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TransactionScope.Dispose Method

Ends the transaction scope.

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

public void Dispose()

Implements

IDisposable.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 3rd party RDBMS 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();

    try
    {
        // 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))
            {
                // 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))
                {
                    // 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);
                }
            }

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

        }

    }
    catch (TransactionAbortedException ex)
    {
        writer.WriteLine("TransactionAbortedException Message: {0}", ex.Message);
    }
    catch (ApplicationException ex)
    {
        writer.WriteLine("ApplicationException Message: {0}", ex.Message);
    }

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

    return returnValue;
}

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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