Enterprise Integration Solutions

124 Part II Message Endpoints

value in scenarios involving reporting, document versioning, and other tasks.

For example, if you want to save multiple versions of a contract, you can easily

accomplish this by using files. In addition, loading a file into memory as an

array can be an extremely fast method of accessing information. Files are also

useful for storing flat data when no hierarchical relationships exist.

As with many other technologies, file endpoints can be abused. For example,

if you create extremely large files or files that must be related to other files to

make sense, you will certainly cause problems further down the road. Managed

properly, however, files can provide a simple-to-use, extremely fast method of

storing information.

Files and the File System in .NET

Much of this chapter will focus on handling and manipulating files and the file

system in .NET. This section will provide a brief introduction to using files and

the file system within the Microsoft .NET Framework.

The core building block of file I/O in .NET is the System.IO.Stream

class. This is an abstract class inherited by the following classes in the .NET

Framework:

■ System.IO.FileStream

■ System.IO.MemoryStream

■ System.Security.Cryptography.CryptoStream

■ System.NET.Sockets.NetworkStream

■ System.IO.BufferedStream

A stream is a flow of bytes to and from a data store such as a file, memory

address, and so on. A FileStream is used for accessing files randomly or sequen-

tially and storing them in a byte array. The following function can convert a

string to a byte array for use with a FileStream object:

Private Function StringToBytes(ByVal aString As String) As Byte()

Dim aBuffer(aString.Length - 1) As Byte

Dim aEncoder As New System.Text.ASCIIEncoding()

aEncoder.GetBytes(aString, 0, aString.Length, aBuffer, 0)

Return aBuffer

End Function

Although you can convert types to and from other types, as just shown,

to use the FileStream you will need to write a function to convert each type

to and from a byte array. Fortunately, the .NET Framework provides the

System.IO.StreamReader, System.IO.StreamWriter, System.IO.BinaryReader, and