Messages that were sent via REST and Kafka — what did they look like? JSON, XML?

In modern messaging systems, messages transmitted via REST and Kafka are most often represented in JSON format due to its simplicity and readability. JSON is well-suited for data exchange between services and clients.

However, in some cases, XML may be used, especially if the system inherits old standards or requires a more strict data schema.

Example of a JSON message for REST or Kafka:

{
  "userId": 123,
  "action": "login",
  "timestamp": "2024-06-01T12:00:00Z"
}

Thus, the choice of format depends on the project requirements, but JSON is the most common option.