10.1 - The Message Interface

This section focuses on the message-passing mechanism for exchanging interface messages.

VR-Forces applications communicate all information through DIS PDUs or HLA RPR FOM objects and interactions. In addition to the standard protocol messages, VR-Forces sends messages that VR-Forces applications use to communicate with one another, such as scenario management, creating and deleting objects and simulation objects, and executing plans. This data is sent using instances of the DtVrfMessageInterface (vrfMsgIf.h) class. VR-Forces applications have a DtVrfMessageInterface, maintained by the DtSimManager class. Applications that use the Remote Control API also have a DtVrfMessageInterface, maintained by the DtVrfRemoteController class.The DtVrfMessageInterface sends and receives DtSimInterfaceMessages (ifaceMsg.h). The DtVrfMessageInterface is initialized with a pointer to the DtExerciseConnection and a simulation address. The actual DtSimInterfaceMessages are wrapped inside of VR-Link DtDataInteractions. Through this mechanism, VR-Forces effectively extends the DIS and HLA RPR FOM protocols to support additional application-specific messages.

A DtSimInterfaceMessage has a pointer to an instance of a DtSimInterfaceContent (ifaceCont.h). All interface messages are derived from DtSimInterfaceContent. The DtSimInterfaceMessage acts as an ‘envelope’ capable of containing various kinds of content. The different kinds of interface content types are identified by integers. The integers for DtSimInterfaceContent types are specified in msgTypes.h.

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