WORKFLOWS

A mere enumeration of all workers, activities, and artifacts does not quite constitute a process. We need a way to describe meaningful sequences of activities that produce some valuable result and to show interactions between workers. A workflow is a sequence of activities that produces a result of observable value. In UML terms, a workflow can be expressed as a sequence diagram, a collaboration diagram, or an activity diagram. We use a form of activity diagrams in this book. Figure 3-5 is an example of a workflow. ^[2]

^[2] Strictly speaking, our core workflows are workflow classes, of which there are many possible workflow instances.

Note that it is not always possible or practical to represent all the dependencies between activities. Often, two activities are more tightly interwoven than shown, especially when they involve the same worker or the same individual. People are not machines, and the workflow cannot be interpreted literally as a program that people are to follow exactly and mechanically.

There are many ways to organize the set of activities in workflows. We have organized the Rational Unified Process using the following:

Core workflows
Workflow details
Iteration plans

Core Workflows

There are nine core process workflows in the Rational Unified Process, and they represent a partitioning of all workers and activities into logical groupings: areas of concern, or disciplines (see Figure 3-6). The core process workflows are divided into six core engineering workflows and three core supporting workflows.

Figure 3-6. Nine core process workflows

The engineering workflows are as follows :

Business modeling workflow
Requirements workflow
Analysis and design workflow
Implementation workflow
Test workflow
Deployment workflow

The three core supporting workflows are as follows:

Project management workflow
Configuration and change management workflow
Environment workflow

Although the names of the six core engineering workflows may evoke the sequential phases in a traditional waterfall process, you will see in Chapter 4 that the phases of an iterative process are different and that these workflows are revisited again and again throughout the lifecycle. The actual complete workflow of a project interleaves these nine core workflows and repeats them with various emphases and levels of intensity at each iteration. The core workflows are discussed in detail in Chapters 7 through 15.

Workflow Details

Each of the core workflows covers a lot of ground. To break them down, the Rational Unified Process uses workflow details to express a specific group of closely related activities. For example, the activities are performed together or in a cyclical fashion; or they are performed by a group of people working together in a workshop; or they produce an interesting intermediate result. Workflow details also show information flows ”the artifacts that are input to and output from the activities ”showing how activities interact through the various artifacts.

Iteration Plans

Iteration plans are another means of presenting the process, describing it more from the perspective of what happens in a typical iteration. They are actually the closest to what a workflow engine would handle. You can look at them them as instantiations of the process for one given iteration, selecting the activities that will be effectively run during the iteration, and replicating them as necessary. There are an infinite number of ways you can instantiate the process. The Rational Unified Process contains descriptions of a few typical iteration plans. They are given primarily for pedagogical purposes, as you can see with the few examples given in Chapter 16.