Software Engineering Principles

Software Engineering Introduction

• Software engineering is a field focused on theories, methods, and tools for professional software development.
• All developed nations rely heavily on software.
• Software costs often exceed hardware costs, and maintenance costs are frequently multiples of development costs.
• Software engineering prioritizes cost-effective development.

Topics Covered

• Software and Software Engineering
• Software Engineering Ethics

Software Project Failure

• Increasing system complexity makes demands for larger and more complex software systems, which can be challenging and even impossible.
• Many companies skip software engineering for quicker development, causing higher costs and lower reliability.

Software Products

• Generic products are marketed to multiple customers, examples include general PC software.
• Customized products are tailored to meet a specific customer's needs, examples include embedded control systems such as air traffic control.

Product Specification

• For generic products, the software developer defines the specification and makes changes.
• For customized products, the customer defines the specification and makes decisions about changes.

Essential Attributes of Good Software

• Maintainability: The software must be able to adapt to changing customer needs.
• Dependability and Security: The software must be reliable, with no damage to users or systems.
• Efficiency: Software should not use excessive resources like memory and processing power.
• Acceptability: The software must be user-friendly and compatible with other systems.

Software Engineering

• Software engineering is a discipline concerned with all aspects of software production, from initial design to ongoing maintenance.
• It relies on appropriate theories and methods to solve problems, considering organizational and financial constraints.
• It's not just development; it also includes project management and tools development to support the overall process.

Importance of Software Engineering

• Individuals and society rely heavily on advanced software systems, demanding reliable and economical software creation.
• Software engineering methodologies are generally more cost-effective for system development in the long run than ad-hoc methods.

Software Process Activities

• Software Specification: Customers and engineers define the software and its operational constraints.
• Software Development: The software is designed and programmed.
• Software Validation: The software is checked and verified to meet customer requirements.
• Software Evolution: Software is modified to reflect changing customer and market needs.

General Issues Affecting Software

• Heterogeneity: Systems are often distributed across different networks and devices (computers, mobiles).
• Business and Social Change: Business and society change quickly, requiring the ability to modify and develop new software.
• Security and Trust: Software must be reliable and trusted to ensure safety.
• Scale: Software must operate across a range of sizes from simple to global systems.

Software Engineering Diversity

• Different types of software systems exist. There's no universal method for all software.
• The best approaches depend on application type, customer needs, and development team expertise.

Application Types

• Stand-alone: Runs on a local computer.
• Interactive Transaction-Based: Runs on a remote computer, accessed by PCs and terminals (e.g., e-commerce).
• Embedded Control: Controls hardware (e.g., air traffic control).
• Batch Processing: Processes large batches of data.
• Entertainment: Designed for personal entertainment.
• Modeling and Simulation: Used for modeling and testing physical processes.
• Data Collection Systems: Collect data using sensors.
• Systems of Systems: Sophisticated systems combining numerous components.

Software Engineering Fundamentals

• Principles apply to all software systems, regardless of the development method.
• Developing processes should be managed and understood.
• Dependability and performance are essential.
• Software specification and requirements must be understood and well-managed.

Internet Software Engineering

• The Web is the most used software platform.
• Web-based development is a major focus.
• Web Services allow access over the web.
• Cloud is a method for providing remote computer and application services.

Web-based Software Engineering

• Web systems are complex but still follow the same fundamental principles as other software systems.
• Fundamental software engineering ideas are applied to web-based software similarly to other applications.

Web Software Engineering

• Software reuse is the dominant approach for web development.
• Incremental and agile development models are common.
• Service-oriented systems, AJAX, and HTML5 technologies are used to support richer web interfaces.

Software Engineering Ethics

• Software engineering has wider responsibilities than just technical skills.
• Engineers must act honestly and ethically.
• Ethical behavior goes beyond following laws and includes moral principles.

Issues of Professional Responsibility

• Confidentiality: Respecting the confidentiality of clients and employers.
• Competence: Not misrepresenting skills and accepting projects beyond one's ability.
• Intellectual Property: Respecting copyright and patent laws to maintain data security.
• Computer Misuse: Not using skills to misuse others' computers.

ACM/IEEE Code of Ethics

• Professional societies in the US have a code of ethics.
• Members agree to follow the code after joining.
• The code has principles for software engineers at various stages and roles within the profession.

Rationale for the Code of Ethics

• Software engineers impact numerous parts of society and have opportunities to do good or cause harm.
• Engineers should commit to making software engineering a positive and respected profession.

ACM/IEEE Code of Ethics

• Aspiration and detail are part of the code; they need to be considered together
• Software engineers are responsible for making software systems a benefit to society, and to protect intellectual property and be well-behaved

Ethical Principles

• Public Interest: Act consistently in the public's benefit.
• Client and Employer: Act in client and employer best interest.
• Product: Develop high-quality products.
• Professional Judgment: Make sound, unbiased judgments.
• Management: Manage software development ethically and effectively.
• Profession: Advance professionalism within the field.
• Colleagues: Support and be fair to co-workers.
• Self: Continuously improve skills and encourage ethics throughout the profession.

Ethical Dilemmas

• Disagreements with management policies.
• Unethical employer actions, such as releasing untested software.
• Participating in the development of controversial systems like military weapons or nuclear systems.