Notification Services—Creating a Subscription Class and Subscription Event Rule

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Creating a Subscription Class and Subscription Event Rule

A subscription class with a single subscription event rule is created in the CreateSubscriptionClassMethod( ) method of Example 18-1. The code follows:

private static void CreateSubscriptionClass( )
{
  SubscriptionClass sc = 
    new SubscriptionClass(a, 
    "StockWatchSubscriptions");
  SubscriptionField sf;
  sf = new SubscriptionField(sc, 
    "DeviceName");
  sf.Type = "nvarchar(255)";
  sc.SubscriptionFields.Add(sf);
  sf = new SubscriptionField(sc, 
    "SubscriberLocale");
  sf.Type = "nvarchar(10)";
  sc.SubscriptionFields.Add(sf);
  sf = new SubscriptionField(sc, "Symbol");
  sf.Type = "nvarchar(6)";
  sc.SubscriptionFields.Add(sf);
  sf = new SubscriptionField(sc, "Price");
  sf.Type = "float";
  sc.SubscriptionFields.Add(sf);
  SubscriptionEventRule ser =
    new SubscriptionEventRule
    (sc, "StockWatchSubscriptionsEventRule");
  ser.Action = @"INSERT INTO StockWatchNotifications (" +
    "SubscriberId, DeviceName, SubscriberLocale, Symbol, Price) " +
    "SELECT s.SubscriberId, s.DeviceName, s.SubscriberLocale, " +
    "e.Symbol, e.Price " +
    "FROM StockWatchEvents e, StockWatchSubscriptions s " +
    "WHERE e.Symbol = s.Symbol";
  ser.EventClassName = "StockWatchEvents";
  sc.SubscriptionEventRules.Add(ser);
  a.SubscriptionClasses.Add(sc);
  Console.WriteLine("Added subscription class: " + sc.Name);
}

A SubscriptionEventRule object represents a rule that uses T-SQL queries to generate notifications when event batches arrive. The Action property represents the T-SQL query for the SubscriptionEventRule object. In this example, notifications are generated when the ticker symbol of an event matches the ticker symbol specified in a subscription.

The NMO classes for managing the different types of subscription rules are described in Table 18-6.

Table 18-5. NMO classes for managing subscription chronicles, classes, and fields

A SubscriptionEventRule object represents a rule that uses T-SQL queries to generate notifications when event batches arrive. The Action property represents the T-SQL query for the SubscriptionEventRule object. In this example, notifications are generated when the ticker symbol of an event matches the ticker symbol specified in a subscription.

The NMO classes for managing the different types of subscription rules are described in Table 18-6.

Table 18-6. NMO classes for managing subscription rules