HLA

HLA, as a middleware, provides a way to connect Morse to various other simulator engines, using HLA as standard way to communicate between theses tools. As Python interface is not defined for HLA, the Morse implementation works only with the CERTI implementation of HLA. Moreover, currently, Morse deals only with a subset of the full HLA standard:

  • basic federation management
  • declaration management (attribute part only, i.e. datastream in the Morse language)
  • object management (note that, in the current state, Morse does not create new object when it receives a Discover Object Instance but links a pre-existing object with this HLA instance
  • time management

In particular, it means that in the current state, Morse does not support:

  • interactions
  • data distribution management
  • ownership management

Warning

In the current state, no SOM (Simulation Object Model) has been specified, so it is up to the specific users to develop it, with the associated Morse bindings.

certi_test_input and certi_test_output are provided for example, and are supposed to work with the billard example provided by CERTI.

Datastreams interface

The mapping between Morse and HLA vocab is the following:

  • publishObjectClass and UpdateAttributeValues correspond to an output stream
  • subscribeObjectClassAttributes and reflectAttributeValues correspond to an input stream.

Service interface

It is unsupported for the moment.

Configuration specificities

The following variables permit to configure HLA behaviour:

  • fom: Mandatory : a string representing the FOM (Federation Object Model) used for this simulation
  • name: Mandatory : a string representing the name of this simulation in the federation
  • federation: Mandatory : the name of the federation to join
  • sync_point: Optional : the name of the initial synchronisation point used for the federation. If it is not present, Morse assumes there is no need to initial synchronisation
  • sync_register: Optional : if a sync_point is defined, and this variable is true, then this instance of Morse will register the sync_point to the RTIG, and the user should start the simulation by pressing Enter. The default is False.
  • time_sync: Optional : a boolean indicating if the simulation is in ‘Best-effort’ mode or synchronised by HLA. The default value is False.
  • timestep: Optional : a float indicating how much logic time elapse each game loop. Do not set it if you use physics from Blender (or sensors relying on Blender time !.
  • lookahead Optional : a flow indicating the lookahead used by HLA. The default value is timestep.
  • stop_time: Optional : a float indicating when the simulation must stop. If not configured, the simulation continues infinitely. It only works if time_sync is enabled.

You need to pass them to the configure_stream_manager method in the following way:

env = Environment('...')
env.configure_stream_manager(
        'hla',
         fom = 'Test.fed', name = 'Morse', federation = 'Test',
         sync_point = 'Init', time_sync = True)

Files

  • Python: $MORSE_ROOT/src/morse/middleware/hla_datastream.py

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