Context Sensitive Help using Client Callbacks - AJAX Style

/*
 * Cache Management Class
 * ==============================================================
 * Creator 			Ch.V.L.Mahendra
 * Created			17-Sep-2006
 * Environments		IIS 5.*, IIS 6.0, .Net Framework 2.0
 * Description 
 *
 * Responsible for managing the application cache. If cache
 * elements need updating, this class fetches information to
 * populate them from the database or XML file as applicable.
 *
 * Change Log
 * ==============================================================
 * Version	Date		Author		    Changes
 * 0.1		17-Sep-2006	Ch.V.L.Mahendra	Created
 */

using System;
using System.Web.Caching;
using System.Collections;
using System.Xml;
using ContextSensitiveHelp.Pages.Xml;

namespace ContextSensitiveHelp.Pages.Common
{
    /// <summary>
    /// Manages the application cache, and populates it if neccessary.
    /// </summary>
    public class CacheManager
    {
        #region Private Variables
        /// <summary>
        /// The cache object to hold the data.
        /// </summary>
        private Cache objApplicationCache;
        /// <summary>
        /// Variable to hold the status of the data in the Cache.
        /// </summary>
        private bool blnRefreshed;

        #endregion 

        #region Properties

        /// <summary>
        /// Value indicating whether cache has been refreshed in this instance
        /// </summary>
        public bool IsRefreshed
        {
            get
            {
                return blnRefreshed;
            }
            set
            {
                blnRefreshed = value;
            }
        }

        #endregion 

        #region Private Methods
             
        #region Method to Refresh the Messages Xml

        /// <summary>
        /// Refreshes the application error messages into the application cache.
        /// </summary>
        private void RefreshMessages()
        {
            /* load the XML error file into memory */
            XmlDocument objDocument = new XmlDocument();
            objDocument.Load(XmlMessage.XmlFile);
            objApplicationCache.Insert("appMessages", objDocument, new CacheDependency(XmlMessage.XmlFile));
            this.IsRefreshed = true;
        }

        #endregion 

        #endregion

        #region Public Methods

        #region Constructor Logic

        /// <summary>
        /// Constructor for the cache manager, checks that the
        /// lookup table has been cached by the application.
        /// </summary>
        /// <param name="objCache">The application's cache object</param>
        public CacheManager(Cache objCache)
        {
            objApplicationCache = objCache;
            this.IsRefreshed = false;
        }

        #endregion 
        
                  
        #region Method to load the Messages Xml

        /// <summary>
        /// Load the application help messages from the cache
        /// </summary>
        public void LoadMessages()
        {
            if (objApplicationCache["appMessages"] == null)
                RefreshMessages();

            XmlMessage.Xml = (XmlDocument)objApplicationCache["appMessages"];
        }

        #endregion 
      
        #endregion

    }
}