software Engineering lecture notes, Lecture notes of Software Engineering

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Software Engineering

Lectures

Lecture Objectives

 Introduce software engineering and to explain its importance  Develop a broad understanding of the software engineering domain

Software Engineering

Definition

 Software engineering is the application of engineering to the design, development, implementation, testing and maintenance of software in a systematic method.

What is software?

 Software refers to a program or a set of instructions and applications used to manage and control various functions of a device such as a computer. Unlike hardware, which represents a physical part of a device, software is virtual.  Software products may be developed for a particular customer or may be developed for a general market

Software’s Dual Role

 Software is a product  (^) Delivers computing potential  (^) Produces, manages, acquires, modifies, displays, or transmits information  Software is a vehicle for delivering a product  (^) Supports or directly provides system functionality  (^) Controls other programs (e.g. operating systems)  (^) Effects communications (e.g. networking software)  (^) Helps build other software (e.g. software tools)

Software Applications

 No clear breakdown of application types, following are some generally accepted overlapping categories  System software  Real-time software  Business information software  Engineering & scientific software  Embedded software  Personal application software  Communication software

Attributes of a Good Software

Cost Performance

Attributes of a Good Software

 Maintainability  Software must evolve to meet changing needs;  Dependability  Software must be trustworthy; e.g. reliability, security, safety.  Efficiency  Software should not make wasteful use of system resources;

Software Development

Process

 A set of activities whose goal is the development or evolution of software.  Generic activities in all software processes are  Specification - what the system should do and its development constraints  Development - production of the software system  Validation - checking that the software is what the customer wants  Evolution - changing the software in responses to changing demands

Software Process Model

 A simplified representation of a software process, presented from a specific perspective.  Examples of process perspectives are  Workflow - sequence of activities  Data-flow - information flow  Role/action - who does what

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What is a software process?

 A set of ordered tasks to produce indented output of some kind  Involving activates, constraints; and  Resources  The process of building a software product  Life cycle - describes the life of the software from conception through its implementation, delivery, use and maintenance.

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Why we need software process?

 Common understanding of the activities, resources and constraints involved in software development.  Creating processes helps  Find inconsistencies,  Redundancies; and  Omissions

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Waterfall Model

Requirements definition System and software design Implementation and unit testing Integration and system testing Operation and maintenance

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Waterfall Model

 Inflexible partitioning of the project into distinct stages  Makes it difficult to respond to changing customer requirements.  Model is only appropriate when the requirements are well-understood; and  changes will be fairly limited during the design process. Few business systems have stable requirements.