Web Technologies - Old Questions

1.  Explain the 2-Tier, 3-Tier and n-Tier technology with its architecture.

2-Tier Architecture

2-tier architecture is used to describe client/server systems where the client requests resources and the server responds directly to the request, using its own resources. This means that the server does not call on another application in order to provide part of the service. It runs the client processes separately from the server processes, usually on a different computer.

3-Tier Architecture

In 3-tier architecture, there is an intermediary level, meaning the architecture is generally split up between:

– A client, i.e. the computer, which requests the resources, equipped with a user interface (usually a web browser) for presentation purposes

– The application server (also called middleware), whose task it is to provide the requested resources, but by calling on another server

– The data server, which provides the application server with the data it requires.

N-Tier Architecture (multi-tier)

N-tier architecture (with N more than 3) is really 3 tier architectures in which the middle tier is split up into new tiers. The application tier is broken down into separate parts. These parts are differs from system to system. The primary advantage of N-tier architectures is that they make load balancing possible. Since the application logic is distributed between several servers, processing can then be more evenly distributed among those servers. N-tiered architectures are also more easily scalable, since only servers experiencing high demand, such as the application server, need be upgraded. The primary disadvantage of N-tier architectures is that it is also more difficult to program and test an N-tier architecture due to its increased complexity.