What is software?
- Generic - developed to be sold to a range of different customers e.g. PC software such as Excel or Word.
- Bespoke (custom)- developed for a single customer according to their specification.
What is software engineering?
The difference between software engineering and computer science that:-
- Computer science is concerned with theory and fundamentals; software engineering is concerned with the practicalities of developing and delivering useful software.
- Computer science theories are still insufficient to act as a complete underpinning for software engineering (unlike e.g. physics and electrical 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 process concerned with developing the software infrastructure, control, applications and databases in the system.
- System engineers are involved in system specification, architectural design, integration and deployment.
- 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 response to changing demands.
Software Process Model
- Workflow perspective - sequence of activities;
- Data-flow perspective - information flow;
- Role/action perspective - who does what.
- Iterative development
- Component-based software engineering.
Software engineering methods
CASE (Computer-Aided Software Engineering)
CASE systems are often used for method support.
- Tools to support the early process activities of requirements and design;
- Tools to support later activities such as programming, debugging and testing.
Attributes of Good Software
- Maintainability-Software must evolve to meet changing needs
- Dependability-Software must be trustworthy;
- Efficiency-Software should not make wasteful use of system resources;
- Acceptability-Software must accepted by the users for which it was designed. This means it must be understandable, usable and compatible with other systems.
Key Challenges Facing Software Engineering
- Heterogeneity- Developing techniques for building software that can cope with heterogeneous platforms and execution environments;
- Delivery- Developing techniques that lead to faster delivery of software;
- Trust- Developing techniques that demonstrate that software can be trusted by its users.
Professional and ethical responsibility
- Software engineers must behave in an honest and ethically responsible way if they are to be respected as professionals.
- Ethical behaviour is more than simply upholding the law.
- Issues of professional responsibility
- Confidentiality - Engineers should normally respect the confidentiality of their employers or clients irrespective of whether or not a formal confidentiality agreement has been signed.
- Competence - Engineers should not misrepresent their level of competence. They should not knowingly accept work which is outwith their competence.
Issues of professional responsibility
- Engineers should be aware of local laws governing the use of intellectual property such as patents, copyright, etc. They should be careful to ensure that the intellectual property of employers and clients is protected.
- Software engineers should not use their technical skills to misuse other people’s computers. Computer misuse ranges from relatively trivial (game playing on an employer’s machine, say) to extremely serious (dissemination of viruses).
ACM/IEEE Code of Ethics
The Code contains eight Principles related to the behaviour 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. This code of ethics consists of:-
- 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:
- Software engineers shall act consistently with the public interest.
- Software engineers shall act in a manner that is in the best interests of their client and employer consistent with the public interest.
- Software engineers shall ensure that their products and related modifications meet the highest professional standards possible.
- Software engineers shall maintain integrity and independence in their professional judgment.
- Software engineering managers and leaders shall subscribe to and promote an ethical approach to the management of software development and maintenance.
- Software engineers shall advance the integrity and reputation of the profession consistent with the public interest.
- Software engineers shall be fair to and supportive of their colleagues.
- Software engineers shall participate in lifelong learning regarding the practice of their profession and shall promote an ethical approach to the practice of the profession.
This is the disagreement in principle with the policies of senior management, eg an employer acts in an unethical way and releases a safety-critical system without finishing the testing of the system or Participation in the development of military weapons systems or nuclear systems.
- Software engineering is an engineering discipline that is concerned with all aspects of software production.
- Software products consist of developed programs and associated documentation. Essential product attributes are maintainability, dependability, efficiency and usability.
- The software process consists of activities that are involved in developing software products. Basic activities are software specification, development, validation and evolution.
- Methods are organised ways of producing software. They include suggestions for the process to be followed, the notations to be used, rules governing the system descriptions which are produced and design guidelines.
- Key points
- CASE tools are software systems which are designed to support routine activities in the software process such as editing design diagrams, checking diagram consistency and keeping track of program tests which have been run.
- Software engineers have responsibilities to the engineering profession and society. They should not simply be concerned with technical issues.
- Professional societies publish codes of conduct which set out the standards of behaviour expected of their members.