Its dangers are:
??? It is less easy to allocate phases to groups and responsibilities than other models.
??? It requires that staff are well-versed in software engineering.
??? It requires much team self-discipline in the capture of emerging requirements.
??? It does not acknowledge the need to have test input from the start of the project.
??? It allocates particular phases to requirements definition and high- and low-level design.
??? It doesn??™t make the baselines explicit.
FIGURE 4.3
Boehm??™s spiral life-cycle model
Operational
Prototype
Evaluate alternatives:
identify and resolve risks
Progress through steps
Develop and
verify next-level
process plans
Evaluate
process
alternatives,
identify and
resolve process risks
Determine
process
objectives,
alternatives and
constraints
Installation
Integration
and test
Acceptance
test
Unit
test
Code
Detailed
design
Models Simulations
Software
product
design
Software
requirements
Concept of
operation
Software
requirements
validation
Prototype 1
Prototype 2
Prototype 3
Design
verification
and validation
Development
plan
Reqts.
plan life-
cycle plan
Benchmarks
Review Commitment
partition
Risk analysis
Risk analysis
Risk analysis
Cumulative cost
Determine objectives,
alternatives and
constraints
Test Planning and Management
47
??? It doesn??™t allow for process decomposition.
??? Much prototype code may eventually be used in the final version.
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