Cascade model software engineering
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Q1. State and explain various workflows.
The term workflow is used to mean a thread of cohesive and mostly sequential activities. Workflows are mapped to product artifacts and to project. There are seven top-level workflows:
??Management workflow: controlling the process and ensuring win conditions for all stakeholders
??Environment workflow: automating the process and evolving the maintenance environment
??Requirements workflow: analyzing the problem space and evolving the requirements artifacts
??Design workflow: modeling the solution and evolving the architecture and design artifacts
??Implementation workflow: programming the components and evolving the implementation and deployment artifacts
??Assessment workflow: assessing the trends in process and product quality
??Deployment workflow: transitioning the end products to the user
The figure given above illustrates the relative levels of effort expected across the phases in each of the top-level workflows. It represents one of the key signatures of a modern process framework and provides a viewpoint from which to discuss several of the key principles.
• Architecture-first approach
o Extensive requirements analysis, design, implementation, and assessment activities are performed before the construction phase, when full-scale implementation is .The focus. This early life-cycle focus on implementing and testing the architecture must precede full-scale development and testing of all the components and must precede the downstream focus on completeness and quality of the entire breadth of the product features.
• Iterative life-cycle process
o In the figure given above, each phase portrays at least two iterations of each workflow. This default is intended to be descriptive, not prescriptive. Some projects may require only one iteration in a phase; others may require several iterations. The point is that the activities and artifacts of any given workflow may require more than one pass to achieve adequate results.
• Round-trip engineering
o Raising the environment activities to a first-class workflow is critical. The environment is the tangible embodiment of the project’s process, methods, and notations for producing the artifacts.
• Demonstration-based approach
o Implementation and assessment activities are initiated early in the life cycle, reflecting the emphasis on constructing executable subsets of the evolving architecture.
Q2. Write a short note on iterative workflows.
Iteration consists of a loosely sequential set of activities in various proportions, depending on where the iteration is located in the development cycle. Each iteration is defined in terms of a set of allocated usage scenarios.
The components needed to implement all selected scenarios are developed and integrated with the results of previous iterations. An individual iteration’s workflow, illustrated in the figure given below, generally includes the following sequence:
1. Management: iteration planning to determine the content of the release and develop the detailed plan for the iteration; assignment of work packages, or tasks, to the development team
2. Environment: evolving the software change order database to reflect all new baselines and changes to existing baselines for all product, test, and environment components
3. Requirements: analyzing the baseline plan, the baseline architecture, and the baseline requirements set artifacts to fully elaborate the use cases to be demonstrated at the end of this iteration and their evaluation criteria; updating any requirements set artifacts to reflect changes necessitated by results of this iteration's engineering activities
4. Design: evolving the baseline architecture and the baseline design set artifacts to elaborate fully the design model and test model components necessary to demonstrate against the evaluation criteria allocated to this iteration; updating design set artifacts to reflect changes necessitated by the results of this iteration’s engineering activities
5. Implementation: developing or acquiring any new components, and enhancing or modifying any existing components, to demonstrate the evaluation criteria allocated to this iteration; integrating and testing all new and modified components with existing baselines (previous versions)
6. Assessment: evaluating the results of the iteration, including compliance with the allocated evaluation criteria and the quality of the current baselines; identifying any rework required and determining whether it should be performed before deployment of this release or allocated to the next release; assessing results to improve the basis of the subsequent iteration’s plan
7. Deployment: transitioning the release either to an external organization (such as a user, independent verification and validation contractor, or regulatory agency) or to internal closure by conducting a post-mortem so that lessons learned can be captured and reflected in the next iteration
Q3. Write a short note on joint management reviews.
The four major milestones occur at the transition points between life-cycle phases. They can be used in many different process models, including the conventional waterfall model. In an iterative model, the major milestones are used to achieve concurrence among all stakeholders on the current state of the project. Different stakeholders have very different concerns:
• Customers: schedule and budget estimates, feasibility, risk assessment, requirements understanding, progress, product line compatibility
• Users: consistency with requirements and usage scenarios, potential for accommodating growth, quality attributes
• Architects and systems engineers: product line compatibility, requirements changes, trade-off analyses, completeness and consistency, balance among risk, quality, and usability
• Developers: sufficiency of requirements detail and usage scenario descriptions, frameworks for component selection or development, resolution of development risk, product line compatibility, sufficiency of the development environment
• Maintainers: sufficiency of product and documentation artifacts, understandability, interoperability with existing systems, sufficiency of maintenance environment
• Others: possibly many other perspectives by stakeholders such as regulatory agencies, independent verification and validation contractors, venture capital investors, subcontractors, associate contractors, and sales and marketing teams
The term workflow is used to mean a thread of cohesive and mostly sequential activities. Workflows are mapped to product artifacts and to project. There are seven top-level workflows:
??Management workflow: controlling the process and ensuring win conditions for all stakeholders
??Environment workflow: automating the process and evolving the maintenance environment
??Requirements workflow: analyzing the problem space and evolving the requirements artifacts
??Design workflow: modeling the solution and evolving the architecture and design artifacts
??Implementation workflow: programming the components and evolving the implementation and deployment artifacts
??Assessment workflow: assessing the trends in process and product quality
??Deployment workflow: transitioning the end products to the user
The figure given above illustrates the relative levels of effort expected across the phases in each of the top-level workflows. It represents one of the key signatures of a modern process framework and provides a viewpoint from which to discuss several of the key principles.
• Architecture-first approach
o Extensive requirements analysis, design, implementation, and assessment activities are performed before the construction phase, when full-scale implementation is .The focus. This early life-cycle focus on implementing and testing the architecture must precede full-scale development and testing of all the components and must precede the downstream focus on completeness and quality of the entire breadth of the product features.
• Iterative life-cycle process
o In the figure given above, each phase portrays at least two iterations of each workflow. This default is intended to be descriptive, not prescriptive. Some projects may require only one iteration in a phase; others may require several iterations. The point is that the activities and artifacts of any given workflow may require more than one pass to achieve adequate results.
• Round-trip engineering
o Raising the environment activities to a first-class workflow is critical. The environment is the tangible embodiment of the project’s process, methods, and notations for producing the artifacts.
• Demonstration-based approach
o Implementation and assessment activities are initiated early in the life cycle, reflecting the emphasis on constructing executable subsets of the evolving architecture.
Q2. Write a short note on iterative workflows.
Iteration consists of a loosely sequential set of activities in various proportions, depending on where the iteration is located in the development cycle. Each iteration is defined in terms of a set of allocated usage scenarios.
The components needed to implement all selected scenarios are developed and integrated with the results of previous iterations. An individual iteration’s workflow, illustrated in the figure given below, generally includes the following sequence:
1. Management: iteration planning to determine the content of the release and develop the detailed plan for the iteration; assignment of work packages, or tasks, to the development team
2. Environment: evolving the software change order database to reflect all new baselines and changes to existing baselines for all product, test, and environment components
3. Requirements: analyzing the baseline plan, the baseline architecture, and the baseline requirements set artifacts to fully elaborate the use cases to be demonstrated at the end of this iteration and their evaluation criteria; updating any requirements set artifacts to reflect changes necessitated by results of this iteration's engineering activities
4. Design: evolving the baseline architecture and the baseline design set artifacts to elaborate fully the design model and test model components necessary to demonstrate against the evaluation criteria allocated to this iteration; updating design set artifacts to reflect changes necessitated by the results of this iteration’s engineering activities
5. Implementation: developing or acquiring any new components, and enhancing or modifying any existing components, to demonstrate the evaluation criteria allocated to this iteration; integrating and testing all new and modified components with existing baselines (previous versions)
6. Assessment: evaluating the results of the iteration, including compliance with the allocated evaluation criteria and the quality of the current baselines; identifying any rework required and determining whether it should be performed before deployment of this release or allocated to the next release; assessing results to improve the basis of the subsequent iteration’s plan
7. Deployment: transitioning the release either to an external organization (such as a user, independent verification and validation contractor, or regulatory agency) or to internal closure by conducting a post-mortem so that lessons learned can be captured and reflected in the next iteration
Q3. Write a short note on joint management reviews.
The four major milestones occur at the transition points between life-cycle phases. They can be used in many different process models, including the conventional waterfall model. In an iterative model, the major milestones are used to achieve concurrence among all stakeholders on the current state of the project. Different stakeholders have very different concerns:
• Customers: schedule and budget estimates, feasibility, risk assessment, requirements understanding, progress, product line compatibility
• Users: consistency with requirements and usage scenarios, potential for accommodating growth, quality attributes
• Architects and systems engineers: product line compatibility, requirements changes, trade-off analyses, completeness and consistency, balance among risk, quality, and usability
• Developers: sufficiency of requirements detail and usage scenario descriptions, frameworks for component selection or development, resolution of development risk, product line compatibility, sufficiency of the development environment
• Maintainers: sufficiency of product and documentation artifacts, understandability, interoperability with existing systems, sufficiency of maintenance environment
• Others: possibly many other perspectives by stakeholders such as regulatory agencies, independent verification and validation contractors, venture capital investors, subcontractors, associate contractors, and sales and marketing teams