1© Easterbrook 2004-51University of TorontoDepartment of Computer ScienceCSC340:Requirements EngineeringProf Steve [email protected]://www.cs.toronto.edu/~sme/CSC340FUniversity of TorontoDepartment of Computer Science© Easterbrook 2004-52About the Course Course website www.cs.toronto.edu/~sme/CSC340F/ Textbooks Fundamentals of Requirements Engineering UML Distilled Lecture Notes Available on the course website prior to each lecture Coursework Carried out in teams of 3 Each team submits one report (per assignment) All team members receive the same grade (exceptions can be negotiated) Involves a practical “real-world” analysis projectUniversity of TorontoDepartment of Computer Science© Easterbrook 2004-53Course Objectives Examine the state-of-the-art for research &practice in Requirements Engineering. Role of RE in software and systems engineering Current techniques, notations, methods, processes and tools used in RE Gain practical experience in selected RE techniques Especially goal-oriented and object-oriented modelling techniques Understand the essential nature of RE Breadth of skills needed for RE, and the many disciplines on which it draws Contextual factors & practicalitiesUniversity of TorontoDepartment of Computer Science© Easterbrook 2004-54Assessment 4 team assignments:1. Conduct an inspection of an existing specification (10%) Report on defects found, overall quality, and inspection stats2. Perform a feasibility study for an information systems project (15%) Write a feasibility report3. Perform a requirements analysis for the same project (10%) Produce models that explain the problem4. Specify the requirements for the same project (10%) Write a requirements specification 2 tests: Midterm test (20%) Final Exam (35%) Must obtain at least 40% on this exam to pass the course.2University of TorontoDepartment of Computer Science© Easterbrook 2004-55Course Policies Assignment Deadlines Are very strict (use a U of T medical certificate if you are seriously ill) Assignments are due in the first 10 minutes of a tutorial Daily penalties apply to late work Re-grading Will only be done by the professor (TAs will not re-grade your work) The whole report will be re-graded (not just individual sections) Your mark may go up or down Communication TAs and instructor will not answer any queries related to the assignments inthe 24 hour period prior to the deadline Announcements will appear on the course website. Please check it regularly.University of TorontoDepartment of Computer Science© Easterbrook 2004-56Software-Intensive Systems Software (on its own) is useless Software is an abstract description of a set of computations Software only becomes useful when run on some hardware we sometimes take the hardware for granted Software + Hardware = “Computer System” A Computer System (on its own) is useless Only useful in the context of some human activity that it can support we sometimes take the human context for granted A new computer system will change human activities in significant ways Software + Hardware + Human Activities = “Software-Intensive System” ‘Software’ makes many things possible It is complex and adaptable It can be rapidly changed on-the-fly It turns general-purpose hardware into a huge variety of useful machinesUniversity of TorontoDepartment of Computer Science© Easterbrook 2004-57Quality = Fitness for purpose Software technology is everywhere Affects nearly all aspects of our lives But our experience of software technology is often frustrating/disappointing Software is designed for a purpose If it doesn’t work well then either: …the designer didn’t have an adequate understanding of the purpose …or we are using the software for a purpose different from the intended one Requirements analysis is about identifying this purpose Inadequate understanding of the purpose leads to poor quality software The purpose is found in human activities E.g. Purpose of a banking system comes from the business activities ofbanks and the needs of their customers The purpose is often complex: Many different kinds of people and activities Conflicting interests among themUniversity of TorontoDepartment of Computer Science© Easterbrook 2004-58Where are the challenges?Application Domain Machine Domain3University of TorontoDepartment of Computer Science© Easterbrook 2004-59Complexity of Purpose People and software are closely-coupled Complex modes of interaction Long duration of interaction Mixed-initiative interaction Socially-situated interaction …software systems and human activity shape each other in complex ways The problems we’d like software to solve are “wicked” No definitive formulation of the problem No stopping rule (each solution leads to new insights) Solutions are not right or wrong No objective test of how good a solution is (subjective judgment needed) Each problem is unique (no other problem is exactly like it) Each problem can be treated as a symptom of another problem Problems often have strong political, ethical or professional dimensionsUniversity of TorontoDepartment of Computer Science© Easterbrook 2004-510Dealing with problem complexity Abstraction Ignore detail to see the big picture Treat objects as the same by ignoring certain differences (beware: every abstraction involves choice over what is important) Decomposition Partition a problem into independent pieces, to study separately (beware: the parts are rarely independent really) Projection Separate different concerns (views) and describe them separately Different from decomposition as it does not partition the problem space (beware: different views will be inconsistent most of the time) Modularization Choose structures that are stable over time, to localize change (beware: any structure will make some changes easier and others harder)University of TorontoDepartment of Computer Science© Easterbrook 2004-511Designing for people What is the real goal of software design? Creating new programs, components, algorithms, user interfaces,…? Making human activities more effective, efficient, safe, enjoyable,…? How rational is the design process? Hard systems view:
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