All big systems become manageable when we divide their complexities into smaller pieces, which makes them easier to understand and implement. BPM systems apply this by dividing each function in a different module and interconnecting them within a special structure that (in the case of jBPM6) looks something like the following figure:
BPMS' internal structure
Each component in the preceding figure resolves one particular function inside the BPMS architecture, and we'll see a detailed explanation on each one of them.
The execution node, as seen from a black box perspective, is the component that receives the process definitions (a description of each step that must be followed; from here on, we'll just refer to them as processes). Then, it executes all the necessary steps in the established way, keeping track of each step, variable, and decision that has to be taken in each process's execution (we'll start calling these process instances).
The execution...