<?php
$url = 'https://estandartest.papelcero.es/api/avanws.php';
$data = array (
    "grant_type" => "client_credentials",
    "client_secret" => "6J5gn47A-def1-4515-9a62-000fGbn1s76zx",
    "client_id" => "API-XONE_dev",
    "service" => "servToken",
    "code" => "8356e8922cdccb82gh538fu2"
);
$headers = [];
$result = curlPost($url,$data,$headers);
print_r($result);

$imagen_temporal  = "doc_api.pdf";
$fp     = fopen($imagen_temporal, 'r');
$file = fread($fp, filesize($imagen_temporal));
fclose($fp);
$file = base64_encode($file);
$size = 12345;//Tamaño del Documento a adjuntar
$headers = array(
    'authorization-token: Bearer ' . $result->servToken->client_token,
    'client-id: API-XONE_dev',
    'p0-api-key: yyg648hnsu6659jnny3247ab' 
);
$data = array(
    'service' => 'servUpdateDoc',
    'doc_name' => 'doc_prueba_api_3.pdf',
    'doc_size' => $size,
    'doc_fichero' => $file,
    'doc_file' => 'VN-11-VWG',
    'doc_car' => 5000002
);

$result = curlPost($url,$data,$headers);
print_r($result);
function curlPost($url,$data,$headers) {
    $ch = curl_init();
    $timeout = 30;
    curl_setopt($ch, CURLOPT_URL,$url);
    curl_setopt($ch, CURLOPT_POST, TRUE);
    curl_setopt($ch, CURLOPT_POSTFIELDS, $data);
    curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, $timeout);
    $response = curl_exec ($ch);
    if (curl_errno($ch)) {
        echo 'Error:' . curl_error($ch);
    }
    curl_close ($ch);
    return json_decode($response);
}
function curlGetData($url,$headers) {

    $ch = curl_init();
    $timeout = 30;
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_HTTPGET,true);
    curl_setopt($ch, CURLOPT_HTTPHEADER,$headers);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, $timeout);

    $result = curl_exec($ch);
    curl_close($ch);
    return $result;
}
?>