Having identified a wide variety of upstream and downstream influences in Chapter 9, in this ­chapter we select severalupstream and downstream influences to explore in more detail. Our intent is not to develop a framework for each, but to stimulate the reader to consider the relevant coupling between these influences and the architecture. Which influences will meaningfully reduce ambiguity? Which influences will help us select among candidate architectures? In this context, it is helpful to think about influences on architectural decisions (Box 10.1).

We will revisit architectural decisions in detail in Part 4, but it is a helpful concept to carry while discussing upstream and downstream influences, because we will have to answer questions about the magnitude of the impact of each of the influences. (For example, will marketing affect whether the car is two-wheel or four-wheel drive?)

With these questions in mind, we begin our discussion with upstream influences, where we pose the question “What upstream influences impact architectural decisions?” We ask it in four focus areas, beginning with corporate strategy in Section 10.2, followed by ­marketing, regulation, and technology infusion in Sections 10.3 through 10.5. The second half of the chapter focuses on downstream influences. Whether it be capturing relevant information about the manufacturing capabilities of the enterprise or planning a series of derivative products, it is important to consider the downstream influences on architectural decisions. This is a generalization of the idea that the product design community calls Design for X (DFX), ^[1] where X is whatever is downstream of design (manufacturing, service, upgrades, and so on). Implementation, operations, Design for X, and product evolution are addressed in Sections 10.6 through 10.9. We then summarize these upstream and downstream influences in an iterative model called the “Product Case.”