Waterfall Model § Key idea: Separate and distinct phases of specification and development. A phase has to be complete before moving onto the next phase. § Type: Linear model. § Recommended for: Embedded systems and Large systems(developed by several partner companies) § Disadvantage: difficulty of accommodating change after the process is underway.
V-Model § Key idea: It is an extension of Waterfall where instead of moving down in a linear way, the process steps are bent upwards after the coding phase. While tests are just one of five steps in Waterfall, it looks like practically half of the process in V-model. § Type: Linear model. § Recommended for: well-suited for projects that must maintain a strict deadline and meet key milestone dates throughout the process. Example: medical device industry § Disadvantage: same that waterfall
§ Definition: a prototype is an initial version of a system used to demonstrate concepts and try out design options. § Evolutionary model § Recommended for: a prototype can be used to help with requirements elicitation and validation; or in design processes to explore options and develop a UI design.
Spiral Model • Key idea: High amount of risk analysis hence, avoidance of Risk is enhanced. • Evolutionary model • Recommended for: (1) Good for large and mission- critical projects. (2) Strong approval and documentation control. (3) Significant changes are expected (research and exploration). • Doesn’t work well for smaller projects. • Doesn’t work well when users are unsure of their needs • Doesn’t work well when requirements are complex
Incremental Model Option A: Linear Increments (not all colors (activities) are repeated) Option B: Parallel Increments (most than 1 activity at the same time)
Manifesto • Through this work we have come to value: “Individuals and interactions over processes and tools Working software over comprehensive documentation Customer collaboration over contract negotiation Responding to change over following a plan “ • That is, while there is value in the items on the right, we value the items on the left more.
• Product development where a software company is developing a small or medium-sized product for sale. • Several software products and apps nowadays are small or medium-sized; therefore, they are developed using an agile approach • Custom system development within an organization, where there is a clear commitment from the customer to become involved in the development process and where there are few external rules and regulations that affect the software.
• The product is broken down into a set of manageable and understandable chunks. • Unstable requirements do not hold up progress. • The whole team have visibility of everything and consequently team communication is improved. • Customers see on-time delivery of increments and gain feedback on how the product works.
• The informality of agile development is incompatible with the legal approach to contract definition (requirement specification) that is commonly used in large companies. • Agile methods are most appropriate for new software development rather than software maintenance (documentation). Yet the majority of software costs in large companies come from maintaining their existing software systems. • Agile methods are designed for small co-located teams yet much software development now involves worldwide distributed teams.