HttpRuntimeCache

HttpRuntimeCache is a class in the .NET Framework that provides an in-memory cache for ASP.NET applications. It allows developers to store frequently accessed data in memory to improve application performance by reducing the need to hit databases or perform expensive computations repeatedly. The cache is managed by the ASP.NET runtime and is associated with the application's AppDomain.

Items can be added to the HttpRuntimeCache using the Insert method, which accepts a key, the object to cache, and optionally a CacheDependency, a CacheItemPolicy, or a CacheItemRemovedCallback. The CacheDependency allows the cached item to be invalidated when an external resource changes, such as a file or another cache item. The CacheItemPolicy provides control over expiration, such as absolute or sliding expiration times. The CacheItemRemovedCallback is executed when an item is removed from the cache.

Retrieving items from the HttpRuntimeCache is done using the cache object directly as an indexer with the item's key. If the item is not found, the indexer returns null. The HttpRuntimeCache is an instance-level cache, meaning each application domain has its own independent cache. This is distinct from the HttpCache, which is an application-level cache. The HttpRuntimeCache is considered a lower-level API compared to the newer MemoryCache class introduced in .NET Framework 4, which offers more advanced features and flexibility. However, HttpRuntimeCache remains a widely used and efficient option for basic caching needs within ASP.NET.