class 15 system life cycle. outline system life cycle (structured & rapid methodologies) system...
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Outline
System Life Cycle (Structured & Rapid methodologies)
System Planning (3 strategic goals)
SLC Activities
System Life CycleInformation Systems for
Management 2
System Life CycleInformation Systems for
Management 3
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 thatrun in linear sequence without repetition.
- Pro: Precise planning of time & resources *
- Con: Long development cycle** &less responsive to business change
Installation Cons
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Systems Planning
Phase out
System Life CycleInformation Systems for
Management 4Information Systems for
Management 4Information Systems for
Management 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
Management 5
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
Management 6
Systems AnalysisAnalysis of organizational needs to be met with an information system focusing on
1. data/information as part of jobs and tasks2. data transformation (data processing aspect on an IS)
1. Data analysis: define Information NeedsIdentifies 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
Management 7
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
Management 8
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
Management 9
Installation MethodsDirect cutover
New system completely replaces old one at a certain date
Parallel installationOld and new system used in parallel, until the new system proves reliable
Phased installationNew 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)
timeOld IS New IS
timeOld IS
New IS
time Old IS
New IS Function
New IS Function
Old Functions phased out