SUMMARY

As you construct the Schocr system's architecture, you should be guided by two principal design criteria: information hiding and planning for a family of related applications (as described in the "Future Directions and Expected Changes" section of the Official Requirements). The architecture and class interface design should be clear, easy to understand, easy to implement, easy to change. A design that "just works" but is not consistent with the design principles presented in class will not get full credit. Apply the software engineering principles introduced in the lectures, particularly modularity based on information hiding.

Complete the assignment by yourself. Do not work in teams on this assignment.

ASSIGNMENT DETAILS

Part of the assignment is to turn in drafts of your class diagram and one class interface specification at the start of lecture on Friday, Nov. 9, 2007. The drafts should reflect serious thought, but they will not be graded and you can make any changes you see fit in your final version turned in on Friday, Nov. 16.

You will not turn in an electronic copy of this homework. Turn in the paper document promptly at 1:00 pm at the start of lecture on Friday, Nov. 16. Your document should be stapled or bound at the left margin. At the front of your homework put the attached cover sheet.

Your document for homework 2 should have the following sections:

1. Cover Sheet (attached).
2. Table of Contents with page numbers.
3. Introduction. Provide a brief overview of the system, from the point of view of the system architect. Discuss the architectural style of the system, using one or more of the styles discussed in lecture. The purpose of this section is to give the reader a clear sense of the overall design and architecture of the system, how the classes will fit together, and the fundamental choices you made.
4. Design Rationale. List between seven and twelve important design decisions or procedures that your design encapsulates or hides in classes. Describe why each "secret" is important, and name the class that encapsulates it.
5. Class Diagram. Follow the general style of Figures 12.3, 12.4, and 12.5 in the textbook. More detail and examples will be provided in discussion. To create the diagram you may use any software you are familiar with, or you are welcome to draw it neatly by hand.
6. Class Interface Specifications. For every class in your design, specify its interface. Each class specification describes:
   • The purpose of the class. What part of the Official Requirements does it address? Use the "A-1" type identifiers to reference the Official Requirements document. Describe the rationale for constructing this class, including any secrets it encapsulates.
   • The class's interface. What services does the class provide (export) to client classes? Describe the interface by listing public method prototypes with descriptive names. If the class's interface includes public variables, list them as well. Describe each interface element clearly, and list one or more clients which will use it. For instance,

     	public int compare(String s1, String s1);
     	  // Returns -1 if s1 is shorter (has fewer characters) than s2,
               // 0 if s1 and s2 are the same length, 1 otherwise.
     	  // Client: class Book's method alphabetize().
     	

   • Any other information that will aid in the understanding of the class, such as its parent in an inheritance hierarchy, or performance constraints on the class or one of its methods.
   Your interface specification should be precise enough that any correct implementation of the class will integrate with the rest of the system.
7. Integration Test Plan. Provide a plan to incrementally test classes and collections of classes, with a focus on ensuring compatible interfaces. Describe your general approach (e.g. top-down) and what additional code or programs will have to be written to support the testing. Even if your Integration Test Plan is not complete, make sure that it is specific regarding a subset of classes and test cases.

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