将SqlDependency与名为Queues一起使用

Question

我有以下代码使用SqlDependency来监视我的一个数据库中的更改它工作得很好,除了每次运行它在数据库中生成自己的带有guid的队列/服务/路由:

类:

class SqlWatcher
{
    private string connectionString;
    private string sqlQueue;
    private string listenerQuery;
    private SqlDependency dependency;

    public SqlWatcher(string connectionString, string sqlQueue, string listenerQuery)
    {
        this.connectionString = connectionString;
        this.sqlQueue = sqlQueue;
        this.listenerQuery = listenerQuery;
        this.dependency = null;
    }

    public void Start()
    {
        SqlDependency.Start(connectionString);
        ListenForChanges();
    }

    public void Stop()
    {
        SqlDependency.Stop(this.connectionString);
    }

    private void ListenForChanges()
    {
        //Remove existing dependency, if necessary
        if (dependency != null)
        {
            dependency.OnChange -= onDependencyChange;
            dependency = null;
        }

        SqlConnection connection = new SqlConnection(connectionString);
        connection.Open();

        SqlCommand command = new SqlCommand(listenerQuery, connection);

        dependency = new SqlDependency(command);

        // Subscribe to the SqlDependency event.
        dependency.OnChange += new OnChangeEventHandler(onDependencyChange);

        SqlDependency.Start(connectionString);

        command.ExecuteReader();

        //Perform this action when SQL notifies of a change
        performAction();

        connection.Close();
    }

    private void onDependencyChange(Object o, SqlNotificationEventArgs args)
    {
        if ((args.Source.ToString() == "Data") || (args.Source.ToString() == "Timeout"))
        {
            Console.WriteLine(System.Environment.NewLine + "Refreshing data due to {0}", args.Source);
            ListenForChanges();
        }
        else
        {
            Console.WriteLine(System.Environment.NewLine + "Data not refreshed due to unexpected SqlNotificationEventArgs: Source={0}, Info={1}, Type={2}", args.Source, args.Info, args.Type.ToString());
        }
    }

    private void performAction()
    {
        Console.WriteLine("Performing action");
    }
}

执行:

static void Main(string[] args)
{
   string connectionString = @"<MY CONNECTION STRING>"; 
   string sqlQueue = @"NamesQueue";

   //Listener query restrictions: http://msdn.microsoft.com/en-us/library/aewzkxxh.aspx
   string listenerQuery = "SELECT Value FROM dbo.Table WHERE Name = 'Test'";

   SqlWatcher w = new SqlWatcher(connectionString, sqlQueue, listenerQuery);
   w.Start();
   Thread.Sleep(10000);
   w.Stop();
}

我不想每次都生成自己的队列/服务/路由,而是先创建它们然后告诉我的程序使用它们.

我继续在数据库上创建这些对象:

CREATE QUEUE NamesQueue;
CREATE SERVICE NamesService ON QUEUE NamesQueue;
CREATE ROUTE NamesRoute WITH SERVICE_NAME = 'NamesService', ADDRESS = 'LOCAL';

并修改了我的C#代码以使用此队列和服务:

...
SqlDependency.Start(connectionString, sqlQueue);
...
SqlDependency.Stop(this.connectionString, sqlQueue);
...
dependency = new SqlDependency(command, "service=NamesService;local database=<MY DB>", 0);
...
SqlDependency.Start(connectionString,sqlQueue);
...

进行这些代码更改会导致在运行代码时无法动态创建队列,但是我的代码不再有效,我的应用程序无法识别对我的表/查询所做的更改.

我花了好几天试图解决这个问题没有成功,任何人都可以提供任何建议吗？谢谢.

Answer 1

弄清楚了 - 错误发生在我的SQL CREATE语句中.我用的是:

CREATE SERVICE NamesService ON QUEUE NamesQueue;

但根据http://technet.microsoft.com/en-us/library/ms190332.aspx,CREATE SERVICE命令需要采用contract_name参数,以便能够允许其他对话框定位正在创建的服务.

所以,使用下面的CREATE语句修复了我的问题:

CREATE SERVICE NamesService
ON QUEUE NamesQueue
([http://schemas.microsoft.com/SQL/Notifications/PostQueryNotification]) ;