Artifacts, Workers, and Activities
The following subsections describe three key elements of each of the workflows within the Unified Process: artifacts, workers, and activities.
Within the Unified Process, an artifact is any meaningful internal or deliverable chunk of information that plays a role in the development of the system. This book focuses on engineering artifacts, which include things like models, the user-interface prototype, and test evaluations. These artifacts are defined within the workflow chapters, and they're also discussed as deliverables of the phases in which they come into play. Management artifacts, such as the business case and the project plan, are also discussed in the contexts of the five workflows and the four phases. One of the underlying premises of the Unified Process is that a system is not considered fully deliverable until the appropriate artifacts, whether for internal use only or for customers, are reasonably complete.
The Unified Process defines a worker as a role that an individual may play on the project. (The primary difference between a worker and an actor is that an actor is on the outside looking in, whereas a worker is on the inside, perhaps looking out, perhaps not. Also, actors have operational or usage relationships with the system, whereas workers are participants in the development of the system.) Workers produce artifacts, either as individuals or as part of subteams or the team as a whole. One thing to remember is that one person can perform as more than one worker over the course of the project; for example, an analyst may discover use cases and write text for them as well.
Each workflow comprises several activities. In the context of a workflow, an activity is a task that a worker performs in order to produce an artifact. The activities described in this book range from high-level exploration of the concepts and things of interest to the customers (Build the Domain Model) to highly detailed work related to the physical system (Implement a Class).