The 'Controller' module is "C" in the Model-View-Controller (MVC) architectural pattern.
It can be useful if you want to use MVC in Drupal like it can be done in MVC frameworks (like ZF, Yii and so on).
The 'controller' module allows to use a Page Controllers (Action Controllers) for your pages. The Controller is just class that has set of actions. Each action is a separate method that will be called for specified path (page).
For example if you have the 'foo/bar' path (URI), then you can create a new class called FooBarPageController and myAction method (you can use other names of course). This method will be called for the 'http://host/foo/bar' address.
Important note 1: it is utility module for programmers only.
Important note 2: the Controller object that acts as page handler is not the same as Controller that implements DrupalEntityControllerInterface - they are different things and used for different purposes.
Document prototyping is a methodology for rapidly creating documents with similar attributes. Documents which have a general template, like a contract or a RFQ, can be easily created using Document Prototyping. This methodology can save precious time which otherwise would have been used for "copy-pasting" names, prices and other details into documents using your favorite word-processor.
About This Module
This module enables you to easily create and manage documents, in a way that's modular and integrate-able . For instance, you can create a "Customer" content-type, and using a custom module of your own - automatically attach documents related to that customer. This enables you to better manage your drupal customer database.
This module enables the creation of document prototypes - a template which contains "placeholders"/"tokens" for replacement, thus enabling a user to create similar documents with minor changes quickly an efficiently. It can turn one of the most tedious tasks into something quick and easy. This module intends to make it easier for users to create documents such as standard contracts, simple RFQs etc.