Draw.io BPMN 2.0 Implementation

Purpose

This skill enables correct generation of BPMN 2.0 (Business Process Model and Notation) process diagrams in Draw.io mxGraph XML. It enforces BPMN 2.0 shape semantics and prevents the most common AI mistakes: using generic shapes instead of BPMN-specific shapes, mixing sequence flows with message flows, and omitting mandatory pool containers for inter-organizational processes.

Critical Rules (Memorize These)

1. ALWAYS use shape=mxgraph.bpmn.shape for events and gateways -- NEVER use generic ellipse for events or rhombus for gateways. BPMN shapes carry semantic meaning through outline and symbol properties.
2. ALWAYS use dashed lines for message flows -- Message flows between pools MUST have dashed=1;endArrow=open;endFill=0;startArrow=oval;startFill=0;. NEVER use solid arrows for message flows.
3. ALWAYS use solid arrows for sequence flows -- Sequence flows within a pool MUST have endArrow=classic;html=1;. NEVER use dashed arrows for sequence flows.
4. NEVER connect elements in different pools with sequence flows -- Cross-pool communication ALWAYS uses message flows. Sequence flows are ONLY valid within a single pool.
5. ALWAYS wrap activities in a pool or lane -- Every BPMN diagram with more than one participant MUST use pool containers. NEVER place BPMN elements directly on the canvas without a pool when modelling inter-organizational processes.
6. ALWAYS use the correct gateway symbol -- Exclusive (X) uses symbol=exclusiveGw, Parallel (+) uses symbol=parallelGw, Inclusive (O) uses symbol=inclusiveGw, Event-based uses symbol=eventGw. NEVER use a blank diamond.
7. ALWAYS label gateway outgoing edges -- Every edge leaving a gateway MUST have a value attribute describing the condition (except for parallel gateways where all paths execute).
8. ALWAYS set perimeter=ellipsePerimeter on events and perimeter=rhombusPerimeter on gateways -- This ensures edges connect correctly to the shape boundary.

BPMN Element Categories