👀 README now have mentions about the expected/supported payloads in pub/sub messaging

Author: luismr

README.md

@@ -293,6 +293,68 @@ app:
    - `ReadWriteRoutingAspect`: Sets the context based on transaction type
    - `DbContextHolder`: Thread-local holder for the current context
 
+## Message Payloads
+
+The application uses two main DTOs for message communication:
+
+### PingDTO
+Used to publish flight position updates to the flight-tracker-event-app via WebSocket.
+
+```json
+{
+  "id": "uuid",
+  "aircraft": {
+    "icao24": "string",
+    "callsign": "string",
+    "origin_country": "string",
+    "last_contact": "timestamp",
+    "squawk": "string",
+    "spi": boolean,
+    "sensors": [integer]
+  },
+  "vector": {
+    "velocity": double,
+    "true_track": double,
+    "vertical_rate": double
+  },
+  "position": {
+    "longitude": double,
+    "latitude": double,
+    "geo_altitude": double,
+    "baro_altitude": double,
+    "on_ground": boolean,
+    "source": integer,
+    "time": "timestamp"
+  },
+  "last_update": "timestamp"
+}
+```
+
+### FlightDataDTO
+Used to subscribe to flight tracker data from the flight tracker producer via Kafka.
+
+```json
+{
+  "icao24": "string",
+  "callsign": "string",
+  "origin_country": "string",
+  "last_contact": long,
+  "time_position": long,
+  "longitude": double,
+  "latitude": double,
+  "baro_altitude": double,
+  "on_ground": boolean,
+  "velocity": double,
+  "true_track": double,
+  "vertical_rate": double,
+  "sensors": [integer],
+  "geo_altitude": double,
+  "squawk": "string",
+  "spi": boolean,
+  "position_source": integer
+}
+```
+
 ## Project Structure
 
 ```