C# 4 and .NET 4

610 ❘ ChaPTer 23 system.trAnsActiOns
}
}
}
Trace.WriteLine("Error: " + ex.Message);
tx.Rollback();
}
finally
{
connection.Close();
}
If you have multiple commands that should run in the same transaction, every command must be associated
with the transaction. Because the transaction is associated with a connection, every one of these commands
must also be associated with the same connection instance. ADO.NET transactions do not support
transactions across multiple connections; it is always a local transaction associated with one connection.
When you create an object persistence model using multiple objects, for example, classes Course
and CourseDate , which should be persisted inside one transaction, it gets very diffi cult using ADO.NET
transactions. Here, it is necessary to pass the transaction to all the objects participating in the
same transaction.
ADO.NET transactions are not distributed transactions. In ADO.NET transactions, it
is diffi cult to have multiple objects working on the same transaction.
system.enterpriseservices
With Enterprise Services, you get a lot of services for free. One of them is automatic transactions.
Using transactions with System.EnterpriseServices has the advantage that it is not necessary to deal
with transactions explicitly; transactions are automatically created by the runtime. You just have to add the
attribute [Transaction] with the transactional requirements to the class. The [AutoComplete] attribute
marks the method to automatically set the status bit for the transaction: if the method succeeds, the success
bit is set, so the transaction can commit. If an exception happens, the transaction is aborted:
using System;
using System.Data.SqlClient;
using System.EnterpriseServices;
using System.Diagnostics;
namespace Wrox.ProCSharp.Transactions
{
[Transaction(TransactionOption.Required)]
public class CourseData: ServicedComponent
{
[AutoComplete]
public void AddCourse(Course course)
{
var connection = new SqlConnection(
Properties.Settings.Default.CourseManagementConnectionString);
SqlCommand courseCommand = connection.CreateCommand();
courseCommand.CommandText =
"INSERT INTO Courses (Number, Title) VALUES (@Number, @Title)";
connection.Open();
try
{
courseCommand.Parameters.AddWithValue("@Number", course.Number);
courseCommand.Parameters.AddWithValue("@Title", course.Title);
courseCommand.ExecuteNonQuery();
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