BPMN 1.2 provides a mapping from a “valid” BPMN diagram to BPEL, such that an engine can execute the process. The 1.2 specification provides only contained verbal descriptions of the graphic notations elements and modeling rules. This leads to misleading and confusions in the translation process.
BPMN 2.0 represents the biggest revision of BPMN since its inception. BPMN 2.0 received a formal definition in the form of a metamodel, that is a precise definition of the constructs and rules needed for creating specific models.
Some of the main changes that the BPMN versions 2.0 brought with them are among others:
The addition of a Choreography diagram.
The addition of a Conversation diagram.
Non-interrupting Events for a Process.
Event Sub-processes for a Process.
The major technical changes include:
A definition of the process execution semantics.
A formal metamodel as shown through the class diagram figures.
Interchange formats for abstract syntax model interchange in both XML Metadata
Interchange (XMI) and XML Schema Definition (XSD).
Interchange formats for diagram interchange in both XMI and XSD.
Extensible Stylesheet Language Transformations (XSLT) between the XMI and XSD formats.
Other technical changes include:
Reference Tasks are removed. These provided reusability within a single diagram, as compared to Global Tasks, which are resuable across multiple diagrams. The new Call Activity can be used to reference a Global Task or another Process to be used within a Process (instead of Reference Tasks).
Because of the version 2.0 updates, the number of elements more than doubled from 55 elements to 116. Many of these new elements were applied to modeling interactions between processes and/or entities, such as the new choreography diagram.
BPMN 2.0.2, released in December 2013, included only minor modifications in terms of typo corrections and a change in clause 15.