Release v0.9: Support for almost every BPMN element, exception: Groups are not supported yet. Soon to come.

BPMN Layouter

This BPMN auto-layouter allows you to make nice looking BPMN diagrams by one click.
It comes as a plugin for the Eclipse-based Camunda Modeler and as a Eclipse-independent class that receives the BPMN diagram as a graph and returns it with new node and edge positions.

The layout algorithm (actually a couple of algorithms) is based on KIELER, a graph and layout framework by the University of Kiel - more specifically KLay Layered which is part of the KIELER pragmatics project.

KLay Layered is based on 5 layout phases. You can get a introduction to these layout phases here (theses in German, see chapter 2.3, page 7 ff) or here (theses in English, see chapter 2.4, page 16 ff).

KIELER is a very modular and well-documented project. It uses intermediate processors between the main layout phases. This makes the layout process rather complex, but also very flexibel.

So much about KIELER, now about this project:

eu.ml82.bpmn_layouter.camunda_modeler

This package contains the Eclipse plugin. It translates the Graphiti graph to a KIELER KGraph object (DiagramLayoutManager) and after layouting back again to Graphiti (LayoutCommand).

KGraph is KIELERS generic graph format. In this package the transformation from KLay to LGraph is also invoked. This is a fully KIELER internal process without any BPMN-specific code. LGraph is a special graph class for KIELERS KLay Layered algorithm.

This package is based on de.cau.cs.kieler.kiml.graphiti with some BPMN-specific adjustments.

eu.ml82.bpmn_layouter.core

This is the main layout package. KlayLayeredForBpmn.doLayout(final LGraph lgraph, PosType posType) expects an LGraph object and returns a layouted LGraph object.

The LGraph object needs the following BPMN-specific information:

• BpmnProperties.BOUNDARY_EVENT_DUMMY_EDGE marks a dummy edge between a boundary event and the activity it is attached to
• BpmnProperties.ELEMENT_TYPE marks special BPMN elements (Gateway, Pool, Lane, Subprocess, Message Flow)
• LayoutOptions.EDGE_TYPE needs to be set to EdgeType.UNDIRECTED for undirected associations.

When working with the LGraph layout results, you have to note that you can set posType to PosType.RELATIVE or PosType.ABSOLUTE. PosType.RELATIVE returns the layout results as relative positions which means:

• Node position are relative to their parent node. Example: A task within a pool has the y-position 35, the pool's y-position is 250, so the task's absolute y-position is 285.
• Port positions (the position where an edge is attached to a node) are relative to the node they belong to.
• Edge bendpoints are relative to source node's container.
• If edge source and target do not belong to the same container, the target port's position is relative to the source port. In case of PosType.ABSOLUTE all positions are absolute, with one exception:
• Port positions (the position where an edge is attached to a node) are relative to the node they belong to.

That's it, everything else is just a plain LGraph with nodes (LNode) and edges (LEdge).

The BPMN part of the layouter is mainly packed in intermediate layout processors. The detailed description is coming soon:

Pools / Lanes

Message Flows

Boundary Events

Artifacts

Groups

Dependencies

• KIELER Pragmatics 2015-06
• Camunda Modeler 2.7.0

Build

You can build via Maven or in Eclipse by clicking "Build All" in the site.xml settings dialog.

Compiled Plugin

You can install this plugin via its update site

Eclipse-independent bundle

The core layout function has some indirect dependencies on Eclipse (mainly EMF) on the plugin level. Though on class level there are no Eclipse dependencies.
Using the Maven assembly plugin you can build a bundle with all class-level dependencies by running
mvn -f pom_bundle.xml dependency:unpack-dependencies assembly:single in the eu.ml82.bpmn_layouter.core folder.