A synchronization enables the splitting or synchronization of control between two or more concurrent actions.
Activity Diagram
Statechart Diagram
Interaction Overview Diagram
Synchronizations are represented as horizontal or vertical lines. You can change the orientation of the symbol by right-clicking it and selecting Change to Vertical or Change to Horizontal from the contextual menu.
A synchronization can be either a:
Fork - Splits a single input flow into several independent output flows executed in parallel:
Join – Merges multiple input flows into a single output flow. All input flows must reach the join before the single output flow continues:
In the following example, the flow coming into the first synchronization is split into two separate flows, which pass through Check Customer Account and Check Stock. Then both flows are merged into a second synchronization giving a single flow, which leads to Process Order: