2.1 Multiple Viewpoints Work products convey different viewpoints and depth of understanding within a domain. The analysis steps help refine those descriptions into a domain model. We can construct object models for reuse across the domain. In architecture, these viewpoints similarly suggest abstractions reflecting different levels of knowledge. A reference architecture helps us characterize the system structure for software in a domain or product line.
Components capture deeper knowledge, but are based on the reference architecture.
2.2 Engineering Levels of Abstraction Systematic software reuse crosses various engineering boundaries. Reuse is not an end in itself, but rather a means to satisfy the needs of engineering within an organization. We may classify engineering into several levels, depending on the types of activities involved. These work products will include enterprise data and information architecture models, product line definitions, and business models. The work products here are integration architectures and delivered software products.