Node.js with traditional PHP framework: How to combine?

I am impressed of Node.js but have small problems trying to imagine how I could combine two different server-side apps.

Example:

Imagine you have some little Facebook clone. Now it would be a good idea to do let node.js (or express) handle chat function.

Should I know just use node.js for this single task and if I know want to access some chat messages in the main app by PHP than just fetch tha chat message with some orm or odm? So that only the database is a connector between JavaScript and PHP serverside?

Doesn't this two world development make things harder?

Regards.

As first approach you can do the following (we have this implemented and works ok):

  1. Php to nodejs comm: implement a 'handler' in nodejs to listen for curl petitions launched from php to it.

  2. nodejs to php: use http.get() method in nodejs to call some kind of api in your php application

Easy and robust :)