PreparingEnlistment.Prepared Method

Definition

Namespace:

System.Transactions

Assembly:

System.Transactions.Local.dll

Source:

PreparingEnlistment.cs

Indicates that the transaction can be committed.

public:
 void Prepared();

public void Prepared ();

member this.Prepared : unit -> unit

Public Sub Prepared ()

Examples

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 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 the first (prepare) phase of a two phase commit, a resource manager implementing the Prepare method of the IEnlistmentNotification interface, calls this method to indicate that the transaction can be committed.

The resource manager can call the Done method at anytime before it has called this method. By doing so, the enlistment is casting a read only vote, meaning that it votes commit on the transaction but does not need to receive the final outcome.

Once this method is called by an enlistment and before it returns, it is possible that another thread or this same thread could make a call into the same enlistment method such as Rollback to perform a rollback. This can result in a deadlock situation if the resource manager implementation does not release resource locks until after this method returns.