Introduction to Systems Analysis and Design CIS 4800 Kannan Mohan Department of CIS Zicklin School of Business, Baruch College Copyright © 2009 John Wiley & Sons, Inc. Copyright © 2009 Kannan Mohan

Learning Objectives Explain the importance of analysis and design Explain the phases in the systems development life cycle Explain the role of Unified Modeling Language and Unified Process in systems development

Software Woes… 1983: F16 autopilot flipped plane upside down whenever it crossed the equator 1985: Arthritis-therapy microwave set patient’s heart pacemaker to 214, resulting in fatal coronary 1987: NORAD defense radar system mistook the Moon for a hostile incoming missile

Software Woes… 1988: Bank of America – Spent $ 23 Million on MasterNet – A computerized accounting and reporting system – Spent another $ 60 million to make it work and finally gave up – Lost billions of dollars of customer accounts

Software Woes… 1990: Vancouver Stock exchange index rose 50% when 2 years of round-off errors in the program were corrected 1992: “Compatible” teller machines of 2 British banks handled leap years differently, withholding cash and confiscating cards during New Year Holiday

Recent Significant IT Failures

Why Should We Care? Would you buy a car that only had a 28% chance of driving off the lot with no problems?

Software Project Success Rate (Emam et al, 2008)

Reasons for Project Cancellation Senior management not sufficiently involved Too many requirements and scope changes Lack of necessary management skills Over budget Lack of necessary technical skills (Emam et al, 2008)

Reasons for Project Cancellation (Contd.) No more need for the system to be developed Over schedule Technology too new; didn’t work as expected Insufficient staff Critical quality problems with software End users not sufficiently involved (Emam et al, 2008)

Systems Development Life Cycle

SDLC: Planning 1.Project Initiation – Develop a system request – Conduct a feasibility analysis 2.Project Management – Develop work plan – Staff the project – Control and direct the project Why should we build this system?

SDLC: Analysis 1.Develop analysis strategy 2.Gather requirements 3.Develop a system proposal What should the system do for us? Where and when will it be used?

SDLC: Design 1.Develop a design strategy 2.Design architecture and interfaces 3.Develop databases and file specifications 4.Develop the program design How will we build the system?

SDLC: Implementation 1.Construct system 2.Install system – Implement a training plan for the users 3.Establish a support plan Build the system!

Putting the SDLC Together Each phase consists of steps that lead to specific deliverables The system evolves through gradual refinement Once the system is implemented, it may go back into a planning phase for its next revision, a follow-on system, or maintenance releases

Processes and Deliverables

Systems Development Methodologies A methodology is a formalized approach to implementing the SDLC Well-known methodologies include: – Waterfall development – Prototyping – Agile development

Waterfall Development

Prototyping

Agile Development Extreme Programming (Beck, 1999)

Software Development Life Cycle Costs

Cost of Fixing Problems

Software Faults

Selecting the Right Methodology Usefulness for WaterfallPrototypingThrowaway Prototyping Extreme Programming Unclear user requirements PoorExcellent Unfamiliar technology Poor ExcellentPoor Complex systems GoodPoorExcellentPoor Reliable systems GoodPoorExcellentGood Short time schedule PoorExcellentGoodExcellent Schedule visibility PoorExcellentGood

Process What, when, who, and how? From requirements to software Unified Modeling Language - A visual language Unified Process - A process New or changed requirements New or changed system Software Engineering Process

The Unified Process (IBM RUP)

The Unified Process A two-dimensional process framework consisting of phases and flows – Phases describe how the system evolves over time – Workflows are collections of tasks that occur throughout the lifecycle, but vary in intensity

What is UML? Unified Modeling Language General purpose visual modeling language Not a methodology or a process Industry standard Approved by Object Management Group (OMG)

Unified Modeling Language Provides a common vocabulary of object- oriented terms and diagramming techniques rich enough to model any systems development project from analysis through implementation Version 2.0 has 14 diagrams in 2 major groups: – Structure diagrams – Behavior diagrams

History of UML Unifying past approaches – Booch method – Object Management Technique (OMT) by Rumbaugh Evolving – Changes in profile – Latest is UML specification 2.0

Nature of Specification How formal? – UML as a – Sketch Blueprint Executable Model Driven Architecture (MDA) – Enough details are added into models so code can be generated

UML Structure Diagrams Represent the data and static relationships in an information system – Class – Object – Package – Deployment – Component – Composite structure

UML Behavior Diagrams Depict the dynamic relationships among the instances or objects that represent the business information system – Activity – Sequence – Communication – Interaction overview – Timing – Behavior state machine – Protocol state machine, – Use-case diagrams

Architecture Structure Decomposed into parts Interactions of parts 4+1 view

Summary What is SDLC? Explain the various phases. What are various development methodologies commonly used to develop information systems? What is the difference between UML and UP? What are various skills that are important for those involved in software development?