cache

############################################## Variant 1 ##############################################
ICacheService.cs
namespace TicketingSystem.Web.Infrastructure.Caching
{
    using System;

    public interface ICacheService
    {
        T GetOrSet<T>(string cacheKey, Func<T> getItemCallback) where T : class;

        void Clear(string cacheKey);
    }
}

InMemoryCache.cs
namespace TicketingSystem.Web.Infrastructure.Caching
{
    using System;
    using System.Runtime.Caching;

    public class InMemoryCache : ICacheService
    {
        public T GetOrSet<T>(string cacheKey, Func<T> getItemCallback) where T : class
        {
            T item = MemoryCache.Default.Get(cacheKey) as T;
            if (item == null)
            {
                item = getItemCallback();
                MemoryCache.Default.Add(cacheKey, item, DateTime.Now.AddMinutes(30));
            }

            return item;
        }

        public void Clear(string cacheKey)
        {
            MemoryCache.Default.Remove(cacheKey);
        }
    }
}

############################################## Variant 2 ##############################################
ICacheService.cs
namespace Bookmarks.Web.Infrastructure.CacheService
{
    using System.Collections.Generic;

    using Bookmarks.Web.ViewModels;

    public interface ICacheService
    {
        IList<BookmarkViewModel> Bookmarks { get; }
    }
}

BaseCacheService.cs
namespace Bookmarks.Web.Infrastructure.CacheService
{
    using System.Web;

    using Antlr.Runtime.Misc;

    public class BaseCacheService
    {
        protected T Get<T>(string cacheId, Func<T> getItemcallback) where T : class
        {
            var item = HttpRuntime.Cache.Get(cacheId) as T;
            if (item == null)
            {
                item = getItemcallback();
                HttpContext.Current.Cache.Insert(cacheId, item);
                return item;
            }

            return item;
        }
    }
}

MemoryCacheService.cs
namespace Bookmarks.Web.Infrastructure.CacheService
{
    using System.Collections.Generic;
    using System.Linq;

    using AutoMapper.QueryableExtensions;

    using Bookmarks.Data;
    using Bookmarks.Web.ViewModels;

    public class MemoryCacheService : BaseCacheService, ICacheService
    {
        private readonly IBookmarksData data;

        public MemoryCacheService(IBookmarksData data)
        {
            this.data = data;
        }

        public IList<BookmarkViewModel> Bookmarks
        {
            get
            {
                return this.Get<IList<BookmarkViewModel>>("Bookmarks", () =>
                    this.data.Bookmarks
                        .All()
                        .OrderByDescending(x => x.Votes.Sum(v => v.Value))
                        .Take(6)
                        .Project()
                        .To<BookmarkViewModel>()
                        .ToList());
            }
        }
    }
}