Advanced Concepts

This chapter covers the following topics:

1. Chunking information: view packets, refinement, and descriptive completeness. Documentation for a view cannot show all its information at once; the result would be hopelessly complex and confusing. Architects break their information up into digestible chunks called view packets. Section 6.1 discusses view packets and how they let a stakeholder move around the documentation of the system, up and down in levels of granularity, and from view to view, all while maintaining a coherent picture of the whole.
2. Using context diagrams. A context diagram establishes the boundaries for the information contained in a view packet. A context diagram for the entire system defines what is and is not in the system, thus setting limits on the architect's tasks. Context diagrams are discussed in Section 6.2.
3. Documenting combined views. Prescribing a given set of rigidly partitioned views is naive; there are times and good reasons for combining two or more views into a single combined view. Indeed, combined views are often responsible for an architecture's conceptual integrity, because only views that resemble one another in fundamental ways can be fruitfully merged. On the other hand, combined views, especially views that unintentionally mix concerns, are also the source of the vast majority of confusion in carelessly documented architectures. These topics are discussed in Section 6.3.
4. Documenting variability and dynamism. Some architectures incorporate built-in variability to let a group of similar but architecturally distinct systems be built from them. Other architectures are dynamic, in that the systems they describe change their basic structure while they are running. Section 6.4 discusses documenting views of variable and dynamic architectures.
5. Creating and documenting new styles. Just as a fixed set of views is naive, so too is a fixed set of styles. Styles, like design patterns, are a growing body of knowledge, and new and useful ones are emerging all the time. What are the architect's obligations when creating or documenting a new or modified style? Section 6.5 discusses these obligations.