Elaboration Phase

Elaboration Phase

       The primary purpose of this phase is to complete the most essential parts of the project that are high risk and plan the construction phase. This is the part of the project where technical risk is fully evaluated and/or eliminated by building the highest risk parts of the project. During this phase personnel requirements should be more accurately determined along with estimated man hours to complete the project.

       The complete cost and time frame of the project is more firmly determined. During this phase how the system will work must be considered. Use cases will help identify risks. Steps to take during this phase:

1.       Complete project plan with construction iterations planned with requirements for each iteration.

2.       80% of use cases are completed. Significant use cases are described in detail.

3.       The project domain model is defined. (Don't get bogged down)

4.       Rank use cases by priority and risk. Do the highest priority and highest risk use cases first. Items that may be high risk:

-Overall system architecture especially when dealing with communication between subsystems.

-Team structure.

-Anything not done before or used before such as a new programming language, or using the unified/iterative process for the first time.

 5.      Begin design and development of the riskiest and highest priority use cases. There will be an iteration for each high risk and priority use case.

6.       Plan the iterations for the construction phase. This involves choosing the length of the iterations and deciding which use cases or parts of use cases will be implemented during each iteration. Develop the higher priority and risk use cases during the first iterations in the construction phase.

       As was done on a preliminary level in the previous phase, the value (priority) of use cases and their respective risks must be more fully assessed in this phase. This may be done be either assigning an number to each use case for both value and risk. or categorize them by high, medium, or low value and risk. Time required for each use case should be estimated to the man week. Do the highest priority and highest risk use cases first.

Requirements to be completed for this phase include:

1.       Description of the software architecture. Therefore most use cases should be done, activity diagrams, state charts, system sequence diagrams, and the domain model should be mostly complete.

2.       A prototype that overcomes the greatest project technical risk and has minimal high priority functionality.

3.       Complete project plan.

4.       Development plan.

       There may be an elaboration phase for each high risk use case.

       Considering the various diagrams and charts to be created, when they are created, and the best order to create them in, there seems to be a variety of opinions. This is because in the real world there may be more than one correct solution and there are no hard and fast rules that work everytime. In a way, this flexibility is a strength of UML.

       Some documentation indicates that most use cases should be done before creating a domain model and others indicate that the domain model can be built on a use case by use case basis. A good compromise is to spend a short time on a brief domain model during the elaboration phase, then enhance the domain model as each use case is developed during the elaboration and construction phase iterations.

       Some documentation indicates that activity diagrams and class diagrams should be complete before the domain model is done. It is possible to create some of the diagrams and charts (artifacts) in parallel with each otherCompletion of 80% of use case diagrams.

1.       Completion of 80% of high level use case diagrams.

2.       Completion of expanded use case diagrams for major use cases only.

3.       System sequence diagrams for major use cases

4.       Domain model (Don't get bogged down here with details). Just get a good idea of concepts involved. Use use cases to create the domain model. Any use case that strongly impacts the domain model should be considered and concepts from that use case should be incorporated in the domain model. The initial domain model may be drawn without lines and attributes to avoid too much detail and determine important use cases. The domain model may be refined later as the project analysis continues. If the system is large, domain models should be done on a per use case basis.

5.       Optionally create a glossary of terms for concepts to improve team communication

       After this point the design part of the project begins (although more analysis is done for each use case) and the following will be done in each iteration of the elaboration and construction phases.

1.       Operation contracts based on domain model and use cases.

2.       Collaboration diagrams.

3.       Class diagrams.

4.       Map class and collaboration diagrams to code.

5.       Update the domain model but do not force it to the class diagrams. Considerations during this project should be the following:

       Consider possible significant changes (down the road) to the system during analysis.

       Regarding system functional ability what do you expect to be able to change?

       Elaboration phase plans the necessary activities and required resources and specifies the features and designing the architecture.

Things to do: With the input of the use case model generated from the previous phase, we transform it into a design model via an analysis model. In brief, both an analysis model and a design model are structures made up of classifiers and a set of use-case realizations that describe how this structure realizes the use cases. Classifiers are, in general, "class-like" things.

       The analysis model is a detailed specification of the requirements and works as a first cut at a design model, although it is a model of its own. It is used by developers to understand precisely the use cases as described in the requirements. The analysis model is different from the design model in that it is a conceptual model rather than a blueprint of the implementation.

       Class Diagrams

       Sequence Diagrams

       Collaboration Diagrams

Exit Criteria:

A detailed software development plan, containing:

1.       An updated risk assessment

2.       A management plan,

3.       A staffing plan,

4.       A phase plan showing the number and contents of the iteration

5.       An iterative plan, detailing the next iteration

6.       The development environment and other tools required

7.       A test plan

       A baseline vision, in the form of a set of evalution criteria for the final product

       Objective, measurable evalution criteria for assessing the results of the initial iterations of the construction phase

       A domain analysis model (80% complete), sufficient to be able to call the corresponding architecture 'complete'.

       A software architecture description (stating constraints and limitations)

       An executable architectural baseline.

       During the Elaboration phase the project team is expected to capture a healthy majority of the system requirements. However, the primary goals of Elaboration are to address known risk factors and to establish and validate the system architecture. Common processes undertaken in this phase include the creation of use case diagrams, conceptual diagrams (class diagrams with only basic notation) and package diagrams (architectural diagrams).

       The architecture is validated primarily through the implementation of an Executable Architecture Baseline. This is a partial implementation of the system which includes the core, most architecturally significant, components. It is built in a series of small, timeboxed iterations. By the end of the Elaboration phase the system architecture must have stabilized and the executable architecture baseline must demonstrate that the architecture will support the key system functionality and exhibit the right behavior in terms of performance, scalability and cost.

       The final Elaboration phase deliverable is a plan (including cost and schedule estimates) for the Construction phase. At this point the plan should be accurate and credible, since it should be based on the Elaboration phase experience and since significant risk factors should have been addressed during the Elaboration phase.

       The Lifecycle Architecture Milestone marks the end of the Elaboration phase.