Prototype Testing:
Developers build a prototype during the requirements phase
Prototype is evaluated by end users
Users give corrective feedback
Developers further refine the prototype
When the user is satisfied, the prototype code is brought up to the standards needed for a final Product.
Prototype Steps:
A preliminary project plan is developed
An partial high-level paper model is created
The model is source for a partial requirements specification
A prototype is built with basic and critical attributes
The designer builds the database,User Interface,algorithmic functions
The designer demonstrates the prototype, the user evaluates for problems and suggests improvements.
This loop continues until the user is satisfied
Prototyping Weaknesses:
Tendency to abandon structured program development for “code-and-fix” development
Bad reputation for “quick-and-dirty” methods
Overall maintainability may be overlooked
The customer may want the prototype delivered.
Process may continue forever (scope creep)
When to use Prototype Model:
Requirements are unstable or have to be clarified
As the requirements clarification stage of a Waterfall model
Develop user interfaces
Short-lived demonstrations
New, original development
With the analysis and design portions of object- oriented development.
Tuesday 5 June 2012
Spiral Model:
Spiral Model:
The spiral model is a realistic approach to the development of large-scale software products because the software evolves as the process progresses. In addition, the developer and the client better understand and react to risks at each evolutionary level.
The model uses prototyping as a risk reduction mechanism and allows for the development of prototypes at any stage of the evolutionary development.
It maintains a systematic stepwise approach, like the classic Life Cycle model, but incorporates it into an iterative framework that more reflect the real world.
If employed correctly, this model should reduce risks before they become problematic, as consideration of technical risks are considered at all stages
Spiral Model Strengths:
Provides early indication of insurmountable risks, without much cost
Users see the system early because of rapid prototyping tools
Critical high-risk functions are developed first
The design does not have to be perfect
Users can be closely tied to all life cycle steps
Early and frequent feedback from users
Cumulative costs assessed frequently
Spiral Model Weaknesses:
Time spent for evaluating risks too large for small or low-risk projects
Time spent planning, resetting objectives, doing risk analysis and prototyping may be excessive
The model is complex
Risk assessment expertise is required
Spiral may continue indefinitely
Developers must be reassigned during non-development phase activities
May be hard to define objective, verifiable milestones that indicate readiness to proceed through the next iteration
The spiral model is a realistic approach to the development of large-scale software products because the software evolves as the process progresses. In addition, the developer and the client better understand and react to risks at each evolutionary level.
The model uses prototyping as a risk reduction mechanism and allows for the development of prototypes at any stage of the evolutionary development.
It maintains a systematic stepwise approach, like the classic Life Cycle model, but incorporates it into an iterative framework that more reflect the real world.
If employed correctly, this model should reduce risks before they become problematic, as consideration of technical risks are considered at all stages
Spiral Model Strengths:
Provides early indication of insurmountable risks, without much cost
Users see the system early because of rapid prototyping tools
Critical high-risk functions are developed first
The design does not have to be perfect
Users can be closely tied to all life cycle steps
Early and frequent feedback from users
Cumulative costs assessed frequently
Spiral Model Weaknesses:
Time spent for evaluating risks too large for small or low-risk projects
Time spent planning, resetting objectives, doing risk analysis and prototyping may be excessive
The model is complex
Risk assessment expertise is required
Spiral may continue indefinitely
Developers must be reassigned during non-development phase activities
May be hard to define objective, verifiable milestones that indicate readiness to proceed through the next iteration
Monday 4 June 2012
The V-model
The V-model represents a software development
process ( also applicable to hardware development )
which may be considered an extension of the Waterfall model . Instead of moving down in a linear way ,
the process steps are bent upwards after the coding phase , to form the typical V shape . The V-Model
demonstrates the relationships between each phase of the development Life Cycle and its associated
phase of testing . The horizontal and vertical axes represents time or project completeness ( left-to-right )
and level of abstraction ( coarsest-grain abstraction uppermost ) , respectively .
The V Model , while admittedly obscure , gives equal weight to testing rather than treating it as an afterthought .Initially defined by the late Paul Rook in the late 1980s , the V was included in the U .K .’s National
Computing Center publications in the 1990s with the aim of improving the efficiency and effectiveness of
software development . It’s accepted in Europe and the U .K . as a superior alternative to the waterfall model ;
yet in the U .S . , the V Model is often mistaken for the waterfall .
V-Model : V- stands for Verification and Validation
1.It is a recognized model by organizations
2.This model defines the mapping in between multiple stages of development and multiple stages of testing
To decrease project cost ,the organizations are maintaining the separate testing team only for system testing . Because the system testing stage is working as bottle neck stage in software development .
which may be considered an extension of the Waterfall model . Instead of moving down in a linear way ,
the process steps are bent upwards after the coding phase , to form the typical V shape . The V-Model
demonstrates the relationships between each phase of the development Life Cycle and its associated
phase of testing . The horizontal and vertical axes represents time or project completeness ( left-to-right )
and level of abstraction ( coarsest-grain abstraction uppermost ) , respectively .
The V Model , while admittedly obscure , gives equal weight to testing rather than treating it as an afterthought .Initially defined by the late Paul Rook in the late 1980s , the V was included in the U .K .’s National
Computing Center publications in the 1990s with the aim of improving the efficiency and effectiveness of
software development . It’s accepted in Europe and the U .K . as a superior alternative to the waterfall model ;
yet in the U .S . , the V Model is often mistaken for the waterfall .
V-Model : V- stands for Verification and Validation
1.It is a recognized model by organizations
2.This model defines the mapping in between multiple stages of development and multiple stages of testing
To decrease project cost ,the organizations are maintaining the separate testing team only for system testing . Because the system testing stage is working as bottle neck stage in software development .
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