ASP.NET 4.0 Cache Extensibility Stefan SchackowProgram Manager Microsoft CorporationPC41

What's the current state?Why is it changing?How are we changing it?.NET Framework Caching

A great in-memory object cache in ASP.NETLots of configurable "knobs"Expiration policiesAutomatic scavenging behaviorBefore and after removal callbacksExtensible cache dependenciesOutput caching of ASP.NET contentPages Fragment caching of ASP.NET controlsDonut caching with cache substitutionOutput caching of arbitrary HTTP responseCurrent Cache Functionality

In-memory cache has various constraintsObject cache API exists in System.WebAwkward to use object cache outside of ASP.NETCommon question: Why do I have to include System.Web.dll in my WPF/Winforms project?Not available in 3.5 SP1 Client SKUCaching is a "black box"Where can vendors and developers plugin?Memcached, Velocity, ScaleOut, etc… have no clean integration point available to themOutput caching is completely opaqueEach custom caching solution is a completely different API for developers to learnWhy Make Changes?

Proposed New Cache FunctionalityA new, extensible, object cache API in its own namespace and assemblySupports both client and server applicationsCan be made available on both desktop and client SKUsA factored version of the ASP.NET cache engineExtensible ASP.NET output cachingConsistent APIs for programming againstDisk-based output cachesCustom object cachesCloud-based object cachesDistributed object caches

New 4.0 Cache FunctionalityNamespace System.Caching{In-memoryDisk basedCacheWindows AzureCacheProviderDistributed}

New 4.0 Cache FunctionalityNamespace System.Caching{CacheItemPolicy(expirations, priority, callbacks)CacheItemCacheCacheItemCacheItemCacheDependency(Sql, Key-based, File)}

Object Cachingdemo

New 4.0 Output Cache FunctionalityNamespace System.Web.Caching{Default.aspxIn-memoryDisk basedFoo.ascxWindows AzureOutputCacheProviderDistributed}

Output Cachingdemo

Core Versus Optional APIsCache API is a "union" of common functionalityNot all cache providers need to implement all featuresCore functionality for all providersRepresented on CacheProvider base typeStoring and retrieving a key-value pairBasic Add/Get/Set/Contains/Remove methodsNamed cache partitionsProviders specialize by deriving fromInMemoryCacheProviderOutOfProcessCacheProvider

InMemoryCacheProviderRepresents a provider running exclusively in a single app-domainCount of items in cacheSliding expirationsDistributed caches usually can't synchronize sliding expiration values across multiple serversCache dependencies (derivations of CacheDependency)Distributed caches may have no concept of dependenciesItem removal callbacks (before and after removal)Distributed caches may not be able to call back to anything

OutOfProcessCacheProviderRepresents a provider that stores data outside of an app-domainVersion-based updates (CacheItem.Version)Useful for caches that support optimistic concurrencyLock-based updates (CacheItem.LockHandle)If a cache supports pessimistic concurrencyGet multiple itemsSaves multiple round-trips on fetchesQuery-tag metadata (CacheItem.QueryTags)Retrieving multiple cache items based on string tags

"Velocity" Integration"Velocity" – codename for distributed cache created by the Sql Server teamPlanned "Velocity" integration pointsOutOfProcessCacheProvider implementation for object cachingSessionStateStoreProviderBase implementation for ASP.NET session stateSidenote: Updates to session state API are planned in 4.0 to allow for more granular sets and gets.OutputCacheProvider implementation for ASP.NET output caching

Checking cache capabilitiesdemo

Migrating From Existing APIsSystem.Web.Caching.CacheCurrent plan is that it stays un-changedMight enable "opting-in" to using an object cache providerRequires developing a “shim” that can re-route calls to the new object cache provider layerCurrently the “shim” is only in the “idea phase”ASP.NET output cachingBoth page and control caching can opt-in to using custom providersBy default both types of output caching continue to use ASP.NET’s in-memory cache

Migrating From Existing APIsASP.NET control output caching<@OutputCacheoutputCacheProvider="…" />ASP.NET page output cachingProgrammatically choose different providers Override a new method on HttpApplicationHttpApplication.GetOutputCacheProviderNameCustom page output caching supports:Absolute expirationsFile-based dependencies onlyValidation and substitution callbacks must be static

Migrating From Existing APIs

Summary4.0 Caching is all about extensibility!Both object caching and ASP.NET output caching will be pluggableNew object cache APIs available for both client and full versions of .NET Framework

Related ContentBreakout Sessions/Chalk TalksPC21 – ASP.NET MVCPC30 – ASP.NET Dynamic DataPC31 – ASP.NET and JqueryPC32 – ASP.NET Ajax FuturesPC33 – Microsoft Visual Studio: Easing ASP.NET WebDevPC41 – ASP.NET Cache ExtensibilityTL48 – Microsoft Visual Studio: Web Development FuturesES15 – Deploying Web Applications with Microsoft Internet Information Services 7.0 and the Web Deployment Tool

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