Using grasp principle to do UML interaction class diagram-------POS machine instance

Several important grasp principles: 1. Controller mode 2. Creator mode (principle) 3. Information Expert mode (principle) 4. Cohesion Poly-low coupling The pattern described here is not a design pattern for specific events in Java

Several operations for the main success scenario: 1.makemewsale 2.enteritem 3.endsale 4.makepayments

1) Consider the interaction diagram: Refer to the contract of operation to

----Our first consideration is to select the controller for the system operation, according to the controller mode, so to send the message to register as the beginning of the system makenewsal.

-----Second, to create an instance of sale, according to the creator pattern, register is the candidate to create the sale, and there should be a collection in the register to hold the Saleslineitem,

　　　　　　　　

Using grasp principle to do UML interaction class diagram-------POS machine instance