Chapter 1 - Introduction to Software Engineering

What is software?

Computer programs and associated documentation. Software products may be developed for a particular customer or may be developed for a general market.

What are the attributes of good software?

Good software should deliver the required functionality and performance to the user and should be maintainable, dependable and usable

What is 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.

What are the fundamental software engineering activities?

Software specification, software development, software validation and software evolution

What is the difference between software engineering and computer science?

Computer science focuses on theory and fundamentals; software engineering is concerned with the practicalities of developing and delivering useful software

What is the difference between software engineering and system engineering?

System engineering is concerned with all aspects of computer-based systems development including hardware, software and process engineering. Software engineering is part of this more general process.

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. 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.

Software Products

Tangible output (software) of a software development process

Product Specification

Detailed documents outlining the features, functions, and requirements of a software product. Serves as a blueprint for the development process.

Generic Products

Stand-alone systems that are marketed and sold to any customer who wishes to buy them.

Ex: PC software like graphics programs, project management tools, CAD software, software for specific markets

Generic Product Specification

what the software should do is owned by the software developer and decisions on software change are made by the developer.

Customized Products

Software that is commissioned by a specific customer to meet their own needs.

Ex: embedded control systems, air traffic control software, traffic monitoring systems

Customized Product Specification

what the software should do is owned by the customer for the software and they make decisions on software changes that are required.

Software Engineering Diversity

Many different types of software systems, no universal set of software techniques that are applicable to all of those.

SWE methods and tools depend on type of application being developed, the requirements of the customer, and the background of the development team

Stand-alone Applications

Run on a local computer, such as a PC and do not need to be connected to a network.

Interactive transaction-based applications

Execute on a remote computer and are accessed by users from their own PCs or terminals

Embedded control systems

Control systems that control and manage hardware devices.

Batch Processing Systems

Business systems that are designed to process data in large batches

Entertainment Systems

Systems primarily for personal use and intended to entertain the user.

Systems for Modelling and Simulation

Systems developed by scientists and engineers to model physical processes or situations, which include many, separate, interacting objects

Data Collection Systems

collects data from their environment using sensors and send that data to other systems for processing.

Systems of systems

System composed of several other software systems.

Attributes of Good Software

Maintainability, Dependability and Security, Efficiency, and Acceptability

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

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 utilization, 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

Fundamental Principles

Should be applied to all types of software systems, irrespective of the development techniques used:

1) Develop the system using a managed and understood development process

2) Dependability and performance are important for all types of system

3) Understanding and managing the software specification and requirements are important

4) Reuse software that has already been developed when appropriate instead of writing new code.

Engineering discipline

A mindset for Software Engineering that prioritizes 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.

IEEE's Definition of SWE

The application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software. The application of engineering to software

Bureau of Labor Statistics's Definition of SWE

The systematic application of scientific and technological knowledge, methods, and experience to the design, implementation, testing, and documentation of software

Fritz Bauer's Definition of SWE

The establishment and use of sound engineering principles in order to economically obtain software that is reliable and works efficiently on real machines

Software Specification

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

Categories of Fundamental Activities of SWE

Process Activities and Umbrella Activities

Process Activities

Core development tasks in SWE

Includes: Requirements Gathering & Analysis, Design, Coding, Testing, and Deployment

Umbrella Activities

Support functions in SWE

Includes: Project Management, Configuration Management, Quality Assurance, Documentation, and Software Standards Compliance

Framework Process Activities (FPA)

Communication, Planning, Modeling, Construction, and Deployment

FPA: Communication

Maintain communication channels

FPA: Planning

Defines scope, resources, schedule

FPA: Modeling

Create abstract representation of the system

Analysis of requirements

Design: turn requirements into plans for architecture, components, and interfaces

FPA: Construction

Implement the software design by coding

Code generation: auto code generation from design models

Testing

FPA: Deployment

Delivers software to end user and provide support

Framework Umbrella Activities (FUA)

Software project management

Formal technical reviews

Software quality assurance

Software configuration management

Work product preparation and production

Reusability management

Measurement

Risk management

FUA: Software project management

Planning, organizing, and controlling the software project

FUA: Formal technical reviews

Structured meetings to evaluate software work products

FUA: Software quality assurance

Focuses on establishing and maintaining quality standards throughout the software development process

FUA: Software configuration management

Identifying, controlling, and tracking changes to the software and its associated documentation.

FUA: Work product preparation and production

The activities required to create various work products

FUA: Reusability management

Identifying opportunities to reuse software components

FUA: Measurement

Defining, collecting, and analyzing data about software processes and products

FUA: Risk management

Identifying, assessing, and responding to potential risks that could impact the project's success.

Software Engineering

Focused on building and maintaining software systems.

Applied, practical discipline that emphasizes real-world problem-solving

Delivers functional and efficient software products that meet customer needs

Computer Science

Focused on understanding the theoretical foundation of computation.

Explores computation limits, algorithms and hardware.

Advances computing through research and innovation.

Systems Engineering

Concerned with all components of a system (hardware, software, and user processes)

Key challenges in SWE

Increasing diversity of devices and increasing complexity from new capabilities

Quick responsiveness or delivery of software

Production of trustworthy software

Software Project Failure

When it does not meet defined objectives, within the allocated time and budget.

Can manifest as increasing system complexity and failure to use software engineering methods

General issues that affect software

Heterogeneity, Business and social change, Security and trust, and Scale

Costs of software engineering

Varies, but typically professional software is 60% towards development and 40% towards maintenance

Web's Impact to SWE

Web services, cloud computing, advances to SWE

Advances: programming language, deployment and maintenance techniques, software reuse

Issues of professional responsibility

Confidentiality, Competence, Intellectual property rights, Computer misuse

ACM/IEEE Code of Ethics Principles

Public, Client and Employer, Product, Judgment, Management, Profession, Colleagues, and Self

Insulin Pump: Hardware Architecture

Insulin Pump: Activity Model

MentCare: Organization

Weather Station: Environment

iLearn: Architecture