- Best Practices—The Foundation of RUP
- RUP Key Concepts
- RUP as a Process Framework
- Summary
This chapter is from the book
This chapter is from the book
This chapter is from the book
RUP Key Concepts
RUP can be described in terms of two dimensions: time and content. Figure 3.1 provides a graphical representation of these dimensions. The horizontal axis represents time and shows the life cycle aspects of the process. This dimension is described in terms of phases and iterations. The vertical axis represents content and shows the disciplines, which logically group the process content.
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Figure 3.1 Time and Content Dimensions of RUP
As the "humps" in Figure 3.1 illustrate, the relative emphases of the disciplines change over the life of the project. For example, in early iterations more time is spent on Requirements, and in later iterations more time is spent on Implementation. Configuration and Change Management, Environment, and Project Management activities are performed throughout the project. Keep in mind, however, that all disciplines are considered within every iteration. We discuss the iterative nature of the disciplines in more detail within each of the process chapters (Chapters 6–9).
An effective software development process should describe who does what, how, and when. RUP does exactly that in terms of the following key concepts:
Roles: The who
Artifacts: The what
Activities: The how
Phases, iterations, disciplines and workflow details: The when
The RUP key concepts and their relationships are shown in Figure 3.2.
A software development project moves through a number of phases each of which is divided into a number of iterations. Within each iteration, we consider the various disciplines. The activities within a discipline are described in terms of workflow details. Workflow details describe activities that are usually performed together, the roles that perform those activities, and the resulting artifacts.
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Figure 3.2 RUP Key Concepts
Artifacts
An artifact3 is a piece of information that is produced and/or used during the execution of the process. Artifacts are the tangible by-products of the process. The deliverables that end up in the hands of the customers and end users are only a subset of the artifacts that are produced on a project.
Artifacts may take various shapes or forms.
A model, such as a Use-Case Model or Design Model4, which contains model elements
A model element, such as a Use Case, Design Class, or Design Subsystem, which is part of a model
A document, such as a Software Architecture Document
Source code
An executable
A project plan
Artifacts are the responsibility of a single role. Roles use artifacts as input to activities, and roles produce or modify artifacts in the course of performing activities.
Artifacts are represented in RUP (and in the J2EE Developer Roadmap) using graphical symbols. Some examples of RUP artifacts are shown in Figure 3.3.
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Figure 3.3 Examples of RUP Artifacts
Roles
A role defines the behavior and responsibilities of an individual, or a set of individuals working together as a team, within the context of a software development organization. A role is responsible for one or more artifacts and performs a set of activities. For example, the designer role defines the responsibilities, operations, attributes, and relationships of one or several Design Classes, and determines how they will be implemented.
It is important to emphasize that roles are not individuals. Individuals may play multiple roles ("wear multiple hats") and multiple individuals may play a single role. The Project Manager performs the assignment of individuals to roles when planning and staffing the project.
Roles are also represented in RUP graphically as shown in Figure 3.4.
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Figure 3.4 Examples of RUP Roles
Activities
An activity is a unit of work that provides a meaningful result in the context of the project. It has a clear purpose, which usually involves creating or updating artifacts. Every activity is assigned to a specific role. Activities may be repeated several times, especially when executed in different iterations.
Activities are composed of one or more steps. For example, the activity Implement Design Elements of the Implementation discipline in the J2EE Developer Roadmap has the following steps:
Implement Design Subsystems
Implement Framework Components
Implement Design Classes and Interfaces
Implement Deployment Elements
An activity is displayed in RUP as shown in Figure 3.5.
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Figure 3.5 Examples of Activities
Disciplines
A discipline is a collection of activities that are related to a major "area of concern" within the overall project. Disciplines group activities logically. As we show in Figure 3.1, RUP is organized around nine disciplines. Table 3.1 provides a brief description of each of these disciplines.
Table 3.1 RUP Disciplines
|
RUP Discipline |
Brief Description |
|
Business Modeling |
The purpose of the Business Modeling discipline is to:
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Requirements |
The purpose of the Requirements discipline is to:
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Analysis and Design |
The purpose of the Analysis and Design discipline is to:
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Implementation |
The purpose of the Implementation discipline is to:
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Test |
The purpose of the Test discipline is to:
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Deployment |
The purpose of the Deployment discipline is to:
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Configuration and Change Management |
The purpose of the Configuration and Change Management discipline is to: |
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Project Management |
The purpose of the Project Management discipline is to:
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Environment |
The purpose of the Environment discipline is to:
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Workflow Details
It is not enough to describe the artifacts produced by a process and the roles that perform the activities that produce these artifacts. A process also needs to provide guidance on what activities are performed together and the order in which the activities are performed. Such guidance can be expressed in a set of workflows. A workflow is a sequence of activities that produces a result of observable value.
In RUP, the process is described at two levels: the discipline level and the workflow detail level. A workflow detail is a grouping of activities that are often performed "together" to produce a specific result. In particular, workflow details describe groups of activities performed together in a discipline.
The workflows for the RUP disciplines and workflow details are described using Unified Modeling Language (UML) activity diagrams. Discipline diagrams contain the workflow details of the discipline. The diagram for the Implementation discipline, as configured in the J2EE Developer Roadmap, is shown in Figure 3.6. This discipline consists of two workflow details: Structure the Implementation Model and Implement Design Elements.
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Figure 3.6 Implementation Discipline Workflow
Within a workflow detail, activities may be performed in parallel, and each activity may affect more than one artifact. Workflow detail diagrams show the key artifacts, activities, and roles involved in the workflow detail. The content of the Implement Design Elements workflow detail, as tailored in the J2EE Developer Roadmap, is shown in Figure 3.7. This workflow detail consists of three activities: Implement Design Elements, Perform Unit Tests, and Review the Implementation.
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Figure 3.7 Implement Design Elements Workflow Detail
Iterations
Iterative development is a key characteristic of successful software development projects. Within an iterative software development life cycle, several passes are made through each of the disciplines. Each pass is called an iteration. An iteration is a distinct, time-boxed sequence of activities that results in a release (internal or external) of an executable product. As the project progresses, releases evolve from a subset of the final product to the final system. An iterative development process is similar to "growing" software, where the end product matures over time. Each iteration results in a better understanding of the requirements, a more robust architecture, a more experienced development organization, and a more complete implementation.
Figure 3.8 illustrates how the focus of a project shifts across successive iterations. The size of the boxes within each of the disciplines illustrates the relative time spent performing the activities within that discipline. Each discipline is addressed during every iteration, but the relative emphasis shifts as the project progresses from Requirements to Analysis and Design to Implementation to Test, and finally to Deployment.
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Figure 3.8 An Iterative Life Cycle
The following list provides some important characteristics of a successful iteration.
The iteration has clear evaluation criteria.
The iteration has a planned capability that is demonstrable.
The iteration is concluded by a minor milestone, where the result of the iteration is assessed relative to the objective success criteria of that particular iteration.
During the iteration, artifacts are updated (artifacts evolve with the system).
During the iteration, the system is integrated and tested.
Phases
There is more to an iterative development process than a stream of iterations. There must be an overall framework in which the iterations are performed that represents the strategic plan for the project and drives the goals and objectives of each of the iterations. Such a framework is provided by phases. Phases provide well-defined business milestones that ensure that the iterations make progress and converge on a solution, rather than just iterating indefinitely.
Phases and iterations together provide the foundation for iterative development. The objectives of each phase are achieved by executing one or more iterations within the phase. Each phase concludes with a major milestone and an assessment to determine whether the objectives of the phase have been met. A satisfactory assessment allows the project to move to the next phase. Iterations are time-based (they are of a fixed duration), whereas phases are goal-based. A phase cannot be time-boxed since the completion of a phase is assessed based on the state of the project.
In RUP, the software development life cycle is decomposed into four sequential phases: Inception, Elaboration, Construction, and Transition. These phases and their milestones are shown in Figure 3.9.
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Figure 3.9 RUP Phases and Milestones
Inception
The Inception phase is where the "business case" for the project is established, and where concurrence among all stakeholders on the objectives for the project is also established. Inception is where we focus is on ensuring that the project is both valuable and feasible. The primary objectives and milestone criteria of the Inception phase are summarized in Table 3.2.
Table 3.2 Inception Phase Objectives and Evaluation Criteria
|
Primary Objectives |
Milestone Evaluation Criteria |
|
Establish the project's scope. |
Stakeholders concur with the scope definition. |
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Establish the project's acceptance criteria. |
Stakeholders concur with the project acceptance criteria. |
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Identify the features of the system, and select those that are critical. |
Stakeholders concur that the right set of requirements has been captured and there is a shared understanding of the requirements. All requirements are prioritized. |
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Estimate the overall cost and schedule for the entire project (more detailed estimates for the Elaboration phase that will immediately follow). |
Stakeholders concur that the cost/schedule estimates, priorities, risks, and development processare appropriate. |
| Set up the supporting environment for the project (for example, hardware, software, process, resources). | The supporting environment is in place. |
Elaboration
The Elaboration phase is where the software architecture is established that provides a stable foundation for the design and implementation that is performed during the Construction phase. The primary objectives and milestone criteria of the Elaboration phase are summarized in Table 3.3.
Table 3.3 Elaboration Phase Objectives and Evaluation Criteria
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Primary Objectives |
Milestone Evaluation Criteria |
|
Ensure that the architecture, requirements and plans are stable. Establish a baselined architecture. |
The product vision, requirements and baselined architecture are stable. |
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Ensure that the risks are sufficiently mitigated to be able to predictably determine the cost and schedule for the completion of the development. |
The major risk elements have been addressed and have been credibly resolved. |
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Demonstrate that the baselined architecture will at an acceptable cost and within an acceptable timeframe. |
All architecturally significant aspects of the system, support the requirements of the systemand selected areas of functionality, have been evaluated in an evolutionary prototype7. |
Construction
The Construction phase is where the remaining requirements are clarified and where development of the system is completed based on the baselined architecture established during the Elaboration phase. Between the Elaboration and Construction phases, the focus shifts from understanding the problem and identifying key elements of the solution, to the development of a deployable product. The primary objectives and milestone criteria of the Construction phase are summarized in Table 3.4.
Table 3.4 Construction Phase Objectives and Evaluation Criteria
|
Primary Objectives |
Milestone Evaluation Criteria |
|
Achieve useful versions (alpha, beta, and other test releases) in a timely fashion. |
The system has been developed in line with the expectations specified in the phase plan and iteration plans. |
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Complete the analysis, design, implementation and testing of all required functionality. |
All required functionality has been incorporated into the system. |
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Make sure the system is ready to be deployed into the end user's environment. |
The system has met all acceptance criteria when tested in the development environment. |
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Successfully roll out the system to the delivery channels. |
The system has passed the formal acceptance criteria in the end user's environment. |
Transition
The Transition phase is where we ensure that the software is available to, and accepted by, its end users. This is where the system is deployed into the user's environment for evaluation and testing. The focus is on fine-tuning the product, and on addressing configuration, installation, and usability issues. All the major structural issues should have been worked out much earlier in the project's life cycle. By the end of the Transition phase, the project should be in a position to be closed out. The primary objectives and milestone criteria of the Transition phase are summarized in Table 3.5.