How to post stream/moment on Google using PHP

Question

Just like Facebook and Twitter, I want to add a post on Google+ using PHP from my website, but it's not working.

I searched the Internet and it always says that it's not possible to add streams using APIs. Is that correct? If not, what's a better solution?

<?php
/*
 * Copyright 2011 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
include_once "templates/base.php";
session_start();

require_once realpath(dirname(__FILE__) . '/../src/Google/autoload.php');

/************************************************
  We'll setup an empty 20MB file to upload.
 ************************************************/
DEFINE("TESTFILE", 'testfile.txt');
if (!file_exists(TESTFILE)) {
  $fh = fopen(TESTFILE, 'w');
  fseek($fh, 1024*1024*20);
  fwrite($fh, "!", 1);
  fclose($fh);
}

/************************************************
  ATTENTION: Fill in these values! Make sure
  the redirect URI is to this page, e.g:
  http://localhost:8080/fileupload.php
 ************************************************/
$client_id = 'xxxxxxxxxx-zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz.apps.googleusercontent.com';
$client_secret = 'xxxxxxxxxxxxxxxxx';
$redirect_uri = 'http://www.objectinstance.com/share/google1/examples/fileupload.php';

$client = new Google_Client();
$client->setClientId($client_id);
$client->setClientSecret($client_secret);
$client->setRedirectUri($redirect_uri);
$client->addScope("https://www.googleapis.com/auth/plus.login");
$service = new Google_Moment($client);

if (isset($_REQUEST['logout'])) {
  unset($_SESSION['upload_token ']);
}

if (isset($_GET['code'])) {
  $client->authenticate($_GET['code']);
  $_SESSION['upload_token'] = $client->getAccessToken();
  $redirect = 'http://' . $_SERVER['HTTP_HOST'] . $_SERVER['PHP_SELF'];
  header('Location: ' . filter_var($redirect, FILTER_SANITIZE_URL));
}

if (isset($_SESSION['upload_token']) && $_SESSION['upload_token']) {
  $client->setAccessToken($_SESSION['upload_token']);
  if ($client->isAccessTokenExpired()) {
    unset($_SESSION['upload_token']);
  }
} else {
  $authUrl = $client->createAuthUrl();
}

/************************************************
  If we're signed in then lets try to upload our
  file.
 ************************************************/
if ($client->getAccessToken()) {
    $moment_body = new Google_Service_Plus();
    $moment_body->setType("http://schema.org/AddAction");
    $item_scope = new Google_ItemScope();
    $item_scope->setUrl("https://developers.google.com/+/plugins/snippet/examples/thing");
    $moment_body->setObject($item_scope);
    $momentResult = $plus->moments->insert('me', 'vault', $moment_body);

    # This example shows how to create moment that does not have a URL.
    $moment_body = new Google_Moment();
    $moment_body->setType("http://schema.org/AddAction");
    $item_scope = new Google_ItemScope();
    $item_scope->setId("target-id-1");
    $item_scope->setType("http://schema.org/AddAction");
    $item_scope->setName("The Google+ Platform");
    $item_scope->setDescription("A page that describes just how awesome Google+ is!");
    $item_scope->setImage("https://developers.google.com/+/plugins/snippet/examples/thing.png");
    $moment_body->setObject($item_scope);
    $momentResult = $plus->moments->insert('me', 'vault', $moment_body);
}
echo pageHeader("File Upload - Uploading a large file");
if (
    $client_id == '<YOUR_CLIENT_ID>'
    || $client_secret == '<YOUR_CLIENT_SECRET>'
    || $redirect_uri == '<YOUR_REDIRECT_URI>') {
  echo missingClientSecretsWarning();
}
?>
<div class="box">
  <div class="request">
<?php 
if (isset($authUrl)) {
  echo "<a class='login' href='" . $authUrl . "'>Connect Me!</a>";
}
?>
  </div>

    <div class="shortened">
<?php 
if (isset($result) && $result) {
  var_dump($result);
}
?>
    </div>
</div>
<?php
echo pageFooter(__FILE__);