title: AWS PHP SDK Promise doesnt work
body: <p>According to the <em><strong>promise</strong></em> feature:
  <a href="http://docs.aws.amazon.com/aws-sdk-php/v3/guide/guide/promises.html" rel="nofollow noreferrer">AWS PHP SDK V3</a>
  one should create a promise and the run the &quot;then&quot; function.</p>
  <p>My code:</p>
  <pre><code>$promise = $client-&gt;copyObjectAsync($params);
          $promise-&gt;then(function ($value) {
              echo &quot;The promise was fulfilled with {$value}&quot;;
          }, function ($reason) {
              echo &quot;The promise was rejected with {$reason}&quot;;
          });
  </code></pre>
  <p>but the promise doesnt run...(it stays in pending state)
  Only when i run the &quot;wait&quot; method (which is blocking) then the promise is executed.
  Do you have to use &quot;wait&quot; and if so why do i need async?</p>