SFDV Principles of Information Systems Lecture 2 Building Information Systems

2 Overview  What is systems development?  Why do we need it?  How can we develop systems successfully?  Systems Development Life Cycle (SDLC)  Approaches to SDLC  Who is involved in systems development?  A special CASE

3 Systems Development Projects  “…the activity of creating or modifying existing business systems. It refers to all aspects of the process—from identifying problems to be solved or opportunities to be exploited to the implementation and refinement of the chosen solution.”  Project: “A planned undertaking that has a beginning and an end, and that produces a desired result or product.”  Attempts to achieve the following three main goals Deliver on budget on time meets the client’s requirements (i.e. what they want) [source: Stair and Reynolds, 2003] [source: Satzinger et al., 2004]

4  Cost overruns  Software quality problems  Missed deadlines  Unsatisfied stakeholders  Operational failure  No system delivered What constitutes top of project failure?  Unreliable (characteristics of successful systems).  No system delivered at all for whatever reason. Hard-pressed to get a job if that happened. What Counts as Project Failure?

5 A Note on Successful Systems Efficiency Usability CorrectnessPerformance Robustness Dependability Reliability Maintainability User Friendliness Evolvability

6 Maintainability: It should be possible for the software to evolve to meet changing requirements. Dependability: The software should not cause physical or economic damage in the event of failure. Efficiency: The software should not make wasteful use of system resources. Usability: Software should have an appropriate user interface and documentation. So that the people can actually use it. Correctness: A program is functionally correct if it behaves according to the specification of the functions. Reliability: Software is reliable if the user can depend on it or the software will operate as expected over a specified time interval (MTTF). Robustness: A program is robust if it behaves "reasonably," even in circumstances that were not anticipated in the requirements specification. Performance: A software system is efficient if it uses computing resources economically. User Friendliness: A software system is user friendly if its human users find it easy to use. Subjective interpretations. One test is - can a novice user use it? Evolvability: Software products are modified over time to provide new functions or to change existing functions.

7 Systems Development Life Cycle (SDLC)  “A project management framework organized into phases and activities”  General prescription for developing systems  Comprises a collection of interlinked phases  Variations include »  System Initiation  Investigation  Feasibility Study  Programming  Construction  Deployment  Maintenance  Review [source: Satzinger et al., 2004]

8  Project Planning  Objectives »  Identify the scope of the new system  Plan the project  Assess feasibility and prepare budget  Main activities » 1. Define the problem 2. Produce the project schedule 3. Confirm project feasibility 4. Staff the project 5. Launch the project [source: Satzinger et al., 2004]

9  Objectives »  Understand user needs  Develop requirements  Learn as much as possible about problem domain  Main activities » 1. Gather information 2. Define system requirements 3. Build prototypes 4. Prioritise requirements  Analysis 5. Generate and evaluate alternatives 6. Review recommendations with management Outputs of analysis: Strengths and weaknesses of the existing system, the user/ stakeholder requirements for the new system, the organisational requirements for the new system, A description of what the new information system should do.

10  Design  Objective »  Design solution system  Answers ‘how to do it?’ rather than ‘what to do?’  Main activities » 1. Design database 2. Design application 3. Design user interfaces 4. Design system interfaces 5. Create/evolve prototype 6. Design system controls

11  Implementation  Objectives »  Build solution system  Test solution  Main activities » 1. Construct software components 2. Verify and test 3. Convert data 4. Train users and document the system 5. Install the system  Also, acquire hardware and software  Install solution

12  Support  Objective »  Keep system running productively after installation  Main activities » 1. Maintain the system 2. Enhance the system 3. Support the users  Reasons for initiating this phase include »  Changes in business processes  New requests from stakeholders, users, and managers  Bugs or errors in the program  Technical and hardware problems  Unexpected events

13  Purpose:  Checking, changing, and enhancing the system to make it more useful in obtaining user and organizational goals.  Can consume large amounts of resources  Resource = developer time mostly.  Related to ‘software evolution’.  Environmental effects: change in law, improvements in the way they do things, more customers, expansion and so on.  New requests can be activated by some of the other items (e.g., Gov. regulations, mergers).

14 Participants in Systems Development  Projects comprise teams of people each with different roles  Examples of stakeholders »  Users  Managers  Systems development specialists  Project managers  Support personnel  External

 People are vitally important. Development approaches in recent times try to include clients, users and so on wherever possible.  Analogy (architecture): Architect (+ team), Client (wanting house), Builders, Plumber, Electrician, Council representative (building consent, codes of compliance), Project manager  Stakeholders: Individuals that benefit or are affected in some way by the results of a SD project Example: Clients  pay for project  Users: interact with the system regularly  Managers: Management, in charge of functional area like Accounts, Sales. Paying for development 15

 Systems development specialists: system analysts, programmers, requirements engineers, testers, documents, database designers, etc. you.  Project managers: coordinate development process, run project, organise development specialists)  next weeks lecture discusses project management.  Support personnel: technical support, run the system when it is implemented  External: Shareholders, councils, standards bodies, etc. 16

17  CASE »  Sybase PowerDesigner Rational Rose  Oracle Designer  Tools for »  Testing  Configuration management  Documentation support  Project management  … Systems Development Tools  Application development »  Microsoft Access  Oracle Developer  IBM Websphere  IDEs »  Microsoft Visual Studio.NET for VB, C++  Eclipse for JAVA Provides categories of different software tools used in the development process.

18 Computer Aided Software Engineering  “Automate many of the tasks required in a systems development effort and enforce adherence to the SDLC, thus instilling a high degree of rigor and standardization to the entire systems development process.”  “Software programs that automate or support the drawing and analysis of system models and provide for translation of system models into application programs.” [source: Stair and Reynolds, 2003] [source: Whitten et al., 2004]

 Collection of programs.  Support or automate design, analysis, translation (transformation).  Support engineering-type discipline through: Common techniques Standard methodologies Automated tools  Facilitate design and construction of system specifications  Generate forms, reports, and code  Typically based around a particular design paradigm 19 Computer Aided Software Engineering

20 Summary  Building information systems is a complex undertaking in which success is not guaranteed  Development projects attempt to finish on budget, on time and to satisfy the requirements of the client  Numerous stakeholders (directly or indirectly) participate in a project  The SDLC provides a generic framework for structuring project activities  The quality and time of the analysis, design and implementation activities can be improved by CASE   NOTE: ALL STUDENTS MUST START Practical Sessions 1