Self-descriptive messages

This constraint states that each message should be able to be processed based on information contained in itself. That means, every message passed between the server and client should be stateless be independent of other messages. One message doesn't have an impact on other messages. So, it doesn't matter if two messages are passed in some particular order or not, as they are independent. The request in a message is enough to get a response and that response has all that needs to be conveyed.