Assessment functions

Assessment functions run in a completely separate process from the UE4 visualisation.

Communication

All data is exchanged in tthe same format, following these features:

• Data is compliant with the project's JSON schema (opens new window)
• UTF-8 encoded JSON terminated with null byte (\x00) after JSON text
• Sent in TCP/IP packet

A most basic example of simulation message, with some whitespace added for legibility:

{
  "simulationMessage": {
    "meta": {
      "profile": "Operator 1",
      "level": "BasicFlight"
    },
    "frames": [
      {
        "time": 0,
        "position": { "x": 1.248, "y": 2.137, "z": 4.213 },
        "velocity": { "x": 3.388, "y": 0.0, "z": 1.449 },
        "attitude": { "x": 1.05, "y": -15.0, "z": 0.0 },
        "reference": 0.5
      }
    ]
  }
}

And a corresponding response:

{
  "assessmentMessage": {
    "meta": {
      "info": "Assessing reference only"
    },
    "frames": [
      {
        "time": 0,
        "score": [0.8]
      }
    ]
  }
}

The assessment server simply has to fill the score array for every received frame, using received data. The score array contains a measure of operator performance. The mandatory first item is overall operator rating from 0 to 1.

For more detailed examples of messages and assessment servers, see the external-assessment (opens new window) directory in the repository.

Requirements to write an assessment function

Separation into a different process allows the assessment server to be written in any programming language or framework as long as it can provide the following:

• Receiving and sending TCP/IP
• Decoding and encoding UTF-8
• Decoding and encoding JSON