/x-www-form-urlencoded\r\n"."Accept: application/json\r\n";
// Make the post request
$qContext  = stream_context_create( $qPostOptions );
$sResult = file_get_contents( $sUrl2, false, $qContext );

// Display the result string
echo "The response result #2 was ".$sResult."<br />";
$qResponse = json_decode( $sResult );
// Display the decoded object
echo "<pre>".json_encode($qResponse, JSON_PRETTY_PRINT)."</pre>";




// ************** THIRD REQUEST **************
echo "<br /><br /><br />Third request (using Curl):<hr />";
// Reuse the first URL for the third call
echo "Third URL = ".$sUrl1."<br />";
$qCurl = curl_init($sUrl1);
curl_setopt($qCurl, CURLOPT_RETURNTRANSFER, true);
curl_setopt($qCurl, CURLOPT_CUSTOMREQUEST, "POST");
curl_setopt($qCurl, CURLOPT_HTTPHEADER, array('Content-Type:application/json'));
curl_setopt($qCurl, CURLOPT_POST, true);
curl_setopt($qCurl, CURLOPT_POSTFIELDS, json_encode($qsData));
$sResult = curl_exec($qCurl);
curl_close($qCurl);

// Display the result string
echo "The response result #3 was ".$sResult."<br />";
$qResponse = json_decode( $sResult );
// Display the decoded object
echo "<pre>".json_encode($qResponse, JSON_PRETTY_PRINT)."</pre>";





// ************** FOURTH REQUEST **************
echo "<br /><br /><br />Fourth request (using http_build_query() and \$_POST):<hr />";
// Reuse the second URL for the third call
echo "Fourth URL = ".$sUrl2."<br />";
$aPairs = ['json' => json_encode( $qsData )];
$qPostOptions['http']['content'] = http_build_query($aPairs);

// Make the post request
$qContext  = stream_context_create( $qPostOptions );
$sResult = file_get_contents( $sUrl2, false, $qContext );

// Display the result string
echo "The response result #4 was ".$sResult."<br />";
$qResponse = json_decode( $sResult );
// Display the decoded object
echo "<pre>".json_encode($qResponse, JSON_PRETTY_PRINT)."</pre>";

?>

PostJsonResponse1.php

<?php

// Retrieve the raw POST data
$sJsonData = file_get_contents('php://input');
// Decode the JSON data into a PHP associative array
$qJsonObject = json_decode($sJsonData, true);
// Check if decoding was successful
if ($qJsonObject !== null) {
	// Access the data and perform operations
	$sName = $qJsonObject['user'];
	$iId = $qJsonObject['id'];

	$qReturnedObject = new stdClass();
	// Change the values before we return it.
	$qReturnedObject->name = $sName.".net";
	$qReturnedObject->value = $iId + 1;

	// Encode and return the Json string of the object
	$sReturnedJSON = json_encode($qReturnedObject);
	echo $sReturnedJSON;

} else {
   // The JSON decoding failed, return a 400 bad request
   http_response_code(400);
   echo "Invalid JSON data";
}


?>

PostJsonResponse2.php

<?php

// This takes the request as urlencoded data. This is required for the $_POST to be filled.
// Retrieve the raw POST data
$sJsonData = $_POST;

// Make sure that the data is available
if (!empty($sJsonData)) {
	$Json = $_POST['json'];
	$qObject = json_decode($Json, true);

	// Access the data and perform operations
	$sName = $qObject['user'];
	$iId = $qObject['id'];

	$qReturnedObject = new stdClass();
	// Change the values before we return it.
	$qReturnedObject->name = $sName.".net 2";
	$qReturnedObject->value = $iId + 2;

	// Encode and return the Json string of the object
	$sReturnedJSON = json_encode($qReturnedObject);
	echo $sReturnedJSON;

} else {
   // The JSON decoding failed, return a 400 bad request
   http_response_code(400);
   echo "Error: The data must be urlencoded data for $_POST to be fillled.";
}


?>

Output