Chapter 1: Introduction to Systems Development Flashcards
System Analysis and Design
• Step by step process
- Developing high quality information systems
System Analyst
• To plan, develop, and maintain Information systems
How to acquire Information Systems
• Bespoke system - Created specially for the customer • Off-the-shelf - Bought ‘as is’ - Example: ~ Microsoft Windows 10 • Customized off-the-shelf - Core system is customized ~ Meet the needs of a particular customer - Modifying the standard system
What is an information system
• System - Set of related components ~ Produces specific results • Mission-critical system - Vital to a company’s operations - Example: ~ Order processing system ~ Inventory system • Data - Consists of basic facts ~ System’s raw material
Information System Components (*)
Five key components: • Hardware • Software • Process • Data • People
Information
Data the has been transformed into output that is valuable to users.
Hardware
Physical layer
• Example:
- Moore’s Law:
~ Number of transistor double about every 24 months in an integrated circuit chip
Software
• Programs that control the hardware - Produces the desired information or results • System software: - Manages hardware components - Example: ~ Operating system ~ Device drivers • Application software: - Support day-to-day functions • Enterprise applications: - Used for the whole company - Example: ~ Order processing system • Vertical systems: - Designed to meet the unique requirements of a specific business or industry
Data
• Raw material - Transforms into useful information • Tables store data • Linking tables - System can extract specific information
Processes
• Describes:
- Tasks
- Business functions
• Perform to achieve specific results
People
- Stakeholders
* Users/End Users
Business process modelling
Involves:
• Business profile
• A set of models
- Document business operations
Business profile
Overview of a company's: • Mission • Functions • Customers • Products • Etc.
Business Process
• Specific set of: - Transactions - Events - Results • Can be described & documented
Types of business
• Brick-and-mortar - Shops that sells product without an online presence • Production-oriented - Sells high quality products - Ignores customer’s needs • Service-oriented - Provides intangible products - Example: ~ Banking ~ Education ~ Treatment
New kinds of companies
• Internet-dependent
- Sells products online
• Dot-com(.com)
Users and Needs
• Top managers - Strategic plans – long range plans (long-term goals) ~ Defines company’s overall missions & goals • Middle Managers and Knowledge Workers - Provides: ~ Direction ~ Necessary resources ~ Performance feedback • Supervisors and Team Leaders - Carry out: ~ Day-to-day functions • Operational Employees: - Empowerment ~ More responsibility and accountability
Organizational Structure of an Enterprise
• Strategic: - Senior Managers ~ Long-range planning ~ Strategic decisions • Managerial: - Middle Managers ~ Implement goals ~ Make tactical decisions ~ Plan & control operations • Operational: - Operational Managers (First Line Managers) ~ Manages general workforce ~ Monitor day-to-day events ~ Make operational decisions
Overview of Systems Development Methods (*)
Modeling • Produces a graphical representation of a concept or process that systems developer can: - Analyze - Test - Modify
Structured Analysis
• Predictive approach - Focuses on: ~ Structure - Maintaining: ~ Holistic vision of the solution space • Uses a set of process models - To describe a system graphically • Process-centered technique • Waterfall model • Systems development life cycle
Systems Development Life Cycle (SDLC) (*)
Describes activities and functions that all systems developers perform (5 phases):
• Systems planning
- Preliminary investigation report (deliverable)
• Systems analysis
- System requirements document (deliverable)
• Systems design
- System design specification (deliverable)
• Systems implementation
- Functioning system (deliverable)
• Systems security and support
- Fully operational system (deliverable)
Systems planning (time, budget, etc)
• Systems request - Begins the process - Describes problems or desired changes • Purpose: - Perform a preliminary investigation ~ Key part – Feasibility study • Deliverable: - Preliminary investigation report
Systems analysis (What, how, who, when)
First step: • Requirements modeling - Investigate business processes - Document what the new systems must do to satisfy users • Deliverable: - System requirements document
Systems design (plan, what to look like)
• Logical design (analysis) into physical design • Identify: - Output - Input - Processes • Design: - Internal controls - External controls • Determine: - Application architecture • Critical/Important: - Management - User involvement • Deliverable: - System design specification
Systems implementation
• New systems is constructed (theory becomes practice) • Programs: - Written ~ Implementation of the design specified in the design document - Tested ~ Detection of errors - Documented • System is installed • Assessment: - System evaluation ~ Process of assessing the performance of a complete system in live market conditions • Deliverable: - Functioning system
Systems support and security (maintenance)
• Well-designed system must be: - Secure } - Reliable } - Deliverables - Maintainable } - Scalable } • Most information systems: - Updated significantly - Replaced after several years of operation ~ Update or replace • 3 main concerns: - Security requirements - User expectations - System performance • Deliverable: - Fully operational system
Disadvantages of Structural Analysis
• The waterfall model does not emphasize interactivity among phases
- This criticism can be valid if the SDLC phases are followed too rigidly.
Object-oriented analysis
• Objects: - Combined data & processes that act on the data - Member of a class - Possesses properties • Methods: - Change an object’s properties • Message: - Requests specific behavior/information ~ From another object - Similar to the SDLC • Interactive model • Advantages: - Focuses on data rather than procedures
Agile/adaptive Methods
• Newest development / Latest method • Emphasizes continuous feedback (interaction/communication) • Iterative development • Published Agile Manifesto: - Individuals & interaction - Working software - Responding to change • Spiral model • Determines end result • Examples: - Scrum - Extreme Programming (XP)
Joint Application Development (JAD)
• Team-based fact finding (analysis)
- Only one phase of the development process
• Deliverables:
- System requirement documents
Rapid Application Development (RAD)
• Compressed version of the entire process
• Deliverables:
- New information system
