jnduli / ussdpages

Creating a finite-state automata for handling complex USSD logic

UssdPages

This is a demo app showing how the State design pattern can be used to create complex ussd menus.

Uses:

• Laravel 6
• Africa's Talking USSD Sandbox API

Notes

1. The classes in the Ussd folder represent the various states.
2. The input() method represents the transition between states.
   • Each state responds to input differently.
3. The Context classes manage what gets displayed to the user.
4. Some functionality had to be placed in the view methods of some states.

Advantages

1. Extensible - new states can be created easily by creating classes that implement the State interface.
2. Clean - each class has concise, understandable methods (hopefully).

Disadvantages

1. Complexity - the State pattern may be difficult to grasp without first understanding OOP and SOLID
2. Numerous files - if a lot of states are involved.
3. view() methods have side-effects.