In order to enable communication with other lanes, pools or even entirely separate processes you need to be able to exchange information. In BPMN, you can use Message Events to model this information exchange. Modeling communication with Message Events in the same diagram uses Message Flow. Message Flow is typically represented by a dashed line arrow between BPMN elements with a black (send) or white (receive) envelope icon. The following BPMN collaboration diagram shows message exchange between two processes.
Message Start Events allow a BPMN process to be started by an incoming message. In the DSF, all BPMN processes are started via messages. Therefore, you will have to include a Message Start Event at the beginning of all of your BPMN models.
Message Intermediate Throwing Events are used to send messages during process execution.
Message Intermediate Catching Events serve as the counterpart to Message Intermediate Throwing Events. Use them whenever you expect to receive a message from another process or organization during execution.
The Message End Event will stop the execution of a BPMN process and finish by sending a message.