Cache Helper

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Configuration;

namespace Optevia.Portal.OPSE.Helpers.Customer
{

    public static class CacheHelper
    {
        /// <summary>
        /// Insert value into the cache using
        /// appropriate name/value pairs
        /// </summary>
        /// <typeparam name="T">Type of cached item</typeparam>
        /// <param name="o">Item to be cached</param>
        /// <param name="key">Name of item</param>
        public static void Add<T>(T o, string key)
        {
            // NOTE: Apply expiration parameters as you see fit.
            // I typically pull from configuration file.

            // In this example, I want an absolute
            // timeout so changes will always be reflected
            // at that time. Hence, the NoSlidingExpiration.
            HttpContext.Current.Cache.Insert(
                key,
                o,
                null,
                DateTime.Now.AddMinutes(Convert.ToDouble(ConfigurationManager.AppSettings["MasterTemplatePage"])),
                System.Web.Caching.Cache.NoSlidingExpiration);
        }

        /// <summary>
        /// Remove item from cache
        /// </summary>
        /// <param name="key">Name of cached item</param>
        public static void Clear(string key)
        {
            HttpContext.Current.Cache.Remove(key);
        }

        /// <summary>
        /// Check for item in cache
        /// </summary>
        /// <param name="key">Name of cached item</param>
        /// <returns></returns>
        public static bool Exists(string key)
        {
            return HttpContext.Current.Cache[key] != null;
        }

        /// <summary>
        /// Retrieve cached item
        /// </summary>
        /// <typeparam name="T">Type of cached item</typeparam>
        /// <param name="key">Name of cached item</param>
        /// <param name="value">Cached value. Default(T) if 
        /// item doesn't exist.</param>
        /// <returns>Cached item as type</returns>
        public static bool Get<T>(string key, out T value)
        {
            try
            {
                if (!Exists(key))
                {
                    value = default(T);
                    return false;
                }

                value = (T)HttpContext.Current.Cache[key];
            }
            catch
            {
                value = default(T);
                return false;
            }

            return true;
        }
    }

}

And here is a relatively standard sample usage of the library.

string key = "EmployeeList";
List<Employee> employees;

if (!CacheHelper.Get(key, out employees))
{
    employees = DataAccess.GetEmployeeList();
    CacheHelper.Add(employees, key);
    Message.Text =
        "Employees not found but retrieved and added to cache for next lookup.";
}
else
{
    Message.Text = "Employees pulled from cache.";
}