Reading WebSocket Locations

View WebSockets Reference View the WebSockets Reference.

View TMM API Sample Code Sample code for TMM-API integrations is available on GitHub, including projects for Android, iOS and .NET MAUI.

TMM serves location data over WebSocket connections. TMM provides two versions of the WebSocket API: V1 and V2.

• WebSocket V1 (Deprecated)
• WebSocket V2

The process of reading location data from a WebSocket connection involves connecting to the appropriate WebSocket endpoint and handling incoming messages that contain location updates. Location data is in JSON format.

To read location data from a WebSocket connection, you need to establish a connection to the appropriate WebSocket endpoint and then listen for incoming messages that contain location updates. The following example demonstrates how to do this in C#.

C#

internal async Task ReadPositionsAsync(CancellationToken cancel)
{
  try
  {
    // Open an insecure connection to WebSocketV2.
    Uri uri = new Uri($"ws://localhost:9639");
    using ClientWebSocket client = new ClientWebSocket();
    await client.ConnectAsync(uri, cancel);

    while (!cancel.IsCancellationRequested)
    {
      // Will continue to run as long as the WebSocket is connected, unless canceled.

      using MemoryStream messageBuffer = new();
      var buffer = new ArraySegment<byte>(new byte[1024]);
      WebSocketReceiveResult result;
      bool closed = false;

      // A single message may arrive across multiple WebSocket frames.
      do
      {
        result = await client.ReceiveAsync(buffer, cancel);

        if (result.MessageType == WebSocketMessageType.Close)
        {
          await client.CloseAsync(WebSocketCloseStatus.NormalClosure, "Closing", CancellationToken.None);
          closed = true;
          break;
        }

        if (result.Count > 0)
        {
          messageBuffer.Write(buffer.Array!, buffer.Offset, result.Count);
        }
      }
      while (!result.EndOfMessage);

      if (closed)
      {
        break;
      }

      if (result.MessageType == WebSocketMessageType.Text && messageBuffer.Length > 0)
      {
        // parse the location data.
        string jsonString = Encoding.UTF8.GetString(messageBuffer.ToArray());
        JsonNode? jnode = JsonNode.Parse(jsonString);
        if (jnode is not null)
        {
          double? latitude = jnode["latitude"]?.GetValue<double>();
          double? longitude = jnode["longitude"]?.GetValue<double>();
          double? altitude = jnode["altitude"]?.GetValue<double>();
        }
      }
    }
  }
  catch (TaskCanceledException)
  {
  }
}