public function generatePdf(Template $template)
 {
     $guzzleclient = new GuzzleClient();
     $res = $guzzleclient->post($this->url . '/api/v1', ['auth' => [$this->user, $this->password], 'headers' => ['content-type' => 'application/json'], 'body' => $template->serialize()]);
     if ($res->getStatusCode() == 201) {
         return json_decode($res->getBody(), true)['id'];
     }
 }
<?php

include_once __DIR__ . '/../vendor/autoload.php';
use PdfGenereationServer\ApiClient\Client;
use PdfGenereationServer\ApiClient\Model\Template;
$client = new Client("user", "user", "http://127.0.0.1:8080");
$data = [];
$data['things'] = [];
$data['things'][] = ['id' => 1, 'name' => 'Apple', 'description' => 'The round fruit of a tree of the rose family, which typically has thin green or red skin and crisp flesh.'];
$template = new Template();
$template->setName('things index part');
$template->setData($data);
$id = $client->generatePdf($template);
if ($id) {
    echo 'succes';
    // put to queue for example
} else {
    echo 'failure';
}