HTTP headers | Retry-After

HTTP headers are used to pass additional information with HTTP request or response. HTTP Retry-After header is an HTTP response header which indicates how long to wait before making another request. Depending on different status codes, there are different use cases of the Retry-After response header.

• Status code 503: 503 is used to indicate service unavailable. Retry-After is used with 503 which tells the user how long the service is expected to be unavailable. It is used to deal with scheduled downtime.
• Status code 301: 301 is used to indicate that resource is moved permanently. Retry-After is used with 301 which tells the user about the minimum for which user should wait before issuing the redirect request.
• Status code 429: 429 id is used to indicate too many request. Retry-After is used with 429 to tells the user how long to wait before making another request.

Syntax:

Retry-After: <http-date>
Retry-After: <delay-seconds>

Directives: This header accepts two directives as mentioned above and described below:

• http-date: It indicated the date after which user should resend the request.
• delay-seconds: It is an integer value indicating the no of seconds after which user should resend the request.

Example: This example will illustrates the HTTP Retry-After header:

• Using date directive, after that date with the specified time client can retry the request.

Retry-After: Sun, 27 Oct 2019 09:45:00 GMT

• Using delay-second directive, after that specified second client can retry the request.

Retry-After: 180

Supported Browsers: The browsers compatible with HTTP Retry-After header are listed below:

• Google Chrome
• Internet Explorer
• Firefox
• Safari
• Opera