This file contains import design considerations for this assignment:

1. I have created simple Java based objects to implement the requirement to keep the solution simple,
   SalesMessageListener class provides the entry point for processing message, the solution can 
   be easily extended to REST or JMS to provide industry standard processing capabilities.

2. I have preferred template pattern to implement message processing logic as it can be easily extended,
    (as in AdjustmentProcessor which extends sale processing to add adjustment logic) and can also be used
    to model system wide requirements like creating a sales report after every 10 messages are processed.

3. I have preferred Junit and Mockito have been used for unit testing as I have good understanding of these libraries.

4. As there is a requirement to keep the number of third party jars to minimum, I have used a ObjectFactory class
   to create objects instead of a IOC framework like Spring.