A system and method may generate executable models having message sending objects and message receiving objects. A message may include a fixed data payload, and the message may persist for only a determined time interval of a total execution or simulation time of model. Message queues may be established for the messages, and the queues may have attributes. The model may include a state-based portion having states and transitions. States may be configured to generate and send messages, and to receive and process messages. In addition, transitions may be guarded by particular messages. The system and method also may generate standalone code, such as source code, for the model. The standalone code may include code that establishes a message passing service to support the sending and receiving of messages.