Class 15 System Life Cycle

Outline System Life Cycle (Structured & Rapid methodologies) System Planning (3 strategic goals) SLC Activities System Life CycleInformation Systems for Management2

System Life CycleInformation Systems for Management3 System Life Cycle (SLC) SLC = activities an IS goes through its inception to/phases can be run in sequence or in iteration. - Waterfall (structured) methodology: Development activities make separate phases that run in linear sequence without repetition. - Pro: Precise planning of time & resources * - Con: Long development cycle** & less responsive to business change Installation Construction Systems Planning Phase out

System Life CycleInformation Systems for Management4 4 4 Alternative: Rapid Methodologies Strengths (pros)Weaknesses (cons) Fast and more responsive to changes in business May not suit large complex systems Useful when systems requirements are uncertain or business changes fast Can miss some steps in analysis, documentation and testing Promotes user involvement in SLC Newer methodology based on faster development technologies and quickly changing business needs. Project time usually under 1 year. Development activities repeated for each part of system. Steps: Identify some of user’s requirements (e.g., a key function of the IS) Develop a function prototype, needed part of database, and access screens Test prototype & learn from users Revise & enhance prototype based on users’ opinions Test, roll out, and move to the next piece of the system

System Life CycleInformation Systems for Management5 What organizational changes can be accomplished with new system: Automation of manual tasks (e.g., MIS, DSS, Expert system, communication systems) Business Process Reengineering (BPR) - radical change of organization; process efficiency key goal* Quality improvements (Benchmarking – test of compliance with standards)** Systems Planning

System Life CycleInformation Systems for Management6 Systems Analysis Analysis of organizational needs to be met with an information system focusing on 1. data/information as part of jobs and tasks 2. data transformation (data processing aspect on an IS) 1. Data analysis: define Information Needs Identifies what data are needed by particular members of an organization (your data diagram) Collect business documents (financial papers, reports…), interview users & managers 2. Software processes transforming data Parts of a database

System Life CycleInformation Systems for Management7 Systems Design Creating IS-based solution for meeting organization’s information and management needs Design encompasses: Data (usually some database) Software processes applied to data (functionality) User Interface (screens for data input and for the output) Programming/Construction follows (can be putting together of purchased of-the-shelf software)*

System Life CycleInformation Systems for Management8 Testing Testing – assessing quality of the developed system Kinds of tests applied that from smaller parts to a large system: Unit testing (test each system function separately) Cross-unit testing (test functions that depend on each other) System testing (tests IS as a whole; e.g., overload the system to see how robust it is)

System Life CycleInformation Systems for Management9 Installation Methods Direct cutover New system completely replaces old one at a certain date Parallel installation Old and new system used in parallel, until the new system proves reliable Phased installation New system introduced part by part and the old system phased out gradually (a new system turned on function by function or entirely in one part of a firm) time Old ISNew IS time Old IS New IS time Old IS New IS Function New IS Function Old Functions phased out

System Life CycleInformation Systems for Management10 Production Stage and Maintenance System is being used for organizational needs Operate the system Evaluate the system Maintain the system (modify it as needed – work out software bugs, improve user interface, increase secondary storage)