Integrating with legacy systems

Delivering new business value at a faster pace is the major goal of digital transformation. Achieving this goal usually involves migrating off existing (that is, legacy) systems. This migration process does not happen overnight. Therefore, it is crucial that we do not put the existing systems at risk. They need to continue to deliver business value until they are retired.To provide this continuity of business, we follow an event-first migration approach that iteratively adds new business value and incrementally upgrades existing features, until we no longer need the legacy systems. We refer to this approach as the Strangler pattern. We will discuss the business value supporting this approach in Chapter 13, Don't Delay, Start Experimenting. In this section, we will cover the tactical aspects of integrating with a legacy system.There are two main objectives for this approach:We do not want to modify the existing systems, if at all possible. This is consistent...