CakePHP integration with ExtJS 3

Hello, I am a PHP and ExtJS user. I am looking into developing an application using a good PHP framework (CakePHP; good as in "I consider this good for me") and ExtJS version 3. What I would like to achieve is a complete Ext viewport with many grids and functions that would call PHP urls for retrieving data, saving data, edit/remove data (not just for grids, also for treepanel and such). I would like to use CakePHP as backend with all its capabilities for executing these functions. My first goal is to integrate the obAuth component (or any other secure authentification plugin for CakePHP) with an ExtJS 3 login interface. I am searching for the best method of combining these too so that I can easily restrict functions based on the usergroup access. I am thinking of a setup where the logged in user makes one post from Ext regarding the execution of a function and the CakePHP response made present as errors or notifiers through Ext alert boxes.

Do you think this is possible ? Any thoughts of an ideal config for this ?

Thank you.