Okay, we just got the minimum required introduction to Spring Web Flow concepts; there are plenty of advanced concepts out there to master in Spring Web Flow. We are not going to see all those things, because that itself deserves a separate book. As of now, this is enough to understand the checkout-flow.xml flow definition file. But before that, we will provide a quick overview of our checkout flow. The following diagram will give you the overall idea of the checkout flow that we just implemented:
Our checkout flow diagram has a start state and an end state; each rounded rectangle in the diagram defines an action state and each double-line-bordered rounded rectangle defines a view state. Each arrowed line defines transition, and the name associated with it defines the event that causes that particular transition. The checkout-flow.xml file just contains this flow in an XML representation.
If you open the checkout-flow.xml file, the first tag you encounter within...