Most people tend to model systems using services and entities. They forget that entities exist over time, and transition from one state to another. Often, these states are modeled as status flags on the entity. Unfortunately, this doesn't really work out in practice. It's like trying to describe a complicated customer fulfillment process using a UML sequence diagram - it's missing a few things: who is doing what, and - most importantly - when. There is a better way: a workflow engine can be used to extricate the process state from your application, and manage it. In this talk, we will explore the basics of workflow engines, and of process oriented architectures. We will introduce Activiti - a powerful, lightweight, embeddable workflow engine created by Tom Baeyans (the creator of jBPM) from Alfresco and explore its use in a Spring-based application