The information systems lifecycle Far more boring than you ever dreamed possible!

What prompts a new system? The current system may no longer be suitable for its purpose The current system may no longer be suitable for its purpose Technological developments may have made the current system redundant or outdated Technological developments may have made the current system redundant or outdated The current system may be too inflexible or expensive to maintain The current system may be too inflexible or expensive to maintain

The lifecycle model Investigation Implementation

Systems development life cycle (the ‘Waterfall model’)

System Investigation Interviewing staff at different levels Interviewing staff at different levels –from end-users to senior management Examining current business and systems documents and output (records) Examining current business and systems documents and output (records) –may include current order documents, computer systems procedures and reports used by operations and senior management Sending out questionnaires Sending out questionnaires Observation of current procedures Observation of current procedures –by spending time in various departments; a time and motion study can show where procedures could be more efficient, or to detect bottlenecks

Feasibility study Fact Find Fact Find Technical feasibility Technical feasibility Economic feasibility Economic feasibility Legal feasibility Legal feasibility Operational feasibility Operational feasibility –are the current work practices and procedures adequate to support the new system? Schedule feasibility Schedule feasibility –how long will the system take to develop, or can it be done in a desired time-frame? Costs & benefits of the new system Costs & benefits of the new system Draft Plan for implementation Draft Plan for implementation

System Analysis Understanding: Understanding: –The existing system –Understanding the proposed system –Gathering user requirements –Setting out the solution using tools; Data Models System analysis Data Models System analysis DFD DFD ER diagrams ER diagrams Decision tables Decision tables –Producing the specification

System design The hardware platform The hardware platform –which type of computer, network capabilities, input, storage and output devices The software The software –programming language, package or database The outputs The outputs –report layouts and screen designs The inputs The inputs –documents, screen layouts, validation procedures, data dictionary The user interface The user interface –how users will interact with the computer system The modular design The modular design –of each program in the application The test plan and test data The test plan and test data Conversion plan Conversion plan –how the new system is to be implemented Documentation Documentation –User –Technical

Implementation Coding and testing of the system Coding and testing of the system Acquisition of hardware and software Acquisition of hardware and software Installation of the new system Installation of the new system Installing the new hardware, which may involve extensive recabling and changes in office layouts; Installing the new hardware, which may involve extensive recabling and changes in office layouts; Training the users on the new system; Training the users on the new system; Conversion of master files to the new system, or creation of new master files. Conversion of master files to the new system, or creation of new master files.

Methods of conversion/changeover Direct changeover Direct changeover –The user stops using the old system one day and starts using the new system the next Parallel changeover Parallel changeover –The old system continues alongside the new system for a few weeks or months Phased conversion Phased conversion –Used with larger systems that can be broken down into individual modules that can be implemented separately at different times Pilot conversion Pilot conversion –New system will first be used by only a portion of the organisation, for example at one branch or factory

System maintenance Perfective maintenance Perfective maintenance –implies that while the system runs satisfactorily, there is still room for improvement Adaptive maintenance Adaptive maintenance –All systems will need to adapt to changing needs within a company Corrective maintenance Corrective maintenance –Problems frequently surface after a system has been in use for a short time, however thoroughly it was tested

Technical & user documentation User Documentation User Documentation –Minimum hardware, load software, save, print, certain functions, FAQ, deal with errors and backup data Technical Documentation Technical Documentation –System design specification, diagrams to represent the system, data dictionary, design of processes, screen layout design, user interface design and test plan.

Tools for gathering information for evaluation Quantitative Test Quantitative Test –Numerical data allows performance to evaluated and compared. Error log interviews Error log interviews –Calls top help desk logged –Interviews with the managers Questionnaire Questionnaire –User based feedback (usually anonymous)

Avoid Post implementation costs Training costs Training costs Modification costs Modification costs Help-desk and support costs Help-desk and support costs Costs of additional hardware Costs of additional hardware Correction of bugs Correction of bugs