How can you control the expiration and invalidation of client-side cached data?
How can you control the expiration and invalidation of client-side cached data?
Ask by Revati S Misra
Updated 25 May 2023
Various mechanisms and techniques can be used to control expiration and invalidation of client-side cached data. Here are some commonly used approaches:
The server can include her Cache-Control header in the response to instruct the client how to cache the data. The headers include "max-age" to specify the maximum time that data is considered fresh, "no-cache" to force revalidation by the server before using cached data, and "no Specify a directive such as -store. .
An ETag is an identifier that the server assigns to a specific version of a resource. The server can include her ETag in the response header and the client can send her ETag back on subsequent requests using the "If-None-Match" header. If the resource has not changed (indicated by a matching ETag), the server responds with a 304 status code, indicating that the client can use its cached copy.
The server MAY include a "Last-Modified" header in the response that indicates the timestamp of when the resource was last modified. The client can save this timestamp and send it back to the server in subsequent requests using the "If-Modified-Since" header. If the resource has not changed since that timestamp, the server will respond with his 304 status code, indicating that the client can use its cached copy.
Include the version number or unique identifier in the resource URL. When a resource is updated, its URL changes so clients request the latest version instead of relying on a cached copy.
Modify the resource URL by adding a query parameter or version number. This technique ensures that the client gets the new version of the resource because the URL is different from the cached URL.
Provide an API or mechanism for the server to explicitly notify the client to invalidate cached data. This can be accomplished through custom cache-busting headers, webhooks, or other communication methods.
It is important to note that controlling client-side caching requires coordination between the server and client. The server MUST provide appropriate cache-related headers, and the client MUST interpret these headers correctly in response. Additionally, different browsers and caching systems may have their own caching behavior and configuration options. Therefore, it is important to consider the specific environment in which the application will be deployed.