Software Types: Custom, Generic, Embedded

What is Software?

• Software comprises computer programs, procedures, rules, associated documentation, and data.
• Custom or Bespoke software is designed for a specific customer's unique needs.
  • Examples: websites, air traffic control systems
• Generic software, often called Commercial Off The Shelf (COTS) or shrink-wrapped and is sold on the open market.
  • Examples: word processors, spreadsheets, compilers
• Embedded software is built into hardware, making it difficult to change.

Types of Software

• Real-time software is used in critical applications where timely responses are crucial.
  • Examples include industrial automation, aerospace systems, medical devices, telecommunications, and financial trading systems.
  • Most embedded systems operate under hard real-time constraints.
• Data processing software runs businesses.
  • Key concerns are accuracy and security of data.
  • It carries out functions like recording sales, managing accounts, and printing bills.

Software Engineering Defined

• Software engineering is a discipline focused on the design, development, testing, and maintenance of software systems.
• The discipline encompasses requirement analysis, design, coding, testing, and deployment.
• Methodologies, tools, and practices aim to produce high-quality software meeting user and stakeholder needs.
• It solves customer problems through systematic development and evolution of large, high-quality software systems within cost, time, and other constraints.
• It involves all aspects of software production, from initial system specification to ongoing maintenance after deployment.
• It applies appropriate theories and methods to address problems, considering organizational and financial constraints.
• It includes project management and the development of tools and methods to support software production.

Key Aspects of Software Engineering

• The main goal of software engineering is solving customer problems.
• Sometimes buying a solution is better than building it.
• Adding unnecessary features doesn't help solve the problem.
• Effective communication is essential for software engineers to identify and understand problems.
• Systematic development applies established techniques in an organized and disciplined way.
• Many software engineering practices have been formally standardized by organizations like the IEEE or ISO.
• Most development work involves evolution of existing systems.
• Software engineering techniques are vital because large systems are too complex for one person to fully grasp.
• Teamwork and coordination are therefore essential.
• A key challenge is dividing work properly and ensuring all parts of the system function together.
• The final product must meet sufficient quality standards.
• Projects operate under finite resources, so benefits must outweigh costs.
• Inaccurate time and cost estimates are a common cause of project failure.
• There is often competition to provide solutions faster and more affordably.

Essential Software Attributes

• Maintainability: Software should evolve to meet users' changing needs; adapting to change is critical.
• Dependability and Security: Characteristics including reliability, security, and safety; software should not cause physical or economic harm and must withstand malicious access.
• Efficiency: Software should use resources wisely, including responsiveness, processing time, and memory.
• Acceptability: Software must be understandable, usable, and compatible for its intended users.

Software Costs

• Software costs usually dominate those of entire computer systems.
• Software costs on a PC often exceed hardware costs.
• Software costs are higher for maintenance than for development.
• For long-term systems, maintenance costs can significantly outweigh development costs.
• Software engineering prioritizes cost-effective software development.

Software Maintenance

• It involves modifying a program after it’s been put into use.
• This term often applies to custom software modifications.
• Generic software products change to create new versions.
• It usually doesn’t encompass extensive changes to the system’s architecture.
• It uses changes implemented by modifying or adding components to the system.
• Software faults are repaired by changing a system to correct deficiencies.
• Maintenance, to adapt, ensures operation in alternative environments (OS, computer, etc.).
• Functionality can be added to, or modified.
• The system is adapted to satisfy new requirements.
• Functionality addition or modification accounts for 65% of maintenance efforts.
• Environmental adaptation makes up 18% of maintenance efforts.
• Fault repair makes up 17% of maintenance efforts.
• Costs are generally greater than those of development, potentially ranging from two to one hundred times the development costs, based on application.
• Technical and non-technical factors affect costs.
• Costs increase so the software is maintained over time.
• Maintenance degrades software structure, making it more difficult.
• Ageing software can result in high support costs (e.g. old languages, compilers).
• Team stability reduces costs when the same staff members are involved long-term.
• Contractual issues can determine change incentives.
• Limited staff skills can impact maintenance.
• Older programs often degrade making them harder to change.

General Issues Affecting Software

• Increasing heterogeneity requires systems to work across varied networks, devices etc.
• Rapid social and business changes require software to adapt quickly.
• Trust in software is essential.

Software Engineering Fundamentals

• Always use a managed and fully understood development process when building systems.
• Use different processes for different types of software.
• Dependability and performance are key.
• Understanding/ managing the software specification is important for fulfilling goals.
• Reuse software when possible, rather than writing new code.

Software Engineering and the Web

• The web has become a platform for running applications and organizations are increasingly developing web-based systems instead of local ones.
• Web services provide application functionality accessible over the web.
• Cloud computing provides computer services with applications running remotely.
• Users pay according to their usage.
• Software reuse is the dominant approach to build web systems.
• A focus on pre-existing software components informs construction.
• Web systems should be developed and delivered incrementally.
• It’s impractical to define all requirements in advance.
• User interfaces are limited by the abilities of web browsers.
• AJAX can create feature-rich interfaces.
• Local scripting and web forms are more prevalently used.

Software Development Types

• Front-End Development: User interface creation using HTML, CSS, and JavaScript.
• Back-End Development: Server-side operations and data handling, often programmed with Python, Java, or Node.js.
• Full-Stack Development: Combine front and back-end skills for comprehensive web development.

Professional Responsibilities

• Confidentiality: Respect employer and client confidentiality, per signed agreements.
• competence: accurately represent skill level and not accept work outside this level.
• Intellectual Property Rights: Awareness of local laws and protecting employer/client IP.
• Computer Misuse: Do not misuse technical expertise to harm others' systems.
• Act with integrity.
• Software engineers have to be fair and supportive to their colleagues.
• Participate in lifelong learning.
• Must behave in a honest and ethically responsible way if they are to be respected.
• This extends past the law and the the moral responsibilities of the practice.
• Act with honesty, integrity, and fairness in all business and professional dealings.
• Developing and designing software with consideration for users.
• Privacy, safety and well being of the end user is paramount.
• Take responsibility for one's actions.

Ethical Principles in Software Engineering

• Act consistently with the public interest.
• Act in a manner that is in the best interests of their client and employer.
• Ensure that their products and related modifications meet the highest professional standards.
• Maintain integrity and independence in their professional judgment.
• Promote an ethical approach to management of development and maintenance.
• Advance the integrity and reputation of the profession.
• Act in the best interests of their clients.
• Maintain integrity and independence.

Ethical Dilemmas

• Disagreement: Differing viewpoints in principle over the policies of senior management.
• Unethical action: Releasing safety-critical system is done unethically without finishing testing.
• Participate in military weapon or nuclear system development.