Introduction to Software Engineering Attributes of Software-Intensive Systems Software Engineering Definitions Software Engineering as a Process Software Engineering Challenges Professional Responsibilities of Software Engineers 9/19/2018 Kal Toth, Oregon State University, Software Engineering

Software-Intensive Systems Large Numbers (100s, 1000s, millions) of: Users Developers Lines of code Pages of User Documentation and help screens Pages of Requirements and Design Documentation Customers: Governments, Businesses, Individuals 9/19/2018 Kal Toth, Oregon State University, Software Engineering

Software-Intensive Systems Implementation involves distributed objects, database systems, web servers. Portable across multiple platforms. Requirements and specifications obtained through extensive interviews, prototypes, and participant research. Detailed test plan with automated testing. Project requires 1-2 years. System will evolve for 20 years after initial installation. 9/19/2018 Kal Toth, Oregon State University, Software Engineering

FAQs about software engineering What is software? What is software engineering? What is the difference between software engineering and computer science? What is the difference between software engineering and system engineering? What is a software process? What is a software process model? 9/19/2018 Kal Toth, Oregon State University, Software Engineering

FAQs about software engineering What are the costs of software engineering? What is CASE (Computer-Aided Software Engineering) What are the attributes of good software? What are the key challenges facing software engineering? 9/19/2018 Kal Toth, Oregon State University, Software Engineering

Kal Toth, Oregon State University, Software Engineering What is software? Computer programs and associated documentation, installation and un-installation scripts, etc. Software products may be Generic - developed to be sold to a range of different customers Custom - developed for a single customer according to their specification 9/19/2018 Kal Toth, Oregon State University, Software Engineering

What is software engineering? A set of methods for the cost-efficient development and evolution of software systems. Issues, techniques, and lessons learned from previous software projects. Methods for acquiring and debugging requirements. Methods for refining and debugging specifications. Representations and languages for communicating with other software engineers. Methods for project management (costing and scheduling). A typical software engineer will only work on about 20 projects in his/her career. That doesn’t provide much opportunity to learn from experience. Need to study the experiences of other software engineers. 9/19/2018 Kal Toth, Oregon State University, Software Engineering

Kal Toth, Oregon State University, Software Engineering What is the difference between software engineering and computer science? Software engineering requires skills and knowledge from computer science, but also from management, speech communications, and writing. Computer science is concerned with the development of theory and technology. Software engineers apply this technology, but sometimes they stumble upon new problems that have not yet been formally studied by computer scientists. Real-world software projects are an important source of new problems for computer science. 9/19/2018 Kal Toth, Oregon State University, Software Engineering

Kal Toth, Oregon State University, Software Engineering 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 process System engineers are involved in system specification, architectural design, integration and deployment 9/19/2018 Kal Toth, Oregon State University, Software Engineering

What is a software process? A set of activities whose goal is the development or evolution of software Generic activities in all software processes are: 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 9/19/2018 Kal Toth, Oregon State University, Software Engineering

What is a software process model? A simplified representation of a software process, presented from a specific perspective Examples of process perspectives are Workflow perspective - sequence of activities Data-flow perspective - information flow Role/action perspective - who does what Generic process models Waterfall Evolutionary development Formal transformation Integration from reusable components 9/19/2018 Kal Toth, Oregon State University, Software Engineering

Kal Toth, Oregon State University, Software Engineering What are the costs? Replace this with details from the text. 9/19/2018 Kal Toth, Oregon State University, Software Engineering

Kal Toth, Oregon State University, Software Engineering Development Costs 9/19/2018 Kal Toth, Oregon State University, Software Engineering

Kal Toth, Oregon State University, Software Engineering Lessons Most important goal: Reduce testing and evolution costs Get the requirements right! Coding is a small part of the software development cost. 9/19/2018 Kal Toth, Oregon State University, Software Engineering

Computer-Aided Software Engineering? Software systems which are intended to provide automated support for software process activities. CASE systems are often used for method support Upper-CASE Tools to support the early process activities of requirements and design Lower-CASE Tools to support later activities such as programming, debugging and testing 9/19/2018 Kal Toth, Oregon State University, Software Engineering

Attributes of good software? Deliver the required functionality and performance to the user. Maintainability Software must evolve to meet changing needs Dependability Software must be trustworthy Efficiency Software should not make wasteful use of system resources Usability Software must be usable by the users for which it was designed 9/19/2018 Kal Toth, Oregon State University, Software Engineering

What are the key challenges facing software engineering? Coping with legacy systems, coping with increasing diversity, and coping with demands for reduced delivery times Legacy systems Old, valuable systems must be maintained and updated Heterogeneity Systems are distributed and include a mix of hardware and software Delivery There is increasing pressure for faster delivery of software 9/19/2018 Kal Toth, Oregon State University, Software Engineering

Professional and ethical responsibility Software engineering involves wider responsibilities than simply the application of technical skills Software engineers must behave in an honest and ethically responsible way if they are to be respected as professionals Ethical behavior is more than simply upholding the law. 9/19/2018 Kal Toth, Oregon State University, Software Engineering

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 beyond their competence. 9/19/2018 Kal Toth, Oregon State University, Software Engineering

Issues of professional responsibility Intellectual property rights 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. Computer misuse 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). 9/19/2018 Kal Toth, Oregon State University, Software Engineering

ACM/IEEE Code of Ethics The professional societies in the US have cooperated to produce a code of ethical practice. Members of these organisations sign up to the code of practice when they join. The Code contains eight Principles related to the behavior 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. 9/19/2018 Kal Toth, Oregon State University, Software Engineering

Code of ethics - principles 1. PUBLIC Software engineers shall act consistently with the public interest. 2. CLIENT AND EMPLOYER Software engineers shall act in a manner that is in the best interests of their client and employer consistent with the public interest. 3. PRODUCT Software engineers shall ensure that their products and related modifications meet the highest professional standards possible. 9/19/2018 Kal Toth, Oregon State University, Software Engineering

Code of ethics - principles 4. JUDGMENT Software engineers shall maintain integrity and independence in their professional judgment. 5. MANAGEMENT Software engineering managers and leaders shall subscribe to and promote an ethical approach to the management of software development and maintenance. 6. PROFESSION Software engineers shall advance the integrity and reputation of the profession consistent with the public interest. 9/19/2018 Kal Toth, Oregon State University, Software Engineering

Code of ethics - principles 7. COLLEAGUES Software engineers shall be fair to and supportive of their colleagues. 8. SELF 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. 9/19/2018 Kal Toth, Oregon State University, Software Engineering

Kal Toth, Oregon State University, Software Engineering Ethical dilemmas Disagreement in principle with the policies of senior management Your employer acts in an unethical way and releases a safety-critical system without finishing the testing of the system Participation in the development of systems that have clear potential for harm as well as good (e.g., unbreakable encryption, eavesdropping and profiling tools, weapons systems) 9/19/2018 Kal Toth, Oregon State University, Software Engineering

Kal Toth, Oregon State University, Software Engineering Conclusion Systems engineering is hard! There will never be an easy answer to the problems of complex system development Software engineers do not have all the answers but may be better at taking a systems viewpoint Disciplines need to recognize each others strengths and actively rather than reluctantly cooperate in the systems engineering process 9/19/2018 Kal Toth, Oregon State University, Software Engineering