System Analysis and Design Lecture 4

System Analysis and Design

• A presentation on System Analysis and Design was given by Dr. Marwa Hussien Mohamed.
• The presentation was part of the Information Systems department, Faculty of Computer Science and Information Systems.

Lecture 4: Systems Development Methodologies

• Learning Objectives include describing various approaches to the System Development Life Cycle (SDLC) and explaining how to select a project methodology based on project characteristics.
• Systems development methodology is a formalized approach to implementing the SDLC. It's essentially a list of steps and deliverables.
• Many different methodologies exist, each varying in how progression through SDLC phases occurs.

Waterfall Development

• In waterfall development, analysts and users move sequentially from one phase to the next.
• Each phase is completed before the next begins.
• The approach is linear in structure.
• Advantages: Requirements are identified early and changes are limited. A structure is established.
• Disadvantages: Design must be complete before programming. A long time may elapse between proposal and system delivery. If requirements are incorrect, rework is costly.

Parallel Development

• Evolved to address the lengthy time frame of waterfall development.
• Projects are divided into subprojects that are designed and implemented in parallel.
• Subprojects are integrated after completion.
• Advantages: More efficient in reducing time to deliver a system, thus reducing rework due to changes in business.
• Disadvantages: Large volume deliverables. Difficult to integrate if subprojects are not completely independent.

Rapid Application Development (RAD)

• A collection of methodologies to improve on weaknesses of waterfall development.
• Incorporates special techniques and computer tools to speed up phases of analysis, design, and implementation.
• Goal is rapid development to user for evaluation.
• Advantages: System is developed faster and quality may be improved.
• Disadvantages: Can introduce problem in managing user expectations since users gain more understanding. This can accelerate changes to user expectations.

Iterative Development

• Projects are broken into series of versions.
• Fundamental requirements are in first version.
• First version is quickly developed (mini-waterfall), then users provide feedback for the next version.
• Advantages: Quickly delivers a preliminary system version to users. Additional needs can be incorporated into successive versions.
• Disadvantages: Users start with an incomplete system. Users need to be patient in the repeated introduction of new versions of the system.

System Prototyping

• Analysis, design, and implementation phases happen concurrently.
• Develops an initial, simplified system version (prototype).
• Initial prototype is often "quick and dirty" with minimal features.
• Feedback is used to improve subsequent prototypes.
• Refinement occurs until agreed-upon functionality is reached.
• Advantages: Useful when users have trouble expressing requirements, thus enabling exploration.
• Disadvantages: Potential lack of careful, methodical analysis prior to decision making. Limitations may result from inadequate understanding early in the project.

Throwaway Prototyping

• Several design prototypes are built during analysis and design phases.
• Prototypes are used to assess and validate potential issues in the system requirements.
• The prototypes are discarded after they have served their purpose.
• This distinguishes this method from system prototyping where prototypes evolve into the final product.
• Advantages: Ensures benefits of comprehensive analysis and design. Builds on advantages of prototypes in identifying issues. Produces a stable system.
• Disadvantages: Can take longer to produce final system compared to system prototyping.

Agile Development

• Streamlines SDLC, reducing modeling and documentation.
• Face-to-face communication is prioritized.
• Simple, iterative development approach. Every iteration is a complete software project.
• Iterations are short time-frames (one to four weeks).
• Emphasizing adapting to current business environment.

Extreme Programming (XP)

• Customer satisfaction, teamwork, communication, simplicity, and feedback are emphasized.
• Developers interact with customers. Designs are kept simple.
• Testing occurs early and frequently.
• Iterative development using user stories to describe system's needs. Modular code and testing to ensure fulfillment of needs.
• Quicker delivery than RAD approaches. Well-suited for smaller projects with motivated team and reliable business needs. Otherwise project success likelihood may be reduced.

Scrum

• Agile framework for complex projects.
• Iterative development.
• Emphasizes collaboration.
• Frequent communication ("Sprints").
• Specific phases include: Sprint Planning, Daily Scrum, Sprint Review, and Sprint Retrospective

Agile Principles

• Customer Satisfaction, Welcome Change, Deliver Frequently, Working Together, Motivated Team, Face-to-Face, Working Software, Constant Pace, Good design, Simplicity, Self-Organisation, Reflect and Adjust

How to Select a Development Methodology

• A table summarizes the usefulness of different methodologies in various conditions.. Provides a comparative table of usefulness in different systems development conditions. Includes considerations like unclear user requirements, unfamiliar technology, and complexity.