Java 9 Programming By Example

Status codes

The response starts with the status code. These codes are also defined and there are a limited number of codes usable in a response. The most important is 200, which says all is OK; the response contains what the request wanted. The codes are always in the range of 100 to 599, contain three digits, and are grouped by the first digit.

• 1xx: These codes are information codes. They are rarely used but can be very important in some cases. For example, 100 means continue. A server can send this code when it gets a POST request and the server wants to signal the client to send the body of the request because it can process it. Using this code, and the client waiting for this code, may save a lot of bandwidth if properly implemented ...