Systems lifecycle methodologies Flashcards
What are the phases of waterfall model?
Requirement gathering and analysis System design Implementation Integration and Testing Deployment of system Maintenance
What are situations where waterfall is appropriate?
Requirements are well documented, clear and fixed
Product definition is stable
Technology is understood and not dynamic
No ambiguous requirements
Short project
Ample resources with required expertise available to support the product.
In waterfall, no stage of development can be begun until what?
Preceding stage has been completed.
Waterfall advantages
Simple and easy to understand and use Easy to manage due to rigidity. Phases are processed and completed one at a time Works well for smaller projects where requirements well understood Clearly defined stages Well understood milestones Easy to arrange tasks Process and results well documented.
Waterfall disadvantages
No working software produced until late during life cycle
High risk and uncertainty
Not good model for complex and object oriented projects
Poor for long and ongoing projects
Not suitable for requirements that are likely to change
Difficult to measure progress within stages.
Cant accommodate changing requirements.
How does spiral model work?
Reduced number of stages are visited and revisited in a constant quest for perfection. This approach is iterative and each completed cycle is referred to as an iteration of the development.
What is the identification phase of spiral model?
Gathering business requirements in baseline spiral.
In subsequent spirals as product matures, identification of requirements are done.
Also includes understanding system requirements by customer and system analyst communicating. Product deployed at end of spiral.
What is the design phase of the spiral model?
Starts with conceptual design in baseline spiral and involves architectural design, logical design of modules, physical product design and final design in the subsequent spirals.
What is the construct/build phase of the spiral model?
Production of actual software product at every spiral.
In baseline spiral, Proof of Concept (POC) developed to get customer feedback. In subsequent spirals with higher clarity on requirements and design details, a working model called build is produced with version number, sent to customer for feedback.
What is the evaluation/risk analysis of the spiral model?
Identifying estimating and monitoring technical feasibility and management risks, such as schedule slippage and cost overrun. After testing first build, at end of first iteration, customer evaluates software and provides feedback.
