What did you do with invalid messages after manual processing? How did it look technically?

After manual processing of invalid messages, the following approach was usually applied:

1. Logging and analysis: messages were stored in a separate repository (for example, in a database or files) to understand the cause of the error.
2. Correction: errors in the data were corrected manually or with scripts.
3. Resending: corrected messages were placed back into the queue or processing system for reprocessing.

Technically, it looked like this:

• The message processing system had a separate channel or queue for invalid messages (dead-letter queue).
• After manual review and correction, messages were sent back to the main queue via API or CLI.

An example in Go (simplified):

func reprocessMessage(msg Message) error {
    if err := validate(msg); err != nil {
        return err
    }
    // Send the message back to the queue
    return messageQueue.Publish(msg)
}

Thus, data quality control was ensured and reprocessing was possible without data loss.