A company sells toys by mail order. The company already has a product database, with a simple web interface, so that customers can get information about toys and prices. Currently, customers place orders by mail or by telephone.
The company decides to create a system for selling toys online. The system will have three components: a product database, a customer database, and an ordering system.
The plan is to develop the system in two phases:

Phase 1
• The product database will remain unchanged but the web interface will be replaced by the ordering system.
• A fully-featured version of the ordering system will be developed. Every effort will be made to create an ordering system that will need little or no modifications in Phase 2.
• A simple version of the customer database will be developed.

Phase 2
• A new product database will be created.
• Major enhancements will be made to the customer database.
• Minor changes may be made to the ordering system.

A: System Architecture 

a) For the system architecture of Phase 1, draw a UML interface diagram.

b) This part of the question applies to the customer database.
i. What architectural style would you use for the customer database?
ii. Why would you choose this style?
iii. Draw a UML diagram for this architectural style showing its use in this application.

B: Program Design
Careful design of the interface between the ordering system and the product database during Phase 1 will help the development of the new product database in

 Phase 2.
a) Create a UML class diagram for the system as follows.
i. ii. iii.
b) For i.
Use noun identification to list the candidate classes.
Select the classes. For each class, list at least one attribute and one operation. Draw a possible class diagram.
The interface between the ordering system and the product database:

Select a design pattern that will allow the product database to be replaced in Phase 2 without modifications to the ordering system. Why would you choose this design pattern?
ii.
c) Make a sequence diagram for ordering a toy.