Symfony2 + NodeJS + AngularJS?

First, I believe we need to clarify some misunderstandings regarding the real time and AngularJS. AngularJS $http and $resource use Ajax in the background.

To have real time communication where the server pushes information to the client (instead of responding to Ajax calls), you would have to use Websockets. There are several alternatives in this domain, for example, socket.io integrates very well with nodejs, Ratchet socketo.me is specific for PHP, or you can use a 3rd party like Pusher through github.com/pusher/pusher-angular.

Second, you can certainly invoke PHP scripts from nodejs, however, unless you have a very specific reason to do so, it seems to me that it defeats the purpose of using nodejs. If you do not have such a requirement on use nodejs.

Of course yes.You can have nodejs and symfony2 in your server.you can use nodejs inside Symfony2 using CLI method.in front-end you can use angular and nodejs (converted).There is nodejs package,which lets you to convert your nodejs code to browser(browserify) side code and you can use it with angularjs.NodeJs has a package called socket.io.You can use it to have biDirectinal connection between server and client.