Automating Windows Applications Using Azure AppFabric Service Bus

using System;
using System.Collections.Generic;
using System.Text;
using SvcHost;

namespace NotepadHandlerNET
{
    /// <summary>
    /// Class NotificationBase serves as base for all notification classes.
    /// </summary>
    public class NotificationBase
    {
        #region NotifAddressTable Helper Class
        /// <summary>
        /// Class NotifAddressTable contains all subscribers (clients) accessed by their URIs.
        /// </summary>
        public class NotifAddressTable : Dictionary<string, INotification>
        {
        }
        #endregion

        #region Variables
        protected static NotifAddressTable nat = null;
        protected Exception e = null;
        #endregion

        #region Static Ctor
        /// <summary>
        /// Static ctor.
        /// </summary>
        static NotificationBase()
        {
            nat = new NotifAddressTable();
        }
        #endregion

        #region Methods
        /// <summary>
        /// Method returns notification proxy for a given endpoint URI.
        /// </summary>
        private INotification FindNotificationClient(string endpointAddressUriNotification)
        {
            INotification notifProxy = null;
            if (null != endpointAddressUriNotification)
            {
                try
                {
                    notifProxy = nat[endpointAddressUriNotification.ToLower()];
                }
                catch //(Exception e)
                {
                }
            }

            return notifProxy;
        }

        /// <summary>
        /// Method returns notification proxy of a given endpoint URI.
        /// </summary>
        protected void RemoveNotificationClient(INotification notifProxy)
        {
            lock (typeof(NotifAddressTable))
            {
                string uriToRemove = null;
                foreach (string uri in nat.Keys)
                    if (nat[uri] == notifProxy)
                        uriToRemove = uri;

                nat.Remove(uriToRemove);        
            }
        }

        /// <summary>
        /// Wrapper method around notification call.
        /// </summary>
        protected object Notify(INotification notifProxy, string sender, string eventName, object data)
        {
            object ret = null;
            if (null != notifProxy)
            {
                try
                {
                    ret = notifProxy.Notify(sender, eventName, data);
                }
                catch //(Exception e)
                {
                    RemoveNotificationClient(notifProxy);
                }
            }

            return ret;
        }

        /// <summary>
        /// Method provides (either finds or creates) notification proxy. Synchronization is required.
        /// </summary>
        protected INotification GetNotificationClient(string endpointAddressUriNotification)
        {
            INotification notifProxy = null;
            string uri = endpointAddressUriNotification.ToLower();

            lock (typeof(NotifAddressTable))
            {
                notifProxy = FindNotificationClient(endpointAddressUriNotification);
                if (null == notifProxy)
                {
                    try
                    {
                        notifProxy = Client.ConnectTo<INotification>(endpointAddressUriNotification);
                        if (null != notifProxy)
                            nat.Add(uri, notifProxy);
                    }
                    catch (Exception e)
                    {
                        this.e = e;
                    }
                }
            }

            return notifProxy;
        }

        /// <summary>
        /// Method returns a list of all notification proxies. Synchronization is required.
        /// </summary>
        protected List<INotification> GetAllNotificationSubscribers()
        {
            List<INotification> listProxy = new List<INotification>();

            lock (typeof(NotifAddressTable))
            {
                foreach (string uri in nat.Keys)
                    listProxy.Add(FindNotificationClient(uri));
            }

            return listProxy;
        }
        #endregion
    }
}