Export (0) Print
Expand All

TransactionScope.Dispose Method

Note: This method is new in the .NET Framework version 2.0.

Ends the transaction scope.

Namespace: System.Transactions
Assembly: System.Transactions (in system.transactions.dll)

public void Dispose ()
public final void Dispose ()
public final function Dispose ()

Calling this method marks the end of the transaction scope. If the TransactionScope object created the transaction and Complete was called on the scope, the TransactionScope object attempts to commit the transaction when this method is called.

The use of the C# using construction ensures that this method is called even if an exception occurs. Exceptions that occur after calling this method may not affect the transaction. This method also restores the ambient transaction to it original state. A TransactionAbortedException is thrown if the transaction is not actually committed.

This method is synchronous and blocks until the transaction has been committed or aborted. Because of this, you should be extremely careful when using this method in a Windows Form (WinForm) application, or a deadlock can occur. If you call this method inside one WinForm Control event (for example, clicking a button), and use the synchronous Invoke method to direct the control to perform some UI tasks (for example, changing colors) in the middle of processing the transaction, a deadlock will happen. This is because the Invoke method is synchronous and blocks the worker thread until the UI thread finishes its job. However, in our scenario, the UI thread is also waiting for the worker thread to commit the transaction. The result is that none is able to proceed and the scope waits indefinitely for the Commit to finish. You should use BeginInvoke rather than Invoke wherever possible, because it is asynchronous and thus less prone to deadlock.

For more information on how this method is used, see the Implementing an Implicit Transaction using Transaction Scope topic.

The following example demonstrates how to use the TransactionScope class to define a block of code to participate in a transaction.

// This function takes arguments for 2 connection strings and commands to create a transaction 
// involving two SQL Servers. It returns a value > 0 if the transaction is committed, 0 if the 
// transaction is rolled back. To test this code, you can connect to two different databases 
// on the same server by altering the connection string, or to another RDBMS such as Oracle 
// by altering the code in the connection2 code block.
static public int CreateTransactionScope(
    string connectString1, string connectString2,
    string commandText1, string commandText2)
{
    // Initialize the return value to zero and create a StringWriter to display results.
    int returnValue = 0;
    System.IO.StringWriter writer = new System.IO.StringWriter();

    // Create the TransactionScope to execute the commands, guaranteeing
    // that both commands can commit or roll back as a single unit of work.
    using (TransactionScope scope = new TransactionScope())
    {
        using (SqlConnection connection1 = new SqlConnection(connectString1))
        {
            try
            {
                // Opening the connection automatically enlists it in the 
                // TransactionScope as a lightweight transaction.
                connection1.Open();

                // Create the SqlCommand object and execute the first command.
                SqlCommand command1 = new SqlCommand(commandText1, connection1);
                returnValue = command1.ExecuteNonQuery();
                writer.WriteLine("Rows to be affected by command1: {0}", returnValue);

                // If you get here, this means that command1 succeeded. By nesting
                // the using block for connection2 inside that of connection1, you
                // conserve server and network resources as connection2 is opened
                // only when there is a chance that the transaction can commit.   
                using (SqlConnection connection2 = new SqlConnection(connectString2))
                    try
                    {
                        // The transaction is escalated to a full distributed
                        // transaction when connection2 is opened.
                        connection2.Open();

                        // Execute the second command in the second database.
                        returnValue = 0;
                        SqlCommand command2 = new SqlCommand(commandText2, connection2);
                        returnValue = command2.ExecuteNonQuery();
                        writer.WriteLine("Rows to be affected by command2: {0}", returnValue);
                    }
                    catch (Exception ex)
                    {
                        // Display information that command2 failed.
                        writer.WriteLine("returnValue for command2: {0}", returnValue);
                        writer.WriteLine("Exception Message2: {0}", ex.Message);
                    }
            }
            catch (Exception ex)
            {
                // Display information that command1 failed.
                writer.WriteLine("returnValue for command1: {0}", returnValue);
                writer.WriteLine("Exception Message1: {0}", ex.Message);
            }
        }

        // The Complete method commits the transaction. If an exception has been thrown,
        // Complete is not  called and the transaction is rolled back.
        scope.Complete();
    }

    // The returnValue is greater than 0 if the transaction committed.
    if (returnValue > 0)
    {
        writer.WriteLine("Transaction was committed.");
    }
    else
    {
        // You could write additional business logic here, for example, you can notify the caller 
        // by throwing a TransactionAbortedException, or logging the failure.
        writer.WriteLine("Transaction rolled back.");
    }

    // Display messages.
    Console.WriteLine(writer.ToString());

    return returnValue;
}

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0

Community Additions

ADD
Show:
© 2014 Microsoft