Cache invalidation
Cache invalidation is a process in a computer system whereby entries in a cache are replaced or removed. It can be done explicitly, as part of a cache coherence protocol. In such a case, a processor changes a memory location and then invalidates the cached values of that memory location across the rest of the computer system. Explicit invalidation Cache invalidation can be used to push new content to a client. This method functions as an alternative to other methods of displaying new content to connected clients. Invalidation is carried out by changing the application data, which in turn marks the information received by the client as out-of-date. After the cache is invalidated, if the client requests the cache, they are delivered a new version. Methods There are three specific methods to invalidate a cache, but not all caching proxies support these methods. Purge Removes content from caching proxy immediately. When the client requests the data again, it is fetched from the application and stored in the caching proxy. This method removes all variants of the cached content. Refresh Fetches requested content from the application, even if cached content is available. The content previously stored in the cache is replaced