IEnlistmentNotification Interface

Definition

Namespace:

System.Transactions

Assemblies:

netstandard.dll, System.Transactions.Local.dll

Describes an interface that a resource manager should implement to provide two phase commit notification callbacks for the transaction manager upon enlisting for participation.

C#

public interface IEnlistmentNotification

Derived

System.Transactions.ISinglePhaseNotification

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.

C#

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();
    }
}

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.

Märkus

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).

Applies to

See also

• ISinglePhaseNotification
• Enlisting Resources as Participants in a Transaction
• Committing a Transaction in Single-Phase and Multi-Phase