Similarities & Differences Between Architectures{2}

by Jasmine C
The article I read about discussed the different attributes associated between a two-tier and three-tier architecture.   Before the use of three-tier systems, two-tier systems were by businesses to access their database.  Two-tier systems consists of two layers, the use layer and the server layer, where the server is where most of the work is being performed.  According to the article, the main disadvantage of the two-tier system is that it has limited scalability. This means that businesses cannot “support more than 100 simultaneous users” (Dickman) and this is a problem because hopefully as their business grows, they would need more users to access their system.  So they created a three-tier system.  This is very similar to a two-tier except the additional layer. According to the article, this additional layer removes the business processing from the client and places it on another server.  The three layers each contains their own hardware/software and each execute their own functions.  If you have a two-tier system and are contemplating switching to a three-tier system, there are ways for you to position your current systems for the use of three-tier system in the future.  The article states that when you begin to design your three-tier system, a business should have documents relating to the business, data and operational requirements. This makes it easier for the business to design their database requirements because they just base it on their business requirements.

I liked this article because not only did it discuss the difference between the two systems, but it also discussed the many possibilities a business has when designing their three-tier architecture. For example, the article states that when regarding the architecture ” a nearly unlimited range of technology components might be identified. For example, for the server, consider specifying server hardware and operating system” (Dickman).  The article goes on to list different types of software that could be used like server applications development, analysis and design tools, and many more. For a business designing their three-tier system, this article could act as a great guide/reference.

In class we were discussing the these two architectures. When a business decides to use either one of these systems, they should consider their own requirements before anything else. The reason being because they should not have to spend their time and resources on designing a three-tier system when all they need is a two-tier.  If maybe in the future they expect to use a three-tier system, like the article stated, the can position their two-tier system for later transition to three-tier.


Dickman, A. (1995). Two-tier versus three-tier apps. InformationWeek, 74. Retrieved March 4, 2012 from