Une classe d’expiration basée sur SqlDependency pour le cache d’Enterprise Library

Une classe d’expiration basée sur SqlDependency pour le cache d’Enterprise Library

    ///<summary>

    ///     This class tracks a SQL Server dependency.

    ///</summary>

    [Serializable]

    [ComVisible(false)]

    public class SqlServerDependency :ICacheItemExpiration

    {

        private bool isExpired;

        ///<summary>

        /// Get expiration state

        ///</summary>

        public bool IsExpired

        {

            get { return isExpired; }

        }

        ///<summary>

        /// Constructor with one argument.

        ///</summary>

        ///<param name="command"></param>

        public SqlServerDependency(SqlCommand command)

        {

            SqlDependency.Stop(command.Connection.ConnectionString);

            SqlDependency.Start(command.Connection.ConnectionString);

            command.Notification = null;

            SqlDependency sqlDependency = new SqlDependency(command);

            sqlDependency.OnChange += new OnChangeEventHandler(OnChanged);

            if (command.Connection.State == ConnectionState.Closed)

                command.Connection.Open();

            command.ExecuteReader(CommandBehavior.CloseConnection);

        }

        void OnChanged(object sender, SqlNotificationEventArgs e)

        {

            SqlDependency sqlDependency = sender as SqlDependency;

            sqlDependency.OnChange -= OnChanged;

            isExpired = true;

        }

        ///<summary>

        /// Specifies if the item has expired or not.

        ///</summary>

        ///<returns>Returns true if the item has expired, otherwise false.</returns>

        public bool HasExpired()

        {

            return isExpired;

        }

        ///<summary>

        /// Notifies that the item was recently used.

        ///</summary>

        public void Notify()

        {

        }

        ///<summary>

        /// Not used

        ///</summary>

        ///<param name="owningCacheItem">Not used</param>

        public void Initialize(CacheItem owningCacheItem)

        {

        }

    }

Exemple d’utilisation

CacheManager cacheManager = CacheFactory.GetCacheManager();

        private void button1_Click(object sender, EventArgs e)

        {

            DataSet dataSet=null;

            if (cacheManager.Contains("AllContacts"))

            {

                dataSet = (DataSet)cacheManager["AllContacts"];

                label1.Text = "from cache";

            }

            else

            {

                Database db = DatabaseFactory.CreateDatabase();

                DbCommand command = db.GetStoredProcCommand("dbo.GetAllContacts");

                dataSet = db.ExecuteDataSet(command);

                //

                SqlServerDependency dependency = new SqlServerDependency(

                    new SqlCommand("select ContactID,ContactName,ContactFirstName,ContactAge from dbo.Contact",

                    new SqlConnection((ConfigurationManager.GetSection("connectionStrings") as ConnectionStringsSection).ConnectionStrings[1].ConnectionString)

                        )

                    );

                cacheManager.Add("AllContacts", dataSet, CacheItemPriority.Normal, null, new ICacheItemExpiration[] { dependency });

                label1.Text = "from database";

            }

            dataGridView1.DataSource = dataSet.Tables[0];

        }

La classe SqlServerDependency ici