The Systems Analyst and Information Systems Development

The Systems Analyst and Information Systems Development

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 patients 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 Company Year Outcome Hudson Bay (Canada) 2005 Inventory system problems lead to $33.3 million loss. UK Inland Revenue

2004/ 5 $3.45 billion tax-credit overpayment caused by software errors. Avis Europe PLC (UK) 2004 Enterprise resource planning (ERP) system cancelled after $54.5 million spent. Ford Motor Co.

2004 Purchasing system abandoned after deployment costing approximately $400 M Hewlett-Packard Co. 2004 ERP system problems contribute to $160 million loss. AT&T Wireless

2004 Customer relations management system upgrade problems lead to $100M loss 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; didnt work as expected Insufficient staff Critical quality problems with software End users not sufficiently involved

(Emam et al, 2008) Systems Development Life Cycle Planning Implementatio n Analysis Design 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. 2. 3. 4. Develop a design strategy Design architecture and interfaces Develop databases and file specifications 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 Process Product Planning Project Plan Analysis

System Proposal Design Implementation System Specification New System and Maintenance Plan 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 Requirements Design Implementation Maintenance Cost of Fixing Problems 900 800 Cost to fix 700 600

500 400 300 200 100 0 Requirements Design Code Development Test

Acceptance Test Operation Software Faults 60 50 40 Errors Introduced % of all faults 30 Errors Observed 20

10 0 Requirements Design Construction Operation Selecting the Right Methodology Usefulness for Waterfall

Prototyping Throwaway Prototyping Extreme Programming Unclear user requirements Poor Excellent

Excellent Excellent Unfamiliar technology Poor Poor Excellent Poor

Complex systems Good Poor Excellent Poor Reliable systems Good Poor

Excellent Good Short time schedule Poor Excellent Good Excellent

Schedule visibility Poor Excellent Good Good Process What, when, who, and how? From requirements to software New or changed requirements

Software Engineering Process New or changed system Unified Modeling Language - A visual language Unified Process - A 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 objectoriented 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 Logical view Diagrams: Class Object Package

State Implementation view Diagrams: Component Use case View Diagrams: Use case Interaction Process view Diagrams: Class Object

Deployment view Diagrams: Deployment 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?

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