1. CS 281 Intro to Software Engineering Lecture 02 Software Engineering (1)

2. Chapter 2 Software Engineering These slides are designed to accompany Software Engineering: A Practitioner’s Approach, 8/e (McGraw-Hill 2014). Slides copyright 2014 by Roger Pressman.2 Slide Set to accompany Software Engineering: A Practitioner’s Approach, 8/e by Roger S. Pressman and Bruce R. Maxim Slides copyright © 1996, 2001, 2005, 2009, 2014 by Roger S. Pressman For non-profit educational use only May be reproduced ONLY for student use at the university level when used in conjunction with Software Engineering: A Practitioner's Approach, 8/e. Any other reproduction or use is prohibited without the express written permission of the author. All copyright information MUST appear if these slides are posted on a website for student use.

3. These slides are designed to accompany Software Engineering: A Practitioner’s Approach, 8/e (McGraw-Hill 2014). Slides copyright 2014 by Roger Pressman.3 Software Engineering Some realities: a concerted effort should be made to understand the problem before a software solution is developed design becomes a pivotal activity software should exhibit high quality software should be maintainable The seminal definition: [Software engineering is] the establishment and use of sound engineering principles in order to obtain economically software that is reliable and works efficiently on real machines.

4. These slides are designed to accompany Software Engineering: A Practitioner’s Approach, 8/e (McGraw-Hill 2014). Slides copyright 2014 by Roger Pressman.4 Software Engineering The IEEE definition: Software Engineering: 1)The application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software; that is, the application of engineering to software 2)The study of approaches as in (1)

5. These slides are designed to accompany Software Engineering: A Practitioner’s Approach, 8/e (McGraw-Hill 2014). Slides copyright 2014 by Roger Pressman.5 A Layered Technology Software Engineering Process defines a framework that must be established for effective delivery of software engineering technology Methods provide the technical how- to's for building software Tools provide automated or semi- automated support for the process and the methods An organization’s focus on quality fosters a continuous process improvement culture, and it is this culture that ultimately leads to the development of increasingly more effective approaches to software engineering

6. These slides are designed to accompany Software Engineering: A Practitioner’s Approach, 8/e (McGraw-Hill 2014). Slides copyright 2014 by Roger Pressman.6 A Process Framework Process framework Framework activities work tasks work products milestones/deliverables QA checkpoints Umbrella Activities Process frameworks establish the foundation for a complete software engineering process by identifying framework and umbrella activities Framework activities are applicable to all software projects, are applied (at times iteratively) one after the other Umbrella activities are applicable across the entire software process

7. These slides are designed to accompany Software Engineering: A Practitioner’s Approach, 8/e (McGraw-Hill 2014). Slides copyright 2014 by Roger Pressman.7 Framework Activities 1.Communication 2.Planning 3.Modeling a.Analysis of requirements b.Design 4.Construction a.Code generation b.Testing 5.Deployment

8. Communication is done to understand stakeholders' objectives for the project and to gather requirements that help define software features and functions Planning defines the work by describing the technical tasks to be conducted, the risks that are likely, the resources that will be required, the work products to be produced, and a work schedule Modeling is done to better understand requirements and the design that will achieve those requirements Construction activity combines code generation and testing that is required to uncover errors in the code Deployment is the delivery of the software to the customer who evaluates it and provides feedback

9. These slides are designed to accompany Software Engineering: A Practitioner’s Approach, 8/e (McGraw-Hill 2014). Slides copyright 2014 by Roger Pressman.9 Umbrella Activities Project tracking and control Risk management Quality assurance Technical reviews Measurement Configuration management Reusability management Work product preparation and production

10. Project tracking and control allows the software team to assess progress against the project plan and take any necessary action to maintain the schedule Risk management assesses and plans for tackling risks that may affect the outcome of the project or the quality of the product Quality assurance defines and conducts the activities required to ensure software quality Technical reviews assess software engineering work products in an effort to uncover and remove errors before they are propagated to the next activity

11. Measurement defines and collects process, project, and product measures that assist the team in delivering software that meets stakeholders' needs; can be used along with all other framework/umbrella activities Configuration management manages the effects of change throughout the software process Reusability management defines criteria for work product reuse (including software components) and establishes mechanisms to achieve reusable components Product preparation and production encompass the activities required to create work products such as models, documents, logs, forms, and lists

12. These slides are designed to accompany Software Engineering: A Practitioner’s Approach, 8/e (McGraw-Hill 2014). Slides copyright 2014 by Roger Pressman.12 Adapting a Process Model to Project’s and Team’s Needs the overall flow of activities, actions, and tasks and the interdependencies among them the degree to which actions and tasks are defined within each framework activity the degree to which work products are identified and required the manner which quality assurance activities are applied the manner in which project tracking and control activities are applied the overall degree of detail and rigor with which the process is described the degree to which the customer and other stakeholders are involved with the project the level of autonomy given to the software team the degree to which team organization and roles are prescribed

13. These slides are designed to accompany Software Engineering: A Practitioner’s Approach, 8/e (McGraw-Hill 2014). Slides copyright 2014 by Roger Pressman.13 The Essence of Practice George Polya suggested in “How to Solve It” (1957): 1.Understand the problem (communication and analysis) 2.Plan a solution (modeling and software design) 3.Carry out the plan (code generation) 4.Examine the result for accuracy (testing and quality assurance)

14. These slides are designed to accompany Software Engineering: A Practitioner’s Approach, 8/e (McGraw-Hill 2014). Slides copyright 2014 by Roger Pressman.14 Understand the Problem Who has a stake in the solution to the problem? That is, who are the stakeholders? What are the unknowns? What data, functions, and features are required to properly solve the problem? Can the problem be compartmentalized? Is it possible to represent smaller problems that may be easier to understand? Can the problem be represented graphically? Can an analysis model be created?

15. These slides are designed to accompany Software Engineering: A Practitioner’s Approach, 8/e (McGraw-Hill 2014). Slides copyright 2014 by Roger Pressman.15 Plan the Solution Have you seen similar problems before? Are there patterns that are recognizable in a potential solution? Is there existing software that implements the data, functions, and features that are required? Has a similar problem been solved? If so, are elements of the solution reusable? Can subproblems be defined? If so, are solutions readily apparent for the subproblems? Can you represent a solution in a manner that leads to effective implementation? Can a design model be created?

16. These slides are designed to accompany Software Engineering: A Practitioner’s Approach, 8/e (McGraw-Hill 2014). Slides copyright 2014 by Roger Pressman.16 Carry Out the Plan Does the solution conform to the plan? Is source code traceable to the design model? Is each component part of the solution provably correct? Has the design and code been reviewed, or better, have correctness proofs been applied to algorithm?

17. These slides are designed to accompany Software Engineering: A Practitioner’s Approach, 8/e (McGraw-Hill 2014). Slides copyright 2014 by Roger Pressman.17 Examine the Result Is it possible to test each component part of the solution? Has a reasonable testing strategy been implemented? Does the solution produce results that conform to the data, functions, and features that are required? Has the software been validated against all stakeholder requirements?

18. These slides are designed to accompany Software Engineering: A Practitioner’s Approach, 8/e (McGraw-Hill 2014). Slides copyright 2014 by Roger Pressman.18 Hooker’s General SE Principles 1: The Reason It All Exists 2: Keep It Simple, Stupid! 3: Maintain the Vision 4: What You Produce, Others Will Consume 5: Be Open to the Future 6: Plan Ahead for Reuse 7: Think!

19. The Reason It All Exists. A software system exists for one reason: to provide value to its users. All decisions should be made with this in mind Keep It Simple, Stupid! All design should be as simple as possible, but no simpler. This facilitates having a more easily understood, less error-prone and easily maintained system Maintain the Vision. A clear vision is essential to the success of a project. Without conceptual integrity, a system may become a patchwork of incompatible designs, held together by the wrong kind of screws What You Produce, Others Will Consume. Always specify, design, and implement knowing someone else will have to understand what you are doing.

20. Be Open to the Future. To ensure long term success, systems must be ready to adapt to future hardware/ software changes. To achieve that, design systems that solve the general problem, not just the specific one. Plan Ahead for Reuse. Planning ahead for reuse reduces the cost and increases the value of both the reusable components and the systems into which they are incorporated Think! Placing clear, complete thought before action almost always produces better results.. Applying the first six principles requires intense thought, for which the potential rewards are enormous.

21. SE382 Software Engineering Lecture 03a Software Engineering (2)

22. These slides are designed to accompany Software Engineering: A Practitioner’s Approach, 8/e (McGraw-Hill 2014). Slides copyright 2014 by Roger Pressman.22 Software Myths Affect managers, customers (and other non- technical stakeholders) and practitioners Are believable because they often have elements of truth, but … Invariably lead to bad decisions, therefore … Insist on reality as you navigate your way through software engineering

23. Software Myths: Example Management Myth If we get behind schedule, we can add more programmers and catch up (sometimes called the Mongolian horde concept)

24. Software Myths: Example Customer Myth A general statement of objectives is sufficient to begin writing programs – we can fill in details later

25. Software Myths: Example Practitioner’s Myth Software engineering will make us create voluminous and unnecessary documentation and will invariably slow us down

26. These slides are designed to accompany Software Engineering: A Practitioner’s Approach, 8/e (McGraw-Hill 2014). Slides copyright 2014 by Roger Pressman.26 How It all Starts SafeHome: Every software project is precipitated by some business need:  the need to correct a defect in an existing application  the need to the need to adapt a ‘legacy system’ to a changing business environment  the need to extend the functions and features of an existing application, or  the need to create a new product, service, or system

27. Project Example: SafeHome The SafeHome company has developed an innovative hardware box that implements wireless Internet connectivity in a very small form factor The idea is to use this technology to develop and market a comprehensive home automation product line. This would ultimately provide not only security functions, but also would enable control over telephone answering machines, lights, heating, air conditioning, and home entertainment devices The first generation of the system will only focus on home security since that is a market the public readily understands.