C# 4 and .NET 4

summary ❘ 635
txHandle, IntPtr.Zero, IntPtr.Zero);
}
}
}
return new FileStream(fileHandle, FileAccess.Write);
code snippet FileSystemTransactions/TransactedFile.cs
Now it is very easy to use the transactional API from .NET code. You can create an ambient transaction
with the TransactionScope class and use the TransactedFile class within the context of the ambient
transaction scope. If the transaction is aborted, the file is not written. If the transaction is committed, you
can find the file in the temp directory:
using System;
using System.IO;
using System.Transactions;
namespace Wrox.ProCSharp.Transactions
{
class Program
{
static void Main()
{
using (var scope = new TransactionScope())
{
FileStream stream = TransactedFile.GetTransactedFileStream(
"sample.txt");
var writer = new StreamWriter(stream);
writer.WriteLine("Write a transactional file");
writer.Close();
}
}
}
}
if (!Utilities.AbortTx())
scope.Complete();
code snippet Windows7Transactions/Program.cs
Now you can use databases, volatile resources, and files within the same transaction.
summary
In this chapter, you learned the attributes of transactions and how you can create and manage transactions
with the classes from the System.Transactions namespace.
Transactions are described with ACID properties: atomicity, consistency, isolation, and durability. Not all
these properties are always required, as you have seen with volatile resources that don’t support durability
but have isolation options.
The easiest way to deal with transactions is by creating ambient transactions and using the
TransactionScope class. Ambient transactions are very useful working with the ADO.NET data adapter
and the ADO.NET Entity Framework, where usually you do not open and close database connections
explicitly. ADO.NET is covered in Chapter 30, “Core ADO.NET.” Entity Framework is explained in
Chapter 31, “ADO.NET Entity Framework.”
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