1. F29IF2: Databases & Information Systems Lachlan M. MacKinnon The Information Systems Life Cycle Databases & Information Systems Lachlan M. MacKinnon

2. F29IF2: Databases & Information Systems Lachlan M. MacKinnon Why another lifecycle? äWe have seen various types of software lifecycle äThese concentrate on design and implementation of a software system äNow we are considering the whole information system äSoftware is usually involved But not always!

3. F29IF2: Databases & Information Systems Lachlan M. MacKinnon

4. The system context u These models lack an overall picture of the organisation and its business processes u A traditional structured design method extended in this manner is shown next (Based on Avison and Shah) u The similarities are clear u So are the new features

5. F29IF2: Databases & Information Systems Lachlan M. MacKinnon Information Systems lifecycle After Avison and Shah p71 IS planning Feasibility study Systems investigation Systems analysis Systems design Implementation Review and maintenance Managerial directive New business opportunities Problems with existing system Feasibility study report Project plans User requirements Staff assignment Resource requirements Methods and tools Current system data flow New system data flow Programs Evaluation report System requirements System specification Training and test plans ProceduresDocumentation New problem statement? New system in operation

6. F29IF2: Databases & Information Systems Lachlan M. MacKinnon What’s similar? u Stages rather like waterfall u Repeats with review like spiral u Progress in terms of artefacts

7. F29IF2: Databases & Information Systems Lachlan M. MacKinnon What’s added? u Feasibility study u Review during maintenance u System is an open one u Operation feeds back to design

8. F29IF2: Databases & Information Systems Lachlan M. MacKinnon Feasibility study u Propose and evaluate alternatives u Establish priorities u Gather information u Perform cost-benefit analysis u Form options for computerisation u Present conclusions The negative option is a valid option!

9. F29IF2: Databases & Information Systems Lachlan M. MacKinnon Review during maintenance u Learning from experience u Effectiveness of the solution äCorrectness of function äEfficiency äSuitability for the business process u Effectiveness of the process äKept to time? äKept to budget? äLessons learned for future developments

10. F29IF2: Databases & Information Systems Lachlan M. MacKinnon System is an open one u Take account of influences from the organisation which change over time äManagerial directives often arbitrary but often dominate decision making äNew opportunities business process change requires system change äLonger term information systems planning system change to maintain business process

11. F29IF2: Databases & Information Systems Lachlan M. MacKinnon Operation feeds back to design äOperation reveals errors - “maintenance” in SE äOperation reveals bottlenecks for the business äOperation reveals new opportunities for business äOperation reveals difficulties for users

12. F29IF2: Databases & Information Systems Lachlan M. MacKinnon Methodologies and models äA methodology (more properly a method!) is a collection of tools and techniques which help to make IS development more systematic äTypically a methodology defines a process by which an IS system can be built äTypically a process is defined by the artefacts required to be produced - models, documents, plans etc. äThe same models etc maybe used in different methodologies

13. F29IF2: Databases & Information Systems Lachlan M. MacKinnon Managing the process äManagement requires an estimate of the resources required for the project a plan for carrying out the project a set of milestones and deliverable to assess the plan äThe estimation stage is the most difficult äA variety of software metrics have been developed to assist in estimation for projects (Rick Dewar will cover these later)

14. F29IF2: Databases & Information Systems Lachlan M. MacKinnon IS planning Feasibility study Systems investigation Systems analysis Systems design Implementation Review and maintenance New business opportunities Problems with existing system The role of people in IS development Managerial directive Management scope objectives budget Users information needs operation of current system Analysts investigation analysis requirements Programmers program design testing system implementation Users test system initialise system input data use information Operators and technicians ensure smooth running fix faults

15. F29IF2: Databases & Information Systems Lachlan M. MacKinnon Improving the process äAs well as models to support the development process, there is a growing interest in models to support the improvement of the process äThe Capability Maturity Model (CMM) is a widely used model of how well controlled an organisation’s processes are äCMM defines five levels of maturity in an organisation’s processes and provides a guide to improvement

16. F29IF2: Databases & Information Systems Lachlan M. MacKinnon Reading u Avison and Shah Chapter 3 u Key Practices of the Capability Maturity Model, Vsn 1.1 Mark C. Paulk, Charles V. Weber, Suzanne M. Garcia, Mary Beth Chrissis, Marilyn Bush, Software Engineering Institute, Carnegie Mellon University, CMU/SEI-93-TR-25 ESC-TR-93-178, http://www.envisage-inc.com/OnlineLib/SEIdocs/tr25.html