IEnlistmentNotification Interface
Definition
Important
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Describes an interface that a resource manager should implement to provide two phase commit notification callbacks for the transaction manager upon enlisting for participation.
public interface class IEnlistmentNotificationpublic interface IEnlistmentNotificationtype IEnlistmentNotification = interfacePublic Interface IEnlistmentNotification- Derived
Examples
The following example shows an implementation of this interface, as well as enlisting the object as a participant in a transaction using the EnlistVolatile method.
static void Main(string[] args)
{
try
{
using (TransactionScope scope = new TransactionScope())
{
//Create an enlistment object
myEnlistmentClass myElistment = new myEnlistmentClass();
//Enlist on the current transaction with the enlistment object
Transaction.Current.EnlistVolatile(myElistment, EnlistmentOptions.None);
//Perform transactional work here.
//Call complete on the TransactionScope based on console input
ConsoleKeyInfo c;
while(true)
{
Console.Write("Complete the transaction scope? [Y|N] ");
c = Console.ReadKey();
Console.WriteLine();
if ((c.KeyChar == 'Y') || (c.KeyChar == 'y'))
{
scope.Complete();
break;
}
else if ((c.KeyChar == 'N') || (c.KeyChar == 'n'))
{
break;
}
}
}
}
catch (System.Transactions.TransactionException ex)
{
Console.WriteLine(ex);
}
catch
{
Console.WriteLine("Cannot complete transaction");
throw;
}
}
class myEnlistmentClass : IEnlistmentNotification
{
public void Prepare(PreparingEnlistment preparingEnlistment)
{
Console.WriteLine("Prepare notification received");
//Perform transactional work
//If work finished correctly, reply prepared
preparingEnlistment.Prepared();
// otherwise, do a ForceRollback
preparingEnlistment.ForceRollback();
}
public void Commit(Enlistment enlistment)
{
Console.WriteLine("Commit notification received");
//Do any work necessary when commit notification is received
//Declare done on the enlistment
enlistment.Done();
}
public void Rollback(Enlistment enlistment)
{
Console.WriteLine("Rollback notification received");
//Do any work necessary when rollback notification is received
//Declare done on the enlistment
enlistment.Done();
}
public void InDoubt(Enlistment enlistment)
{
Console.WriteLine("In doubt notification received");
//Do any work necessary when indout notification is received
//Declare done on the enlistment
enlistment.Done();
}
}
Public Shared Sub Main()
Try
Using scope As TransactionScope = New TransactionScope()
'Create an enlistment object
Dim myEnlistmentClass As New EnlistmentClass
'Enlist on the current transaction with the enlistment object
Transaction.Current.EnlistVolatile(myEnlistmentClass, EnlistmentOptions.None)
'Perform transactional work here.
'Call complete on the TransactionScope based on console input
Dim c As ConsoleKeyInfo
While (True)
Console.Write("Complete the transaction scope? [Y|N] ")
c = Console.ReadKey()
Console.WriteLine()
If (c.KeyChar = "Y") Or (c.KeyChar = "y") Then
scope.Complete()
Exit While
ElseIf ((c.KeyChar = "N") Or (c.KeyChar = "n")) Then
Exit While
End If
End While
End Using
Catch ex As TransactionException
Console.WriteLine(ex)
Catch
Console.WriteLine("Cannot complete transaction")
Throw
End Try
End Sub
End Class
Public Class EnlistmentClass
Implements IEnlistmentNotification
Public Sub Prepare(ByVal myPreparingEnlistment As PreparingEnlistment) Implements System.Transactions.IEnlistmentNotification.Prepare
Console.WriteLine("Prepare notification received")
'Perform transactional work
'If work finished correctly, reply with prepared
myPreparingEnlistment.Prepared()
End Sub
Public Sub Commit(ByVal myEnlistment As Enlistment) Implements System.Transactions.IEnlistmentNotification.Commit
Console.WriteLine("Commit notification received")
'Do any work necessary when commit notification is received
'Declare done on the enlistment
myEnlistment.Done()
End Sub
Public Sub Rollback(ByVal myEnlistment As Enlistment) Implements System.Transactions.IEnlistmentNotification.Rollback
Console.WriteLine("Rollback notification received")
'Do any work necessary when rollback notification is received
'Declare done on the enlistment
myEnlistment.Done()
End Sub
Public Sub InDoubt(ByVal myEnlistment As Enlistment) Implements System.Transactions.IEnlistmentNotification.InDoubt
Console.WriteLine("In doubt notification received")
'Do any work necessary when indout notification is received
'Declare done on the enlistment
myEnlistment.Done()
End Sub
End Class
Remarks
In order for a resource manager to participate in a transaction, it must enlist in the transaction through the transaction manager. The Transaction class defines a set of methods whose names begin with Enlist that provide this functionality. The different Enlist methods correspond to the different types of enlistment that a resource manager may have.
This class describes an interface that a resource manager should implement to provide two phase commit notification callbacks for the transaction manager upon enlisting for participation. For each resource manager's implementation of the IEnlistmentNotification interface, you should enlist it using the EnlistVolatile method or the EnlistDurable method of the Transaction class, depending on whether your resource is volatile or durable. For more information on enlistment and 2PC, see Enlisting Resources as Participants in a Transaction and Committing a Transaction in Single-Phase and Multi-Phase respectively.
The transaction manager notifies the enlisted object at different phases of the Two Phase Commit Protocol by the following methods.
| Method | Description |
|---|---|
| Prepare | This method of an enlisted object is used as a callback by the Transaction Manager during the first phase of a transaction, when the transaction manager asks participants whether they can commit the transaction. |
| Commit | This method of an enlisted object is used as a callback by the Transaction Manager during the second phase of a transaction if the transaction is committed. |
| Rollback | This method of an enlisted object is used as a callback by the Transaction Manager during the second phase of a transaction if the transaction is aborted (that is, rolled back). |
| InDoubt | This method of an enlisted object is used as a callback by the Transaction Manager during the second phase of a transaction if the transaction is in doubt. |
Note
You should be aware that notifications might not be sent sequentially, or in a particular order.
Methods
| Commit(Enlistment) |
Notifies an enlisted object that a transaction is being committed. |
| InDoubt(Enlistment) |
Notifies an enlisted object that the status of a transaction is in doubt. |
| Prepare(PreparingEnlistment) |
Notifies an enlisted object that a transaction is being prepared for commitment. |
| Rollback(Enlistment) |
Notifies an enlisted object that a transaction is being rolled back (aborted). |
