Generic caching mechanism which makes sliding expiration easy.

Cache.cs

using System;
using System.Collections.Generic;
using System.Runtime.Caching;

namespace CacheServices
{
    public class Cache
    {
        protected MemoryCache _cache = new MemoryCache("general");

        public static CacheItemPolicy DefaultPolicy { get; set; }

        public static readonly Dictionary<string, CacheItemPolicy> Terms = new Dictionary<string, CacheItemPolicy>()
        {
            {"Short", new CacheItemPolicy {SlidingExpiration = new TimeSpan(0, 0, 30)}},
            {"Medium", new CacheItemPolicy {SlidingExpiration = new TimeSpan(0, 5, 0)}},
            {"Long", new CacheItemPolicy {SlidingExpiration = new TimeSpan(1, 0, 0)}},
            {"Always", new CacheItemPolicy {AbsoluteExpiration = DateTimeOffset.MaxValue}}
        };

        static Cache()
        {
            DefaultPolicy = Terms["Short"];
        }

        public object this[string key]
        {
            get { return Get(key); }
            set { Add(key, value, DefaultPolicy); }
        }

        public void Add(string key, object item, CacheItemPolicy term)
        {
            if (item == null)
                Remove(key);
            else
            {
                _cache.Remove(key);
                _cache.Add(key, item, term);
            }
        }

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

        public object Remove(string key)
        {
            return _cache.Remove(key);
        }
    }
}