Lanes within the Pool. In this situation, each Lane would represent two participants and a direction of travel between them. They may also be shown as two or more Abstract Processes interacting through Message Flow (as described in the previous section). These processes can be modeled separately or within a larger BPMN Diagram to show the Associations between the collaboration process activities and other entities. If the collaboration process is in the same Diagram as one of its corresponding private business process, then the activities that are common to both processes can be associated. Within and between these three BPMN sub-models, many types of Diagrams can be created. The following are the types of business processes that can be modeled with BPMN (those with asterisks may not map to an executable language): High-level private process activities (not functional breakdown)* Detailed private business process As-is or old business process* To-be or new business process Detailed private business process with interactions to one or more external entities (or “Black Box” processes) Two or more detailed private business processes interacting Detailed private business process relationship to Abstract Process Detailed private business process relationship to Collaboration Process Two or more Abstract Processes* Abstract Process relationship to Collaboration Process* Collaboration Process only (e.g., ebXML BPSS or RosettaNet)* Two or more detailed private business processes interacting through their Abstract Processes and/or a Collaboration Process BPMN is designed to allow all the above types of Diagrams. However, it should be cautioned that if too many types of sub-models are combined, such as three or more private processes with message flow between each of them, then the Diagram may become difficult to understand. Thus, the OMG recommends that the modeler pick a focused purpose for the BPD, such as a private or collaboration process. Comparison with other process modeling notations Event-driven process chains (EPC) and BPMN are two notations with similar expressivity when process modeling is concerned. A BPMN model can be transformed into an EPC model. Conversely, an EPC model can be transformed into a BPMN model with only a slight loss of information. A study showed that for the same process, the BPMN model may need around 40% less elements than the corresponding EPC model, but with a slightly larger set of symbols. The BPMN model would therefore be easier to read. The conversion between the two notations can be automated. UML activity diagrams and BPMN