Message Flows

Message Flow
A Message Flow is used to show the flow of Messages between two Participants that are prepared to send and receive them.
— BPMN 2.0.2 Standard, 9.4, Message Flow

Message Flows connect model the information flow between two entities represented as pools. Information between two pools can only be exchanged via message flows. A message flow can be attached to pools, activities or message events. The order of message exchanges can be specified by combining message flows and sequence flows.

Executable business processes usually do not make use of message flows since they are not considered when executing the process. Using them only serves documentation purposes.