It should always be less than a year in the future. It is pretty straightforward: we just indicate a date in the future when the response expires. A typical example of usage is: Expires: Sun, 23:02:37 GMT It is not as powerful as Cache-Control, but it gives us some degree of control for old clients. In that version we have the Expires directive. Of course there are more directives available but most use cases are covered with just the five mentioned above.īefore diving into validation territory, I want to mention the alternative for HTTP 1.0.
If we wanted to avoid all sorts of caching, we could have used no-store instead. no-cache: the response can be cached only if the ETag header is present and must be validated before using it again (more on that in the next section).In the next section we will dig further into validation. In this case is 0, meaning that the client must validate the response before using it again. max-age: max amount of time in seconds that cached responses are considered fresh and can be used without validation.If we were dealing with public content we should have used public and let intermediate caches store the response. private: this directive indicates that the response is intended for a single user and as a result must not be cached by shared caches (like caching proxies) and can only be cached by a private non shared cache (like the one in your browser).Let’s break the header value down into pieces (cache directives): When we use such a header in a response, we are instructing the client to cache the response only in the browser (not in intermediate caches) and to validate it for any further use of the same resource.
The header used for cache control in http 1.1+ is Cache-Control and a classic example looks like this : Cache-Control: private, max-age=0, no-cache It is performed using two different headers: one to set the caching policies and one for validation support. Taking control of data cachingĬache control in HTTP is managed using headers. If you are interested in all the details, the RFC is the best place to look into. This story is just an introduction to the topic. HTTP has provided support for cache control since the HTTP 1.0 days (1996), but a lot of developers still oversee this important topic and happily accept whatever defaults happen to be in place for their browser/server combinations.
Unknown quality and throughput is exactly what we can expect of the average connection to the internet so we should try to maximize the usage of the cache for our communications using the HTTP protocol. Caching data always pays off, but it is specially important when the connection between the parties interchanging information is of unknown quality and varying bandwidth.
React http private cache software#
Caching data is the most basic and important optimization you can apply to any piece of software that relies on sending data back and forth between different computers.
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