Introduction to Software Engineering

• Software engineering is achieving sucess through planning, hard work, respect, and paying attention.
• To do well in SE 262, read the relevant textbook portions before each lecture.
• Take notes and ask questions during each lecture.
• Review the lecture slides after each lecture.

Introduction to Software

• Software is a computer program accompanied by documentation and data configuration used in many systems
• Examples of software include mobile apps, autopilot software, embedded software and medical software.
• Software comes in generic and customized forms.
• Generic types are created for any customer.
• Google Chrome and Microsoft Office are generic examples.
• The software developer typically owns what the software should do and makes decisions on changes.
• Custom software is designed for a specific customer.
• Embedded software for Tesla full self-driving is a customized example.
• The customer owns the software specifications and decides on changes.
• Software costs are often higher than computer hardware costs, particularly maintenance.
• Software maintenance costs for long-life systems may be several times the initial development cost.

Importance of Software Engineering

• Many software projects fail due to increasing demand for complex systems and failure to use software engineering methods.
• Individuals and society rely on complex, reliable, trustworthy, economical, and fast software.
• Using software engineering techniques to create software is cheaper in the long run.
• For most systems, the majority of costs are due to changes to the the software requirements after it has already been created.
• Project failures can be attributed to poor requirements definition(50%), inadequate risk management(17%), scope definition(15%) and communication problems(14%) and lack of qualified resources(3%).
• The systematic approach in defining a software project is known as software engineering.

Software Engineering Defined

• Software engineering is an engineering discipline concerned with the theories, methods, and tools for professional and cost-effective software development.
• It manages various aspects of software production from initial specification to user maintenance including project management and tool development.
• A systematic approach concerned with all facets of software production, including specification, development, validation, and evolution
• A software process can be defined with four stages; specification, development, validation and evolution.
• Good software solves problems and makes tasks easier.

Essential Attributes of Good Software

• Functionality: Good software delivers the functionality required to solve problems or make tasks easier.
• Performance: Good software avoids the wasteful use of system resources such as memory and processor cycles.
• Maintainability: Good software evolves to meet the changing needs of customers or business environments.
• Dependability: Good software should not cause physical or economic damage in the event of system failure.
• Acceptability: Good software is understandable, usable, and compatible with other systems.

Software Engineering vs Computer Science

• Computer science concentrates on theory and fundamentals.
• Software Engineering deals with realizing practical applications to meet customers or business needs.

Software Types

• Stand-alone applications run on a local computer and include all necessary functionality without needing a network.
• Interactive applications execute on a remote computer and are accessed by users via their own PCs or terminals.
• Embedded control systems are software systems that control and manage hardware devices.
• Data collection systems gather environmental data using sensors and transmit it to other systems for processing.
• Batch processing systems are the systems designed to process data in large batches.
• Entertainment systems are primarily personal software intended to entertain the user.
• Modeling and simulation systems are developed by scientists and engineers to model physical processes.
• Systems of systems comprise of a number of software systems.

Software Engineering Diversity and Fundamentals

• There is not a universal set of methods and tools for software engineering applicable to all systems; it depends on the software type, the requirements of the customer and the team's background.
• All systems should be developed using managed and understood development processes.
• Dependability and performance are important for all types of systems.
• It is important to understand and manage the software requirements specification (SRS).
• Reuse any software that has already been developed rather than writing new software where appropriate.

Software Engineering and the Web

• The web has become a platform for running applications.
• Web services facilitate application functionality access over the web.
• Cloud computing provides computer services where users pay according to their usage.

General Issues Affecting Most Software

• Today, software often needs to work across many types of devices, like computers and smartphones, that are connected through networks.
• Businesses and societies are changing quickly due to new technologies and the growth of developing countries; software must adapt.
• It is important that all software is safe and reliable.

Software Engineering Ethics

• Software engineers must behave in an honest and ethically responsible way.
• Ethical behavior includes following a set of principles that are morally correct and upholds the law.

Issues of Professional Responsibility

• Confidentiality: Respect the confidentiality of employers or clients, with or without a formal agreement.
• Intellectual property rights include the use of patents and copyrights while ensuring the the intellectual property of employers and clients is protected.
• Competence should never be misrepresented and you should not knowingly accept work which is outside the developers comopetence .
• Computer misuse is anything from computer misuse ranges from relatively trivial (game playing on an employer's machine, say) to extremely serious (dissemination of viruses).

Key Takeaways

• Software engineering is an engineering discipline concerned with aspects of software production.
• Important software product attributes are functionality, performance, maintainability, dependability, and acceptability.
• Fundamental principles and ideas of software engineering are universally applicable to all types of development.
• There are various types of software and each require different software engineering toolsets for development.

Chapter 2 Topics - Software Processes

• Software process activities
• Software process models
• Coping with change

Definition of Software Process

• A set of activities which are needed to develop a software system using software, processes, activites and models.
• A model is a simplified representation of software process activities.

Software Process Description

• Products are the outcome of a software process activity.
• Roles define who is responsible of a software process activity.
• The statements for pre- and post-conditions define if conditions are true before and after a process

Agile and Plan Driven Processes

• Plan driven processes are activities that are planned in advance and progress is measured through the plan.
• Agile processes are incremented so it is easier to reflect changing customer demands.
• Most processes include both agile and plan driven processes in practical applications.
• There are no right or wrong processes.

Software Process Examples

• The waterfall model is an example of processes that are planned, with specification and development in seperate phases.
• The water fall model is most often used for large projects.
• Inflexible project partitioning makes adapting to changing requirements difficult.
• Waterfall models are appropriate when requirements are well understood and changes will be limited during design.
• Incremental development defines development and validation as interleaved.
• Reuse-oriented software engineering integrates existing components or commercial systems.

Incremental Development

• Reduced costs and the amount of redone documentation.
• Easy to get customer feedback for incremental changes.
• Rapid product delivery to the customer is possible, faster than the waterfall method.
• It may not be visible, managers would need deliverables to measure the progress.
• System structure may degrade as new increments are added.
• May be difficult to manage in conjunction with current software.

Reuse-Oriented Software Engineering

• Based on reuse across multiple systems from existing components.
• Key stages include requirements, software evaluation, refinement, configuration and finally integration.
• Reduced costs, faster delivery and reduced risks are achieved.
• There is a loss of control as requirements must meet the current standards.

Software Process Activities

• Software specification defines what the software will be and constraints on its operation.
• Software development defines designed and programmed software.
• Software valiation defines the process which checks the software meets customer requirements.
• Software evolution reflects changes to cater to customers and market requirements.
• Software Specification requires the process of the sub-activity requirement engineering, lead by an Engineer.
• Requirements are gathered and validated from the customers system by a Requirements Engineer.
• A Software Engineer's Architectural design and Interface design is used in combination with different Design outputs such Specifications to make the final software.
• Validation and Verification is achieved through system testing of the system and its components; including unit, system and acceptance testing; using either agile or planned processes
• When making changes, it is important to be as flexible as possible when defining requirements so it does not evolve into chaos

Change Models

There are two change models

• Change avoidance, planning activites with prototype to address changes and future requirements
• Change tolerance, where a incremental based approach can manage lower costs when making changes