its inputs, outputs and actions. Following we show the detailed
comparison of each phase of the models.
Comparison Between Objectives Phase
Differences in the inter-component dependency: Comparing the
inputs of Software_Project_Objectives of the Waterfall Model and
Establish_Objectives of the Spiral Model we verified that an input
does not exist in the Waterfall Model. That shows that the model
does not have a specific phase that treats the customer's needs.
Therefore, it suggests that the inputs for the event to
Software_Project_Objectives are collected spontaneously.
Figure 8: MSDL of the Spiral Model Level 1
Differences in the need for human involvement: As in the
system objectives phase human involvement is essential for their
definition, there is no way to differentiating the human
involvement in this phase.
Differences in the development procedure: The order in both
models are quite similar, actually when they refer to the
development model many stages do not exist before the phase of
definition of objectives. However, the Spiral Model stands out as
having some additional components that differentiate it in the
quality of the stage: Risks associated to Cost and Alternative
Solutions. These components are important and fundamental in
the definition of objectives and they should be pointed out.
Table 3: Classification of the Components using MSDL
344
Differences in scope of issues: Figure 4 shows that the stage of
project objectives provides information for the establishment of
requirements. The same happens in the Figure 5 in the Spiral
Model. However it is realized that the project objectives
contributes to the phase of establishing interfaces that shows the
importance of analyzing the relationship between different parts of
the system or the relationship between different systems.
Comparison between Requirements Phase
Differences in the inter-component dependency: For the
requirements phase the Waterfall Model has two types: Establish
Requirements and Requirements Gathering while the Spiral
Model has just one: Requirements Gathering. The Waterfall
Model presents a specific type to establish requirements before
collecting it while the Spiral omits the information, it could be
interpreted that the establishment of requirements depends on the
level of the analyst's knowledge. The Waterfall Model also
specifically treats the revision of requirements, while and the
Spiral does not.
Differences in the need for human involvement: both models
need the same level of human involvement in the requirements
phase.
Differences in the development procedure: In the Waterfall
Model a stage of establishment of requirements is performed
before the actual collection, which does not happen in the Spiral
Model. It also has a procedure for definition of interfaces for the
requirements gathering. Thus, the Waterfall Model presents a
definition of requirements with more procedures than the Spiral
Model.
Differences in scope of issues: Figure 2 of the Spiral Model
presented in the Section 2 shows in the third quadrant a stage for
validation of the requirements; however, it does not specify a
revision stage. In Figure 1 of the Waterfall Model there is an input
indication for the requirements phase indicating the validation and
revision of the requirements.
Comparison between Analysis Phase
Differences in the inter-component dependency: The Waterfall
Model just presents dependences of the requirements for the
analysis phase. In the other hand, the Spiral Model presents the
phase of analysis, besides the requirements gathering, in the
analysis of alternatives established through the customer's needs.
The Spiral Model shows an analysis more focused in the risk of
the project where its execution could be interrupted in case of the
non-feasibility are greater than the feasibilities. The Waterfall
Model just presents the revision of the requirements.
Differences in the need for human involvement: For both
models the human involvement is fundamental in the analysis
criteria.
Differences in the development procedure: The Spiral Model
presents the analysis based on alternative solutions and feasibility
study. The project could be cancelled depending on the appraised
risks. The Waterfall Model presents a flow of requirements
revision, addressing in a looping between the phases, until all the
requirements have been reviewed. The continuity of the project is
not approached in the model.
Differences in scope of issues: The Waterfall Model presents the
analysis phase based on requirements while in the Spiral Model
analysis based on requirements, risks and alternative solutions.
Comparison between Design Phase
Differences in the inter-component dependency: There are no
differences between dependences assuming that the inputs
Detailed Design of the Waterfall Model and Procedure Detailed of
the Spiral Model have the same necessary inputs for the
construction of the programs.
Differences in the need for human involvement: For both
models the human involvement is fundamental in the
implementation phase.
Differences in the development procedure: There are no
differences between the models in the procedure requirement.
Differences in scope of issues: Figure 5 shows that the Spiral
Model has a simulation phase and prototyping for construction of
programs. These types contribute with the evaluation of risks and
less maintenance and code improvement. Prototyping influences
directly in the construction of the programs based on the
simulations accomplished in the prototype by the customer. The
Waterfall Model does not specifically treat this technique.
Table 4: Comparable Components Waterfall and Spiral
345
Comparison between Testing Phases
Differences in the inter-component dependency: For both
models the inputs are the executable programs indicating the
similarity of the dependence at the beginning of the phase.
Differences in the need for human involvement: For both
models the human involvement is fundamental in the analysis of
the results of the execution of the programs. However the Spiral
Model demands more human involvement since the testing phase
is separated in several interactions.
Differences in the development procedure: The Waterfall Model
has just one task for execution of tests in spite of [9] suggesting
that specialists execute the tests and that all the logics of the
program are tested. In the other hand, the Spiral Model presents a
considerable exploration of the testing phase, being incrementally
conducted in the software for each new interaction.
Differences in scope of issues: Figure 5 shows the detail of the
Spiral Model phases and Figure 2 displays in the third quadrant
the validation through the unit tests, integration and acceptance for
implementation and end of the spiral.
Comparison between Maintenance Phases
Differences in the inter-component dependency: At end of spiral
cycle there is the validation and the customer's evaluation for the
next stage. In this case the Spiral Model presents the dependence
of the customer's evaluation before maintenance what is not
clearly exposed in the Waterfall Model.
Differences in the need for human involvement: The Spiral
Model presents the customer's involvement in the maintenance
phase. That involvement identifies the need for new
improvements or the existence of mistakes.
Table 5: Summarizing the differences between Waterfall and
Spiral
Differences in the development procedure: There are no
differences between the models during maintenance.
Differences in scope of issues: In the Waterfall Model the
maintenance phase can send the development back to any phase of
the development process. In the Spiral Model the beginning of the
maintenance phase is not clearly shown, the understanding is that
the end of the quadrant develops for the next stage.
3.2.5 Summarizing of the Differences
Table 3 presents the model MSDL with the separation of the
components for process levels, and Table 4 presents the items
considered in the scope as comparable or similar. Like this after
the comparison Table 5 is presented with the summary of
differences found in the models.
In a broader sense, it can be pointed out that the Waterfall
Model is less efficient than the Spiral Model, however the exposed
differences are of comparable or similar items. Other important
items such as documentation, risk analysis and project evaluation,
for instance, were not considered comparable.
3.2.6 Integration of the Models
One of the collateral results of the comparison using CDMod is
the identification of characteristics that could be combined to form
a new improved model. Figure 9 provides a broad view of the
main characteristics of the Waterfall and Spiral that could be used
for integrating the models.
Figure 9: Kernel Slang built for the Integration Waterfall
and Spiral
4. CONCLUSIONS
CDM is a systematic and well-defined process, using a
classification of methods with modeling and science as tool of
comparison. The CDMod has a similar approach to compare
software development models, facilitating reasoning and
communication on the development model problems [12].
Differently from most of the comparisons of software
development models, the comparison using CDMod allow us to
identify the characteristics of the models as well as the qualities
346
and drawbacks of each one obeying an important logical sequence
for the comparison:
• Construction of the Process Model - Identify the
components of the models in high level, without the
concern if they will be comparable or not.
• Classification of the Components - Where through a
Structure Base Framework of the formal specification
it is possible to separate the tasks in order to allow the
identification of comparable components.
• Selection of the comparison topics - In which
comparable components are identified for the
comparison stage.
• Comparison of the Models - the comparison identifying
the qualities and drawbacks through the analysis of the
formalism.
• Summarizing of the D
its inputs, outputs and actions. Following we show the detailed
comparison of each phase of the models.
Comparison Between Objectives Phase
Differences in the inter-component dependency: Comparing the
inputs of Software_Project_Objectives of the Waterfall Model and
Establish_Objectives of the Spiral Model we verified that an input
does not exist in the Waterfall Model. That shows that the model
does not have a specific phase that treats the customer's needs.
Therefore, it suggests that the inputs for the event to
Software_Project_Objectives are collected spontaneously.
Figure 8: MSDL of the Spiral Model Level 1
Differences in the need for human involvement: As in the
system objectives phase human involvement is essential for their
definition, there is no way to differentiating the human
involvement in this phase.
Differences in the development procedure: The order in both
models are quite similar, actually when they refer to the
development model many stages do not exist before the phase of
definition of objectives. However, the Spiral Model stands out as
having some additional components that differentiate it in the
quality of the stage: Risks associated to Cost and Alternative
Solutions. These components are important and fundamental in
the definition of objectives and they should be pointed out.
Table 3: Classification of the Components using MSDL
344
Differences in scope of issues: Figure 4 shows that the stage of
project objectives provides information for the establishment of
requirements. The same happens in the Figure 5 in the Spiral
Model. However it is realized that the project objectives
contributes to the phase of establishing interfaces that shows the
importance of analyzing the relationship between different parts of
the system or the relationship between different systems.
Comparison between Requirements Phase
Differences in the inter-component dependency: For the
requirements phase the Waterfall Model has two types: Establish
Requirements and Requirements Gathering while the Spiral
Model has just one: Requirements Gathering. The Waterfall
Model presents a specific type to establish requirements before
collecting it while the Spiral omits the information, it could be
interpreted that the establishment of requirements depends on the
level of the analyst's knowledge. The Waterfall Model also
specifically treats the revision of requirements, while and the
Spiral does not.
Differences in the need for human involvement: both models
need the same level of human involvement in the requirements
phase.
Differences in the development procedure: In the Waterfall
Model a stage of establishment of requirements is performed
before the actual collection, which does not happen in the Spiral
Model. It also has a procedure for definition of interfaces for the
requirements gathering. Thus, the Waterfall Model presents a
definition of requirements with more procedures than the Spiral
Model.
Differences in scope of issues: Figure 2 of the Spiral Model
presented in the Section 2 shows in the third quadrant a stage for
validation of the requirements; however, it does not specify a
revision stage. In Figure 1 of the Waterfall Model there is an input
indication for the requirements phase indicating the validation and
revision of the requirements.
Comparison between Analysis Phase
Differences in the inter-component dependency: The Waterfall
Model just presents dependences of the requirements for the
analysis phase. In the other hand, the Spiral Model presents the
phase of analysis, besides the requirements gathering, in the
analysis of alternatives established through the customer's needs.
The Spiral Model shows an analysis more focused in the risk of
the project where its execution could be interrupted in case of the
non-feasibility are greater than the feasibilities. The Waterfall
Model just presents the revision of the requirements.
Differences in the need for human involvement: For both
models the human involvement is fundamental in the analysis
criteria.
Differences in the development procedure: The Spiral Model
presents the analysis based on alternative solutions and feasibility
study. The project could be cancelled depending on the appraised
risks. The Waterfall Model presents a flow of requirements
revision, addressing in a looping between the phases, until all the
requirements have been reviewed. The continuity of the project is
not approached in the model.
Differences in scope of issues: The Waterfall Model presents the
analysis phase based on requirements while in the Spiral Model
analysis based on requirements, risks and alternative solutions.
Comparison between Design Phase
Differences in the inter-component dependency: There are no
differences between dependences assuming that the inputs
Detailed Design of the Waterfall Model and Procedure Detailed of
the Spiral Model have the same necessary inputs for the
construction of the programs.
Differences in the need for human involvement: For both
models the human involvement is fundamental in the
implementation phase.
Differences in the development procedure: There are no
differences between the models in the procedure requirement.
Differences in scope of issues: Figure 5 shows that the Spiral
Model has a simulation phase and prototyping for construction of
programs. These types contribute with the evaluation of risks and
less maintenance and code improvement. Prototyping influences
directly in the construction of the programs based on the
simulations accomplished in the prototype by the customer. The
Waterfall Model does not specifically treat this technique.
Table 4: Comparable Components Waterfall and Spiral
345
Comparison between Testing Phases
Differences in the inter-component dependency: For both
models the inputs are the executable programs indicating the
similarity of the dependence at the beginning of the phase.
Differences in the need for human involvement: For both
models the human involvement is fundamental in the analysis of
the results of the execution of the programs. However the Spiral
Model demands more human involvement since the testing phase
is separated in several interactions.
Differences in the development procedure: The Waterfall Model
has just one task for execution of tests in spite of [9] suggesting
that specialists execute the tests and that all the logics of the
program are tested. In the other hand, the Spiral Model presents a
considerable exploration of the testing phase, being incrementally
conducted in the software for each new interaction.
Differences in scope of issues: Figure 5 shows the detail of the
Spiral Model phases and Figure 2 displays in the third quadrant
the validation through the unit tests, integration and acceptance for
implementation and end of the spiral.
Comparison between Maintenance Phases
Differences in the inter-component dependency: At end of spiral
cycle there is the validation and the customer's evaluation for the
next stage. In this case the Spiral Model presents the dependence
of the customer's evaluation before maintenance what is not
clearly exposed in the Waterfall Model.
Differences in the need for human involvement: The Spiral
Model presents the customer's involvement in the maintenance
phase. That involvement identifies the need for new
improvements or the existence of mistakes.
Table 5: Summarizing the differences between Waterfall and
Spiral
Differences in the development procedure: There are no
differences between the models during maintenance.
Differences in scope of issues: In the Waterfall Model the
maintenance phase can send the development back to any phase of
the development process. In the Spiral Model the beginning of the
maintenance phase is not clearly shown, the understanding is that
the end of the quadrant develops for the next stage.
3.2.5 Summarizing of the Differences
Table 3 presents the model MSDL with the separation of the
components for process levels, and Table 4 presents the items
considered in the scope as comparable or similar. Like this after
the comparison Table 5 is presented with the summary of
differences found in the models.
In a broader sense, it can be pointed out that the Waterfall
Model is less efficient than the Spiral Model, however the exposed
differences are of comparable or similar items. Other important
items such as documentation, risk analysis and project evaluation,
for instance, were not considered comparable.
3.2.6 Integration of the Models
One of the collateral results of the comparison using CDMod is
the identification of characteristics that could be combined to form
a new improved model. Figure 9 provides a broad view of the
main characteristics of the Waterfall and Spiral that could be used
for integrating the models.
Figure 9: Kernel Slang built for the Integration Waterfall
and Spiral
4. CONCLUSIONS
CDM is a systematic and well-defined process, using a
classification of methods with modeling and science as tool of
comparison. The CDMod has a similar approach to compare
software development models, facilitating reasoning and
communication on the development model problems [12].
Differently from most of the comparisons of software
development models, the comparison using CDMod allow us to
identify the characteristics of the models as well as the qualities
346
and drawbacks of each one obeying an important logical sequence
for the comparison:
• Construction of the Process Model - Identify the
components of the models in high level, without the
concern if they will be comparable or not.
• Classification of the Components - Where through a
Structure Base Framework of the formal specification
it is possible to separate the tasks in order to allow the
identification of comparable components.
• Selection of the comparison topics - In which
comparable components are identified for the
comparison stage.
• Comparison of the Models - the comparison identifying
the qualities and drawbacks through the analysis of the
formalism.
• Summarizing of the D
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