What are Pull-MVC and push-MVC based architecture ? Which architecture does Struts2 follow ?

Pull-MVC and Push-MVC are better understood with how the view layer is getting data i.e. Model to render. In case of Push-MVC the data( Model) is constructed and given to the view layer by the Controllers. Typical example is Spring MVC and Struts1. Pull-MVC on the other hand puts the model data typically constructed in Controllers are kept in a common place , which then gets rendered by view layer. Struts2 is a Pull-MVC based architecture, in which all data is stored in Value Stack and retrieved by view layer for rendering.