1. Introduction to Software Engineering: Second Edition
Ronald J. Leach
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

2. Chapter 1: Introduction
Ronald J. Leach
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

3. Copyright Ronald J. Leach, 1997, 2009, 2014, 2015
Software Engineering
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

4. What is Software Engineering?
The application of engineering techniques to develop and maintain software that runs properly and is constructed in an efficient manner.
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

5. Copyright Ronald J. Leach, 1997, 2009, 2014, 2015
Software
Is changing rapidly
Rarely runs only on unconnected computers
Can run on smartphones (and others)
Is ubiquitous
Is often cloud-based
Often has security issues
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

6. Copyright Ronald J. Leach, 1997, 2009, 2014, 2015
Software Engineering
Is changing rapidly
Is rarely done by single individuals except for small projects
Uses existing software components and systems through APIs, IDEs, and more
Is rarely understood in detail by any one individual
Teams are almost always necessary
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

7. Goals of Software Engineering
Efficiency
Reliability
Usability
Modifiability
Portability
Testability
Reusability
Maintainability
Interoperability
Correctness
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

8. Typical Software Engineering Tasks
Analysis
Documentation
Requirements
Maintenance
Design
Quality Assurance
Coding
Training
Testing and Integration
Resource Estimation
Project Management
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

9. Copyright Ronald J. Leach, 1997, 2009, 2014, 2015
Software Life Cycle
Analysis
Requirements
Design
Coding
Testing and Integration
Delivery
Maintenance
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

10. Models of Software Development
The classical waterfall model
The rapid prototyping model
The spiral model
The market-driven model
An open source development model
The agile development model …
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

11. Models of software development can be:
Sequential
Iterative
Concurrent
Appropriate only for highly experienced software personnel
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

12. Software Engineering is Engineering!
Measurement is important
Time, effort, cost of development
Quality, usability of software
Acceptance by users: reasons why, why not
Use of measurements and assessments to improve processes, products
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

13. Copyright Ronald J. Leach, 1997, 2009, 2014, 2015
Which Metrics to Use?
The GQM paradigm of Basili and Rombach is useful.
Goals: What do we wish to achieve?
Questions: What questions must we answer to determine if goals are met?
Metrics: What metrics must be collected to answer the questions?
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

14. What do all models of software development have in common?
They use both current and older technologies as appropriate
They reuse the largest appropriate components that have as much of the necessary functionality as possible, to improve development efficiency
Evaluation of the process used
Deliverables !
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

15. Copyright Ronald J. Leach, 1997, 2009, 2014, 2015
Components and Reuse
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

16. Copyright Ronald J. Leach, 1997, 2009, 2014, 2015
What is a Component?
Components are the basic elements of reuse.
The terms component and module are often used interchangeably
A component may be source code, but often includes many other items.
A component is a software artifact that has distinct boundaries and that fits into a system.
But what is a “system”?
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

17. Copyright Ronald J. Leach, 1997, 2009, 2014, 2015
Systems
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

18. Copyright Ronald J. Leach, 1997, 2009, 2014, 2015
Systems
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

19. Copyright Ronald J. Leach, 1997, 2009, 2014, 2015
Huge Systems
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

20. Copyright Ronald J. Leach, 1997, 2009, 2014, 2015
Global Systems
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

21. Copyright Ronald J. Leach, 1997, 2009, 2014, 2015
The ultimate goal
Allow software engineers to treat software components as building blocks, the same way that mechanical and electrical engineers do.
MEs and EEs can specify what a component is supposed to do, then find one that meets the specifications.
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

22. Copyright Ronald J. Leach, 1997, 2009, 2014, 2015
The ultimate goal, cont.
Mechanical engineers can
determine the correct spring or fastener for an application by looking up the desired properties in a reference book or manual.
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

23. Copyright Ronald J. Leach, 1997, 2009, 2014, 2015
The ultimate goal, cont.
Electrical engineers can determine the correct resistor or capacitor for an application by looking up the desired properties in a reference book or manual.
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

24. Copyright Ronald J. Leach, 1997, 2009, 2014, 2015
The ultimate goal, cont.
In both engineering fields:
The cost of the desired object is easily obtained
There are no surprises as long as the component meets the manufacturer’s quality standards.
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

25. Copyright Ronald J. Leach, 1997, 2009, 2014, 2015
Software components
In software engineering, the situation is quite different.
The cost to purchase an existing, desired component may be easy to obtain.
However, the total cost of ownership is very difficult to determine.
There may be many surprises when trying to deploy the component as part of a software system.
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

26. Software components, cont.
Unlike the situation in electrical and mechanical engineering, it is difficult to tell if the software component meets the quality standards of the company or organization that intends to use the component.
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

27. Remember the ultimate goal
Allow software engineers to treat software components as building blocks, to do what a component is supposed to do to one that meets the specifications.
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

28. Copyright Ronald J. Leach, 1997, 2009, 2014, 2015
What is software reuse?
The process of developing software using software components that:
have well-defined standard interfaces
are carefully tested
have a well-defined functionality
have precisely defined performance.
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

29. Copyright Ronald J. Leach, 1997, 2009, 2014, 2015
What can be reused?
Algorithms
Architectures
Patterns
Complete applications
Data
Requirements
Designs
Source code
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

30. Copyright Ronald J. Leach, 1997, 2009, 2014, 2015
What can be reused?
Source code
Test plans and test cases
Documentation
Integration plans
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

31. Copyright Ronald J. Leach, 1997, 2009, 2014, 2015
What else can be reused?
The most extreme case is reusing entire systems. (This is common in web-based software.)
COTS (Commercial, Off-The-Shelf) software products are often considered to be components when they are used to help comprise a system.
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

32. Copyright Ronald J. Leach, 1997, 2009, 2014, 2015
Software Life Cycles
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

33. The classical waterfall model
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

34. The rapid prototyping model
Initial
specifications
Develop prototype
Create new
specifications
Test and
integrate
prototype
Evaluate
prototype
System
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

35. Copyright Ronald J. Leach, 1997, 2009, 2014, 2015
The spiral model
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

36. The spiral model, one quadrant
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

37. The spiral model, one quadrant
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

38. The spiral model, one quadrant
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

39. The spiral model, one quadrant
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

40. Open Source Development
Requires deep knowledge of what is available open source
Many software products in repositories are not in completely stable form
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

41. Market-driven development
Requires great imagination to determine worthwhile projects
Highly risky way to run a career, at least at the beginning
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

42. Agile Software Development Process
Completed versions, more sturdy that prototypes, are delivered as often as weekly
Fulfilling highest priority requirements is often done first
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

43. Copyright Ronald J. Leach, 1997, 2009, 2014, 2015
A CASE tool
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

44. Copyright Ronald J. Leach, 1997, 2009, 2014, 2015
Note the complexity
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

45. Copyright Ronald J. Leach, 1997, 2009, 2014, 2015
Software Evolution
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

46. Copyright Ronald J. Leach, 1997, 2009, 2014, 2015
Software Evolves
Applications software
Operating systems
Databases
APIs
IDEs
COTS products
Interacting software components
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

47. The software conundrum
Buy?
Build?
Reuse?
Reengineer?
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

48. Commonly Used Standards
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

49. Primarily U.S. Standards
The Capability Maturity Model (CMM) from the Software Engineering Institute (SEI)
The CMM model has been superseded by the Capability Maturity Model Integration CMMI.
The Process Improvement Paradigm (PIP)
NASA Goddard Space Flight Center.
Department of Defense standard MIL-STD 2167A.
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

50. Primarily U.S. Standards
Department of Defense standard MIL-STD 1574A.
Department of Defense standard MIL-STD 882C.
Electronic Industries Association (EIA) SEB-6-A.
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015

51. Primarily International Standards
The European ESPRIT project.
The International Standards Organization (ISO) standard ISO 9001.
United Kingdom MOD 0055.
Copyright Ronald J. Leach, 1997, 2009, 2014, 2015