About

An HTTP conditional request is a request that contains an IF headers

Example

If-Modified-Since: Sat, 07 Feb 2015 16:44:03 GMT
If-None-Match: "e026b5aa0e4be8d990f093176b3dcb7f"

Note that you can get one or both from the usger agent (browser)

Usage

• What is a cache validation (conditional HTTP GET request) ?
• Integrity of a partial download
• Avoiding the lost update problem with optimistic locking
• Dealing with the first upload of a resource

Specification

• rfc7232, R. Fielding, J. Reschke. IETF.

Documentation / Reference

• https://developer.mozilla.org/en-US/docs/Web/HTTP/Conditional_requests