This constructor creates an instance of the OracleDependency class and binds it to the specified OracleCommand instance, while specifying whether or not a registration is to be removed upon notification, the timeout value of the notification registration, and the persistence of the notification.

Declaration

// C#
public OracleDependency (OracleCommand cmd, bool isNotifiedOnce, long timeout,
  bool isPersistent)

Parameters

• cmd

  The command associated with the Continuous Query Notification request.

• isNotifiedOnce

  An indicator that specifies whether or not the registration is removed automatically once the notification occurs.

• timeout

  The amount of time, in seconds, that the registration stays active. When timeout is set to 0, the registration never expires. The valid values for timeout are between 0 and 4294967295.

• isPersistent

  Indicates whether or not the invalidation message should be queued persistently in the database before delivery. If the isPersistent parameter is set to True, the message is queued persistently in the database and cannot be lost upon database failures or shutdowns. If the isPersistent property is set to False, the message is stored in an in-memory queue before delivery and might be lost.

  Database performance is faster if the message is stored in an in-memory queue rather than in the database queue.

Exceptions

ArgumentNullException - The cmd parameter is null.

ArgumentOutOfRangeException - The specified timeout is invalid.

InvalidOperationException - The specified OracleCommand instance already contains a notification request.

Remarks

When this OracleDependency constructor binds the OracleCommand instance to an OracleDependency instance, it causes the creation of an OracleNotificationRequest instance and then sets that OracleNotificationRequest instance to the OracleCommand.Notification property.

The Continuous Query Notification is registered with the database, when the command is executed. Any of the command execution methods (for example, ExecuteNonQuery, ExecuteReader, and so on) will register the notification request. An OracleDependency may be bound to more than one OracleCommand. When one of these OracleCommand object statements is executed, the statement is registered with the associated OracleCommand. Although the registration happens on each OracleCommand separately, one OracleDependency can be responsible for detecting and sending notifications that occur for all OracleCommand objects that the OracleDependency is associated with. The OnChangeEventArgs that is passed to the application for the OnChange event provides information on what has changed in the database.

The OracleNotificationRequest instance that is created by this constructor has the following default property values:

• IsNotifiedOnce is set to the specified value.

• Timeout is set to the specified value.

• IsPersistent is set to the specified value.