CSCC40 Analysis and Design of Information Systems These lecture slides are provided for the personal use of students taking CSCC40 in the Fall term of 2007 at the University of Toronto. Copying for purposes other than this use, and all forms of distribution are expressly prohibited. Some slides are adapted from the course textbook: Object-Oriented Systems Analysis and Design Using UML. 3rd ed. Bennett, McRobb, Farmer. McGraw-Hill. 2002. The following sources of information are also recommended Project Management Institute Association of Computing Machinery IEEE Computer Society

these topics are covered in ACM computing curricula 2001 software engineering processes requirements and specifications design validation delivery of systems evolution project management tools and environments component-based computing formal methods reliability these topics are covered in CSCC40 and CSCD08

value chain

missions, strategies and their realization drives and sets goals business strategy where IT can help what must be done information systems strategy hardware capabilities informs and enables system requirements information technology strategy Fig. 1.10 the relationship between business, IS and IT strategies

all systems (manual and/or automated) have these characteristics what the system does how the system is controlled inputs outputs control feed-forward feedback system boundary

types of systems transaction processing systems management information systems decision support systems expert systems real-time (control) systems other each can be implemented as online and/or batch distributed and/or centralized corporate and/or departmental and/or public

the three perspectives technological hardware, networks, databases, CASE tools ... social how do individuals and organizations use information, how are they affected by technology… professional practices and standards, policies, quality practices ...

hardware software communication personal computers, workstations, mainframes, hardware components, CPUs, memory, disks, peripherals palmtops ... word processing, spreadsheets, presentation software, website design, web search engines, document management CASE tools ... hardware software communication e-mail, fax, wireless communication, telephone, networks, internet ... technologies for analysis and design

functional decomposition of business Hoffer, George, Valacich. Modern Systems Analysis and Design. 2nd ed. Addison Welsey 1999. functional decomposition of business business function supporting function

typical suite of systems

decomposition of a business system

conceptual complexity ! Where does one system end, and another start? If a system is a subjective view of reality, then who’s view do we work with? How do we cope when: the system is too large to be understood by any one person? technology is changing all the time? user requirements are changing all the time? new development tools and techniques and methodologies are constantly needed?

we have coping strategies ! methodologies: waterfall, prototype, extreme . . . time-tested techniques for: verification, validation, estimating . . . abstraction and decomposition modeling methods: structured, object-oriented . . . tools for: project control, design control, configuration management . . .

what we want to avoid / prevent ... from end user’s perspective ... What system? I haven’t seen a new system. (vaporware) It might work, but it’s dreadful to use. (lots of reasons) It’s pretty, but does it do anything useful? (not an improvement) from client’s perspective ... If I’d known the real price, I’d never have agreed. It’s no use delivering it now –we needed it last April. OK, so it works, but the installation was such a mess, my staff will never trust it. I didn’t want it in the first place. Everything’s changed now –we need a completely different system.

what we want to avoid / prevent ... from the developer’s perspective ... We built what they said they wanted. There wasn’t enough time to do it any better. Don’t blame me –I’ve never done O-O analysis before. How can I fix it –I don’t know how it’s supposed to work. We said it was impossible, but no-one listened. The system’s fine –the users are the problem.