The second group of collaboration patterns we’ll examine is the customer–supplier patterns. As shown in Figure 4-3, one of the bounded contexts—the supplier—pro‐ vides a service for its customers. The service provider is “upstream” and the customer or consumer is “downstream.”

Figure 4-3. Customer–supplier relationship

Unlike in the cooperation case, both teams (upstream and downstream) can succeed independently. Consequently, in most cases we have an imbalance of power: either the upstream or the downstream team can dictate the integration contract.

This section will discuss three patterns addressing such power differences: the con‐ formist, anticorruption layer, and open-host service patterns.