Explain the execution flow of a distributed transaction across microservices in AppDynamics?

In a microservices architecture, a single user-facing request often fans out across many independently deployed services, and AppDynamics reconstructs that entire path as one logical Business Transaction rather than a set of disconnected per-service metrics.

Each service's own agent only knows about its own segment of the work; none of them individually sees the whole picture. It's the Controller, after receiving every tier's separately-reported segment tagged with the same correlation identifier, that stitches them together into a single transaction snapshot and a single flow-map path.

This is what lets a team looking at one slow checkout request see, in one view, that the Order Service itself was fast but it was blocked waiting nearly a full second on the Payment Service — a conclusion that would be nearly impossible to reach by looking at each service's isolated dashboards separately, since no single dashboard shows the full chain end to end.