Software Engineering - Lecture Slides | CMSC 435, Exams of Software Engineering

Download Software Engineering - Lecture Slides | CMSC 435 and more Exams Software Engineering in PDF only on Docsity! CMSC 435 - 1 CMSC 435: Software Engineering Course overview CMSC 435 - 2 Topics covered today ● Course requirements ● FAQs about software engineering ● Professional and ethical responsibility CMSC 435 - 3 Course Objectives ● To introduce software engineering and to explain its importance in building large programs ● To understand the process of developing new technology and the role of experimentation ● To set out the answers to key questions about software engineering ● To introduce ethical and professional issues and to explain why they are of concern to software engineers CMSC 435 - 4 CMSC 435 requirements ● Exam 1 (20%) and Exam 2 (20%) ● Project (40%) ● Report (10%) ● Other (homework, presentations, …) (10%) ● Project goal is to take a large system and add several features to it:
System is a prototype of an FAA air traffic control system called TSAFE.
You have to make decisions on the implementation and test your results
Projects are group activities; system written in Java.
For EACH phase of the project you will be in a different group, randomly assigned ● Use class website. (www.cs.umd.edu/~mvz/cmsc435-s09/) CMSC 435 - 9 Two aspect of Software Engineering: Synthesis SOLUTION Solution 1 Solution 3 Solution 2 Solution 4 CMSC 435 - 10 Software costs ● Software costs often dominate computer system costs. The costs of software on a PC are always greater than the hardware cost. ● Software costs more to maintain than it does to develop. For systems with a long life, maintenance costs may be several times development costs. ● Software engineering is concerned with cost- effective software development. CMSC 435 - 11 Why is it 435 and not 135? ● Need experience is building big programs. (435 is not a programming course.) Learn how to work in groups. ● Every student starts Computer Science 1 “knowing” everything. Previous generations had problems only because they were too sloppy or not smart enough. ● You have to experience the 4am panic to finish a project due 8am to really understand the problems with software development. ● By now you should understand that there MUST be a better way to do this. CMSC 435 - 12 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? CMSC 435 - 13 FAQs about software engineering ● What are the costs of software engineering? ● What are software engineering methods? ● What is CASE (Computer-Aided Software Engineering) ● What are the attributes of good software? ● What are the key challenges facing software engineering? CMSC 435 - 14 What is software? ● Computer programs and associated documentation such as requirements, design models and user manuals. ● Software products may be developed for a particular customer or may be developed for a general market. ● Software products may be
Generic - developed to be sold to a range of different customers e.g. PC software such as Excel or Word.
Custom - developed for a single customer according to their specification. ● New software can be created by developing new programs, configuring generic software systems or reusing existing software. (Reuse is emphasis this semester) CMSC 435 - 19 Typical development processes . Requirements engineering • System analysis • High-level design/architecture • Low-level design • Coding • Integration • Design and code reviews • Testing • Maintenance • Project management • Configuration management CMSC 435 - 20 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;
Iterative development;
Agile development;
Component-based software engineering. CMSC 435 - 21 What are the costs of software engineering? ● Roughly 60% of costs are development costs, 40% are testing costs. For custom software, evolution costs often exceed development costs. ● Costs vary depending on the type of system being developed and the requirements of system attributes such as performance and system reliability. ● Distribution of costs depends on the development model that is used. CMSC 435 - 22 Activity cost distribution Product development CMSC 435 - 23 What are software engineering methods? ● Structured approaches to software development which include system models, notations, rules, design advice and process guidance. ● Model descriptions
Descriptions of graphical models which should be produced; ● Rules
Constraints applied to system models; ● Recommendations
Advice on good design practice; ● Process guidance
What activities to follow. CMSC 435 - 24 What is CASE (Computer-Aided Software Engineering) ● Software systems that are intended to provide automated support for software process activities. ● CASE systems are often used for method support. ● Upper-CASE (“Upstream”)
Tools to support the early process activities of requirements and design; ● Lower-CASE (“Downstream”)
Tools to support later activities such as programming, debugging and testing. CMSC 435 - 29 Programming Software Engineering Specification Design Code Test 1. Use of correct tools for each process 2. Extend to other processes Economics Requirements Acceptance test Management Risk CMSC 435 - 30 What attributes are new in 435? ● What is different about these attributes from projects developed in earlier courses?
Economics – Can I build it on time and within budget?
Risk – What can happen and how likely is it for project completion not on time or within budget?
Management – How to manage and schedule people for most efficient and effective utilization of them CMSC 435 - 31 Programming Systems extend to entire life cycle of product ● Problem: Program to read in a rational number and compute its square root. ● Programming solution: A relatively small program in some programming language. ● Programming system: • Source program in some language • Executable file for common platforms • Installation script to install on various platforms • Documentation of requirements • Documentation of design • Error messages and corrective action • Timing and performance data • Users guide • Test data • Help system to fix errors Turn in this programming system on Thursday, February 5th CMSC 435 - 32 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. CMSC 435 - 33 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.
Issue: Should software engineers be licensed? What does competence really mean here? CMSC 435 - 34 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).