1. Review for Exam #1 Chapters 1 - 8
Exam #1 – Thursday, Oct. 2
Review slides will be posted on the course web site:
Office hours
Dr. Skubic: Tues., 2-3:30 p.m.
Jason Goffeney: Tues., 12:30-1:50 p.m.
Wed., 1-3 p.m.

2. Chapter 1 – Overview and Intro to Software Engineering
Frequently Asked Questions from Fig. 1.1
What is the discipline of software engineering?
Why is it important? (development cost issues)
What is a software product? (programs, documentation, & configuration data)
What is the software process?
What are CASE tools?
Responsibilities and ethics

3. Chapter 2 – System Engineering
Relationship between the software and the system
System modeling – describing the architecture using a block diagram
The system engineering process and its challenges are similar to the software engineering process and its challenges
Emergent properties of reliability, usability, safety, security, and even performance

4. Chapter 3 – The Software Process
Generic development phases:
specification, design, implementation, testing/validation, maintenance/evolution
Software process models:
Waterfall
Evolutionary (revisit in Ch. 8) – exploratory vs. throw-away
Formal systems development
Re-use development
Iterative models – Incremental and Spiral
Under what conditions would you use each model?

5. Homework #1 Solutions
1. Pick the most appropriate generic software process model for a system to control anti-lock braking in a car
ANSWER: Formal systems development because of the safety-critical system
[from Chapter 3]

6. Homework #1 Solutions
1. Pick the most appropriate generic software process model for a virtual reality system to support software maintenance
ANSWER: Exploratory development because the requirements would be hard to determine in advance.
[from Chapter 3]

7. Homework #1 Solutions
1. Pick the most appropriate generic software process model for a university accounting system that replaces an existing system
ANSWER: The waterfall model would work here. The requirements should be stable because it is replacing an existing system. If there are existing components that are usable, then re-use development would also be appropriate.
[from Chapter 3]

8. Homework #1 Solutions
1. Pick the most appropriate generic software process model for an interactive system for railway passengers that finds train times from terminals installed in stations
ANSWER: The system will have a complex user interface but it must be stable and reliable. Use throw-away prototyping to find the requirements and then the incremental or waterfall model.
[from Chapter 3]

9. Homework #1 Solutions
2. Explain how both the waterfall model and the prototyping model can be accomplished in the spiral process model.
ANSWER: The spiral model will look different depending on the nature of the project and the associated risks. With low risk specification and no need for prototyping, the spiral model looks like the waterfall model. With high risk specification that calls for prototyping to discover the requirements, the spiral model looks like the prototyping model.
[from Chapter 3]

10. Chapter 4 – Project Management
Why is software project management so difficult?
Distinctive challenges, e.g., an intangible product
Management techniques
Milestones, reviews, deliverables
Bar charts and activity networks
Risk Management
Identifying risks
Different types of risks
Managing risks

11. Homework #1 Solutions
4. Explain why the intangibility of software systems poses special problems for software project management.
ANSWER: Software cannot be inspected like a concrete item such as a house. It is hard to tell exactly what the status of the development is.
[from Chapter 4]

12. Chapter 5 – Software Requirements
Types of requirements
User requirements vs. system requirements
Functional requirements vs. non-functional requirements
Domain requirements
How to represent requirements
structured language vs. PDL (program description language)
The software requirements document
What is included?
Potential problems
Listing requirements in measurable terms
Finding ambiguities and omissions

13. Homework #1 Solutions
3. Give an example to distinguish between user requirements and system requirements.
EXAMPLE:
User requirements: (in natural language) The hospital PDA must interface to a database which stores the patient information
System requirements: (with diagrams) Specify the type of database system and an entity-relationship diagram to show what patient information will be stored and with what relationships.
[from Chapter 5]

14. Homework #2 Solutions
1. Write user requirements for an unattended gas pump system using natural language in a standard way (like Fig and 5.11)
ANSWER:
1. Fuel delivery system
1.1 The system should provide an unattended fuel delivery service where a specified amount of fuel is delivered to customers. The cost is deducted from the customer’s credit card.
1.2 The sequence of actions to dispense fuel should be:
1. The customer selects the type of fuel to be delivered.
2. The customer inputs either a cash limit or the maximum amount of fuel to be delivered.
3. The customer validates the transaction by providing credit card details.
Rationale: The amount of fuel allowed depends on the credit limit but customers may wish to fill up rather than specify a certain amount of fuel. By specifying the maximum, the system can check if credit is available.
4. The pump is activated. Fuel is delivered.

15. HW #2, question 1, continued
5. The transaction is terminated either when the pump nozzle is returned to its holster for 15 seconds or when the customer’s fuel or cash limit has been reached.
Rationale: Termination should not be immediate when the nozzle is returned as the customer may wish to restart the transaction, e.g., to fill the fuel can as well as the car
6. A receipt is printed.
7. The fuel stock is updated.
Specification: PUMP_SYS/FS. Section 1.
[from Chapter 5]

16. Homework #2 Solutions
2. Describe any 2 types of non-functional requirements. Give an example for the gas pump system.
ANSWER:
examples: performance, efficiency, space, portability, safety, ethical, standards (See Fig. 5.3)
For gas pump system:
Must follow the standard interface look established by the client (e.g., layout and color)
Must be implemented on the client’s existing hardware platform
[from Chapter 5]

17. Chapter 6 – Requirements Engineering Processes
Phases (what artifact is produced after each phase?)
feasibility study
requirements elicitation and analysis
requirements specification
requirements validation (review slides)
Potential problems
e.g., stakeholders don’t know what they want; conflicts, etc.
VORD – viewpoint-oriented requirements def.
Use cases (review extra slides posted)
Associations – includes, extends, generalization

18. The requirements engineering process

19. Problems of requirements analysis
Stakeholders don’t know what they really want
Stakeholders express requirements in their own terms
Different stakeholders may have conflicting requirements
Organisational and political factors may influence the system requirements
The requirements change during the analysis process. New stakeholders may emerge and the business environment change

20. Home Automation example –
factor out common functionality with <include>

21. Home Automation example using <extend>

22. Simplified with an abstract use case - generalization

23. Homework #2 Solutions
3. Draw a Use Case diagram for the gas pump system
read & validate credit card
select fuel options
customer
dispense fuel
debit credit card
credit
card
company
<include>
[from Chapter 6]
print receipt

24. Chapter 7 – System Models
Context model
The context diagram
Behavioral model
Data flow diagram (also called process model)
State diagram
Data model
Entity-relationship diagram
Data dictionary
Object models
Hierarchy showing inheritance
Aggregation

25. Context Diagram The context of an ATM system

26. Homework #2 Solutions
4. Draw a context diagram for a patient information system in a hospital. Include image storage for x-rays and a patient admissions system.
image database
medical
records
system
hospital
admissions
system
patient information
system
drug dispensing
system
[from Chapter 7]

27. Data Flow Diagram: Equipment procurement process
Process Models show the overall process and the processes that are supported by the system

28. State Diagram Microwave oven model

29. Entity-Relationship Diagram Semantic Data model of a Software design
Lack details and need to be supplemented by DD

30. Class Diagram: Part of a Library class hierarchy
Name of object class
Class Diagram: Part of a Library class hierarchy
Class attributes
Object’s operations

31. Class Diagram: Object aggregation

32. Chapter 8 – Software Prototyping
Evolutionary prototyping
Start with requirements you understand the best
Deliver the prototype
Throw-away prototyping
Start with requirements you least understand
Throw away the prototype and start over
Advantages & Disadvantages
Rapid prototyping techniques
HL language, DB programs, component assembly with re-usable components
User interface prototyping