Windows Server Appfabric provider for asp.net output caching

Question

Does asp.net output cache provider exist for Windows Server AppFabric 1.0?

Answer 1

No. But because output caching is pluggable in ASP.NET 4.0 (using the provider model), you can write your own.

To create a new output cache provider, you'll need to inherit from System.Web.Caching.OutputCacheProvider, you'll need to reference System.Web and System.Configuration.

Then it's largely a case of overriding the four methods from the base provider, Add, Get, Remove and Set.

As your site is probably going to getting quite a few hits, you'll definitely want to use a Singleton for the DataCacheFactory, this code uses Jon Skeet's singleton pattern (assuming I've understood it correctly).

using System;
using System.Web.Caching;
using Microsoft.ApplicationServer.Caching;

namespace AppFabricOutputCache
{
public sealed class AppFabricOutputCacheProvider : OutputCacheProvider
{
    private static readonly AppFabricOutputCacheProvider instance = new AppFabricOutputCacheProvider();
    private DataCacheFactory factory;
    private DataCache cache;

    static AppFabricOutputCacheProvider()
    { }

    private AppFabricOutputCacheProvider()
    {
        // Constructor - new up the factory and get a reference to the cache based 
        // on a setting in web.config
        factory = new DataCacheFactory();
        cache = factory.GetCache(System.Web.Configuration.WebConfigurationManager.AppSettings["OutputCacheName"]);
    }

    public static AppFabricOutputCacheProvider Instance
    {
        get { return instance; }
    }

    public override object Add(string key, object entry, DateTime utcExpiry)
    {
        // Add an object into the cache. 
        // Slight disparity here in that we're passed an absolute expiry but AppFabric wants
        // a TimeSpan. Subtract Now from the expiry we get passed to create the TimeSpan
        cache.Add(key, entry, utcExpiry - DateTime.UtcNow);
    }

    public override object Get(string key)
    {
        return cache.Get(key);
    }

    public override void Remove(string key)
    {
        cache.Remove(key);
    }

    public override void Set(string key, object entry, DateTime utcExpiry)
    {
        // Set here means 'add it if it doesn't exist, update it if it does'
        // We can do this by using the AppFabric Put method
        cache.Put(key, entry, utcExpiry - DateTime.UtcNow);
    }
}
}

Once you've got this written, you need to configure your application to use it in your web.config:

<system.web>
    <caching>
        <outputCache defaultProvider="AppFabricOutputCache">
            <providers>
                <add name="AppFabricOutputCache" type="AppFabricOutputCache, AppFabricOutputCacheProvider" />
            </providers>
        </outputCache>
     </caching>
</system.web>

MSDN: OutputCacheProvider
ScottGu's blog on creating OutputCacheProviders