Software Development Life Cycle
Software Development Life Cycle
Software Development Life Cycle
Prototyping
Construction phase
Cutover phase
RAD Strengths
Reduced cycle time and improved productivity
with fewer people means lower costs
Customer involved throughout the complete cycle
minimizes risk of not achieving customer
satisfaction and business needs
Focus moves from documentation to code
Uses modeling concepts to capture information
about business, data, and processes.
RAD Weaknesses
Accelerated development process must give quick
responses to the user
Risk of never achieving closure
Hard to use with legacy systems
Requires a system that can be modularized
Developers and customers must be committed to
rapid-fire activities in an abbreviated time frame.
May compromises functionality and performance
in exchange for faster development and better
application maintenance
When to use RAD
When requirements are not fully understood.
User involved throughout the life cycle
Functionality delivered in increments
High performance not required
System can be modularized
Incremental SDLC Model
Construct a partial
implementation of a total
system
Then slowly add increased
functionality
The incremental model
prioritizes requirements of the
system and then implements
them in groups.
Each subsequent release of the
system adds functions to the
previous release, until all
designed functionality has been
implemented.
Incremental Model Strengths
Develop high-risk or major functions first
Each release delivers an operational product
Customer can respond to each build
Uses “divide and conquer” breakdown of tasks
Lowers initial delivery cost
Initial product delivery is faster
Customers get important functionality early
Incremental Model Weaknesses
Requires good planning and design
Requires early definition of a complete and fully
functional system to allow for the definition of
increments
Well-defined module interfaces are required (some
will be developed long before others)
Total cost of the complete system is not lower
When to use the Incremental Model
Most of the requirements are known up-front but
are expected to evolve over time
A need to get basic functionality to the market
early
On projects which have lengthy development
schedules
Spiral SDLC Model
Adds risk analysis, and
4gl RAD prototyping to
the waterfall model
Each cycle involves the
same sequence of steps
as the waterfall process
model
Spiral Quadrant
Determine objectives, alternatives and constraints