Chapter 3. Static Structure: Process Description

This chapter describes how the Rational Unified Process is represented. We introduce the key concepts of workers, activities, artifacts, and workflows as well as other elements used in the process's description.

A MODEL OF THE RATIONAL UNIFIED PROCESS

A process describes who is doing what, how, and when. The Rational Unified Process is represented using four primary modeling elements:

Workers: the who
Activities: the how
Artifacts: the what
Workflows: the when

The first three elements are shown in Figure 3-1, and Figure 3-5 shows a workflow.

Figure 3-1. Worker, activities, and artifact

Figure 3-5. Example of a workflow

WORKERS

The central concept in the process is that of a worker. A worker defines the behavior and responsibilities of an individual or a group of individuals working together as a team. The behavior is expressed in terms of activities .the worker performs , and each worker is associated with a set of cohesive activities. "Cohesive" in this sense means those activities best performed by one person. The responsibilities of each worker are usually expressed in relation to certain artifacts that the worker creates, modifies, or controls.

It's helpful to think of a worker as a "hat" that an individual can wear during the project. One person may wear many hats. This distinction is important because it is natural to think of a worker as the individual or the team, but in the Rational Unified Process the term worker refers to the roles that define how the individuals should do the work. A worker performs one or more roles and is the owner of a set of artifacts. Another way to think of a worker is as a part in a play ”a part that can be performed by many actors.

The following are examples of workers:

System Analyst

An individual acting as a system analyst leads and coordinates requirements elicitation and use-case modeling by outlining the system's functionality and delimiting the system.
Designer

An individual acting as a designer defines the responsibilities, operations, attributes, and relationships of one or more classes and determines how they should be adjusted to the implementation environment.
Test Designer

An individual acting as a test designer is responsible for the planning, design, implementation, and evaluation of tests, including generating the test plan and test model, implementing the test procedures, and evaluating test coverage, results, and effectiveness.

Note that workers are not individuals; instead, they describe how individuals should behave in the business and the responsibilities of each individual. Individual members of the software development organization wear different hats, or play different parts or roles. ^[1] The mapping from individual to worker is performed by the project manager when planning and staffing the project. This mapping allows an individual to act as several workers and for a worker to be played by several individuals.

^[1] However, we often write, "The designer of class X does this" when, strictly speaking, we should write, "The individual acting as the designer for class X does this."

In the example shown in Figure 3-2, one individual, Sylvia, can be a Worker: Use-Case Designer in the morning and act as a Worker: Design Reviewer in the afternoon. Paul and Mary are both Designers, although they are likely responsible for different classes or different design packages.

Figure 3-2. People and workers

For each worker, a set of expected skills must be provided by the individual who is designated as the worker. Sylvia must understand how to design a use case and how to review a part of the design.

Workers are usually denoted in the process prefixed with the word Worker, as in Worker: Integration Tester. Appendix A lists all workers defined in the Rational Unified Process