Limitations of two-tier client-server patterns

The following are some of the main limitations of client-server patterns:

• Limited extensibility, scalability, and reliability: In most of the implementations, application data and business logic reside on the same central server. This aspect impacts the system extensibility, scalability, and reliability.
• Excessive network bandwidth usage: communication between and the client and the server consumes excessive bandwidth. Request and response data often need to be converted to a common format as they might have a different format of representation on the client side and the server side. This aspect also contributes to additional traffic.

To overcome these limitations of the two-tier client server pattern, three-tier/multi-tier client-server architecture was developed. Most of the applications of the present day, which are developed using the client-server architecture, are based on the three-tire/multi-tier architectural model, which is discussed in the next section.

Because of the slight difference in their architecture, three-tier and multi-tiered architectures are handled as separate topics in this chapter, though they may be referred to interchangeably in many other forums.