JSON Response headers

Question

The following headers seem to be recommended using when outputing JSON:

header('Cache-Control: no-cache, must-revalidate');
header('Expires: Mon, 26 Jul 1997 05:00:00 GMT');
header('Content-type: application/json');

What is the purpose of the Expires header when Cache-control is set to no-cache, must-revalidate?

blue · Accepted Answer · 2014-04-09 12:46:02Z

2

This resolves some browser and caching proxies issues.

It seems like there are some of these that do not understand some headers and/or are configured not to, so it is just a workaround trying to be compatible with a little more of the end users' browser and caching proxies in the middle.

answered Apr 9, 2014 at 12:46

blue

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2 Comments

seberik Over a year ago

Alright, thanks! Is there any reason for doing this: header('Cache-Control: no-cache, must-revalidate'); header('Expires: '.date('r', time()+(86400*365)); (ellislab.com/forums/viewthread/190001)?

blue Over a year ago

@seberik - my guess is that the + /plus/ is a typo and was supposed to be a - /minus/.

Ashish Rathore · Accepted Answer · 2014-04-09 12:48:18Z

0

The first two headers prevent the browser from caching the response (a problem with IE and GET requests) and the third sets the correct MIME type for JSON.

answered Apr 9, 2014 at 12:48

Ashish Rathore

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