使用Zend框架从PHP服务器收到HttpResponse 400

I am trying to send push notifications to my android application using PHP server with Zend framework, but i am getting the HttpResponse as : The request could not be parsed as JSON or contains invalid fields, with the error code 400. I have used the server code as given in the demo of Zend framework, which is as follows :I am trying to send push notifications to my an