Hook Execution

When running simulations, you may want to run programs before or after the simulation execution itself. Triggers currently only offer events during a simulation, since many actions are only available after simulation agents are connected and the simulation has started.

The Cloe engine can execute hooks at two different times:

• pre-connect

• post-disconnect

These can be used in the engine section of the stack file:

• /engine/hooks/pre_connect as an array of command actions

• /engine/hooks/post_disconnect as an array of command actions

For a description of the command action, see Built-in Actions.

Here is an example bootstrap stack file, which is included in the list of input stack files when we want to automatically start and stop the VTD simulator:

{
  "version": "4",
  "engine": {
    "hooks": {
      "pre_connect": [
        { "path": "${VTD_LAUNCH}", "args": [ "stop" ] },
        {
          "path": "${VTD_LAUNCH}",
          "args": [
            "-l", "/tmp/vtd.log",
            "start",
            "--vtd-setup-cloe", "Cloe.noGUInoIG",
            "--vtd-project", "${THIS_STACKFILE_DIR}/../contrib/projects/cloe_tests"
          ]
        }
      ],
      "post_disconnect": [
        { "path": "${VTD_LAUNCH}", "args": ["stop"] }
      ]
    }
  }
}

Note that we can use environment variables as well as special variables THIS_STACKFILE_DIR and THIS_STACKFILE_FILE, unless you have interpolation disabled. See Variable Interpolation for more information on this.

Hooks can be disabled from the command line (or via an environment variable):

--no-hooks

Disable execution of hooks.

--secure, -s, CLOE_SECURE_MODE=1

Enable secure mode, which disables hooks, disables interpolation, and prevents loading files from the system.

See cloe-engine --help for up-to-date information for your version of Cloe.