The document discusses approaches to software development, highlighting key characteristics and functionalities of software systems, such as malleability and maintainability. It outlines software engineering principles, development activities including analysis, design, and testing, as well as modeling techniques using UML for object-oriented systems. Essential topics covered include legacy systems, divide and rule strategies, and different views and models used in software analysis.

1. Arab Open University
2nd
Semester, 2006-2007
M301
Unit 4.1
Approaches to Software
Development
rattas@arabou.org.sa

2. Reem AlAttas © 2
Topic Road Map
 Software and software engineering
An introduction to software development
Modeling
Analyzing simple requirements
Introduction to the CASE tool

3. Reem AlAttas © 3
System
An assembly of components that are
connected together in an organized way.
Examples:
 Telephone.
 Human body.
 Super market software system.

4. Reem AlAttas © 4
Software Characteristics
Malleability: easy to change.
Complexity.
Size.
 The number of errors in a system increases
with complexity and size.

5. Reem AlAttas © 5
Software System Characteristics
Useful: meets user’s requirements.
Usable: easy to use.
Reliable: does not contain errors.
Flexible: easy to change.
Available: in its target environment.
Affordable: on time and within budget.

6. Reem AlAttas © 6
Maintainability
Software system must be maintainable 
written and documented in such a way
that changes can readily be made.
 Important to minimize changing costs.

7. Reem AlAttas © 7
Legacy systems
 Particular software system continues to meet its users’
needs.
 There may be little or no motivation to change or replace
it.
 Characteristics:
 Large.
 Critical to the system.
 Have probably been changed a number of times since their
inception.
 Difficult to understand.
 difficult to maintain.

8. Reem AlAttas © 8
Divide and rule
Decompose a problem into smaller and
smaller parts or chunks until each one can
be comprehended or dealt with by an
individual.
Example:
 Hospital system = patient system + physician
system + pharmacy system.

9. Reem AlAttas © 9
Divide and rule
 Partition  Projection

10. Reem AlAttas © 10
Divide and rule
Coupling: the degree of interdependence
among the different components of a
system.
Low coupling is better because:
 Changes to one component are less likely to
propagate through the rest of the system.
 Components are easy to replace and reuse.

11. Reem AlAttas © 11
Architecture
Describes the overall shape of the actual
or proposed software system.

12. Reem AlAttas © 12
Topic Road Map
Software and software engineering
 An introduction to software
development
Modeling
Analyzing simple requirements
Introduction to the CASE tool

13. Reem AlAttas © 13
Software Engineering
The establishment and use of sound
engineering principles in order to obtain
economically software that is reliable and
works efficiently on real machines.

14. Reem AlAttas © 14
Software Development Activities
1. Analysis: includes requirements elicitation
where you identify the problem and
requirements specification where you decide
what needs to be done to solve the problem.
2. Design: how you will solve the problem.
3. Implementation.
4. Testing.

15. Reem AlAttas © 15
Software Development Activities
5. Integration.
6. Maintenance.
7. Quality Management.
8. Project Management.

16. Reem AlAttas © 16
Waterfall Model

17. Reem AlAttas © 17
Iterative (Spiral) Development

18. Reem AlAttas © 18
Incremental Development

19. Reem AlAttas © 19
Topic Road Map
Software and software engineering
An introduction to software development
 Modeling
Analyzing simple requirements
Introduction to the CASE tool

20. Reem AlAttas © 20
Modeling
A way of thinking about things and ideas
in the ‘real world’.
Example:
 Map.

21. Reem AlAttas © 21
Modeling Language Rules
Syntax: determines what diagrams and
symbols exist.
Semantics: determines what the diagrams
and symbols mean.

22. Reem AlAttas © 22
UML
Unified Modeling Language used to
develop object-oriented software systems.

23. Reem AlAttas © 23
Types of Models
Static Models: describe the objects in a
software system and their relationships to
other objects.
Dynamic Models: describe the behavior of
a software system over time.

24. Reem AlAttas © 24
Views in the UML

25. Reem AlAttas © 25
Topic Road Map
Software and software engineering
An introduction to software development
Modeling
 Analyzing simple requirements
Introduction to the CASE tool

26. Reem AlAttas © 26
Problem

27. Reem AlAttas © 27
Tasks
1. Make reservation.
2. Check in.
3. Check out.

28. Reem AlAttas © 28
Use Case View  who does what

29. Reem AlAttas © 29
Main Elements
Actors.
Use Cases.
Relationships.

30. Reem AlAttas © 30
Static View  noun identification

31. Reem AlAttas © 31
Main Elements
Classes.
Associations.

32. Reem AlAttas © 32
Dynamic View
 Activity view: shows both sequential and
concurrent groups of activities of a specific task.
 Interaction view: concerned with the exchange of
messages between the objects in a software
system.
 State machine view: record the different
possibilities that might arise for all instances of a
particular class.

33. Reem AlAttas © 33
Activity View  Check in

34. Reem AlAttas © 34
Main Elements
Activities.
Transitions.
Decision points.
Start and end points.

35. Reem AlAttas © 35
Interaction View  Checking Jill into
the Ritz Hotel

36. Reem AlAttas © 36
Main Elements
Objects.
Messages.
Object’s life line.
Object is active.

37. Reem AlAttas © 37
State Machine View  Room Object

38. Reem AlAttas © 38
Main Elements
State.
Transition.

39. Reem AlAttas © 39
Topic Road Map
Software and software engineering
An introduction to software development
Modeling
Analyzing simple requirements
 Introduction to the CASE tool

40. Demo

41. TMA4 – Q1

42. Thank You!