11.1 Introduction

You can't always expect your customer to have the same bandwidth as your office LAN. Huge numbers of people still use modem connections, and some use mobile GPRS devices with even lower connection speeds.

These customers will only buy your software if it works at a speed that is at least usable and does not frustrate them. Online services with slow loading times will infuriate casual Web users and drive away potential customers. Conversely, people will pay more for better performance. To give an example, VNC (www.realvnc.com) is free, under general public license (GPL), whereas client licenses for Microsoft Terminal Services (MTS) are certainly not free. Both pieces of software allow you to control another computer remotely, but many people still opt for MTS. Why? Performance. MTS provides more fluid control over the remote computer than VNC over the same bandwidth.

This chapter is largely devoted to two different performance-enhancing techniques. The first section of the chapter covers a technology known as multicast, the ability to send one piece of data to more than one recipient simultaneously. The second section deals with data compression and decompression. This is the ability to convert a block of data into a smaller block of data and then return this to either an exact or near copy of the original data.

11.2 Tricks and Tips to Increase Performance

Performance increases can often be made by simple changes to how data is moved between client and server. In some cases, these techniques...