Introduction to Software Engineering: Fundamentals, Processes, and Ethics, Lecture notes of Software Engineering

Download Introduction to Software Engineering: Fundamentals, Processes, and Ethics and more Lecture notes Software Engineering in PDF only on Docsity!

Chapter 1- Introduction to Software EngineeringChapter 1- Introduction to Software Engineering

Introduction

Read chapter thoroughly

Key points

Exercises...

We will

Read project Deliverables and tentative lecture schedule

Read syllabus..

Form teams

Importance of class attendance; team participation; short quizzes.

Key: don't get behind...

History of Software Engineering p

Software crisis

Large complex systems - no scaling

Cost overruns, requirements not met, over budget, late

Let's start off with the basics:

Chapter 1 Introduction Frequently Asked Questions about Software Engineering Question Answer What are the key challenges facing software engineering? Coping with increasing diversity, demands for reduced delivery times and developing trustworthy software. What are the costs of software engineering? Roughly 60% of software costs are development costs, 40% are testing costs. For custom software, evolution costs often exceed development costs. What are the best software engineering techniques and methods? While all software projects have to be professionally managed and developed, different techniques are appropriate for different types of system. For example, games should always be developed using a series of prototypes whereas safety critical control systems require a complete and analyzable specification to be developed. You can’t, therefore, say that one method is better than another. What differences has the web made to software engineering? The web has led to the availability of software services and the possibility of developing highly distributed service-based systems. Web-based systems development has led to important advances in programming languages and software reuse.^3

Chapter 1 Introduction Essential Attributes of Good Software Often referred to as "Quality Metrics" Sometimes called "Non-Functional Requirements" 4 Product characteristic Description Maintainability Software should be written in such a way so that it can evolve to meet the changing needs of customers. This is a critical attribute because software change is an inevitable requirement of a changing business environment. Dependability and security Software dependability includes a range of characteristics including reliability, security and safety. Dependable software should not cause physical or economic damage in the event of system failure. Malicious users should not be able to access or damage the system. Efficiency Software should not make wasteful use of system resources such as memory and processor cycles. Efficiency therefore includes responsiveness, processing time, memory utilisation, etc. Acceptability Software must be acceptable to the type of users for which it is designed. This means that it must be understandable, usable and compatible with other systems that they use. 5

Chapter 1 Introduction

Software Engineering

 (^) Software engineering is an engineering discipline that is concerned with all aspects of software production from the early stages of system specification through to maintaining the system after it has gone into use.  (^) Engineering discipline  (^) Using appropriate theories and methods to solve problems bearing in mind organizational and financial constraints.  (^) All aspects of software production  (^) Not just technical process of development. Also project management and the development of tools, methods etc. to support software production. 7

Chapter 1 Introduction Software Process Activities (High level view)  (^) Software specifications , where customers and engineers define the software that is to be produced and the constraints on its operation.  (^) Software development , where the software is designed and programmed.  (^) Software validation , where the software is checked to ensure that it is what the customer requires.  (^) Software evolution , where the software is modified to reflect changing customer and market requirements. 6

Key examples of diverse systems Stand alone apps Interactive transaction-based apps Embedded real time systems Process control systems Batch systems Data collection systems. And more... 10

Chapter 1 Introduction Software Engineering Fundamentals  (^) Some fundamental principles apply to all types of software system Systems should be developed using a managed and understood development process. Dependability and performance are important for all systems. But there are many other quality metrics needed!! Understanding and managing the software specification and requirements (what the software should do) are vitally important. Where appropriate, you should reuse software that has already been developed rather than write new software. 8

Chapter 1 Introduction Web Software Engineering  (^) Software reuse is the dominant approach for constructing web-based systems. When building these systems, you think about how you can assemble them from pre-existing software components and systems.  (^) Web-based systems should be developed and delivered iteratively and incrementally. It is now generally recognized that it is impractical to specify all the requirements for such systems in advance.  (^) User interfaces are constrained by the capabilities of web browsers. Technologies such as AJAX allow rich interfaces to be created within a web browser but are still difficult to use. Web forms with local scripting are more commonly used. 10

Software Engineering Ethics  (^) Software engineering involves wider responsibilities than simply the application of technical skills.  (^) This is dramatically different than software development. years ago.  (^) Software engineers must behave in an honest and ethically responsible way if they are to be respected as professionals.  (^) Ethical behavior is more than simply upholding the law but involves following a set of principles that are morally correct. 14

ACM/IEEE Code of Ethics  (^) The professional societies in the US have cooperated to produce a code of ethical practice.  (^) We have these posted along our inner hallways.  (^) Members of these organizations sign up to the code of practice when they join.  (^) Absolutely you need to belong to the ACM, IEEE CS and perhaps a couple of others in your area of specialization.  (^) The Code contains eight Principles related to the behavior of and decisions made by professional software engineers, including practitioners, educators, managers, supervisors and policy makers, as well as trainees and students of the profession. 16

Chapter 1 Introduction The ACM/IEEE Code of Ethics 14

Software Engineering Code of Ethics and Professional Practice

ACM/IEEE-CS Joint Task Force on Software Engineering Ethics and Professional Practices

PREAMBLE

The short version of the code summarizes aspirations at a high level of the abstraction; the

clauses that are included in the full version give examples and details of how these aspirations

change the way we act as software engineering professionals. Without the aspirations, the

details can become legalistic and tedious; without the details, the aspirations can become high

sounding but empty; together, the aspirations and the details form a cohesive code.

Software engineers shall commit themselves to making the analysis, specification, design,

development, testing and maintenance of software a beneficial and respected profession. In

accordance with their commitment to the health, safety and welfare of the public, software

engineers shall adhere to the following Eight Principles:

Ethical Dilemmas  (^) Disagreement in principle with the policies of senior management. Discuss  (^) Your employer acts in an unethical way and releases a safety-critical system without finishing the testing of the system. Discuss  (^) Participation in the development of military weapons systems or nuclear systems. Discuss 19

Here in the following slides are some introductory thoughts regarding architecture. We will be taking through many of these in future lectures. But for now... 20