2.1 Introduction

This chapter lays the foundation for virtually every networking example contained in this book. Without a working knowledge of how .NET handles I/O, it may prove difficult to adapt the code examples in this book to your own needs.

I/O applies to network data transfers, as well as saving and loading to your computer's hard disk Later chapters will describe how to perform network transfers; however, this chapter will be concerned with the underlying I/O operations that are common to both types of transfers. The first half of this chapter will demonstrate how to read and write to disk, using .NET streams.

The second half of this chapter develops the stream concept by demonstrating how to convert complex objects, such as database queries, into a format that can be written to a .NET stream.

2.2 Streams

In order to provide similar programmatic interfaces to the broad range of I/O devices with which a programmer has to contend, a stream-based architecture was developed in .NET. I/O devices can be anything from printers to hard disks to network interfaces.

Not all devices support the same functions. For example, it is possible to read only the second half of a 1-Mb file, but not possible to download only the second half of a Web page. Therefore, not all streams support the same methods.

Properties such as canRead(), canSeek(), and canWrite() indicate the capabilities of the stream when applied to a particular device.

The most important stream in the context...