conversation

Students are a little confused after taking a lecture specially when it comes to Information Technology.So after the Systems Engineering course lecture on system architecture,a student has certain queries on the particular topic.No guesses ,the student is myself and am presenting it in the form of a dialogue

Student: Dr. Mitra we had a lecture on web based architecture. Can you just explain that to me again because I am not very clear on that ?

Doctor: Ok. First we need to understand what is system architecture?

Student:Ok

Doctor:System architecture refers to the architecture of a specific construction or system. System architecture corresponds to "architecture as a product." It is the result of a design process for a specific system and specifies the functions of components, their interfaces, their interactions, and constraints. This specification is the basis for detailed design and implementation steps.

Student: Ok

Doctor: There are various types of architecture .They are one tier architecture, two tier architecture , three tier architecture and multi tier architecture system.

Student: Right Doctor.

Doctor:A one-tier application is simply a program that doesn't need to access the network while running. Most simple desktop applications, like word processors or compilers, fall into this category. One-tier architecture has a huge advantage: simplicity. One-tier applications don't need to handle any network protocols, so their code is simpler. Such code also benefits from being part of an independent operation. It doesn't need to guarantee synchronization with faraway data, nor does it need exception-handling routines to deal with network failure, bogus data from a server, or a server running different versions of a protocol or program.

Moreover, a one-tier application can have a major performance advantage. The user's requests don't need to cross the network, wait their turn at the server, and then return. This has the added effect of not weighing down your network with extra traffic, and not weighing down your server with extra work.

Student: Ok.

Doctor: A two-tier architecture actually has three parts: a client, a server, and a protocol. The protocol bridges the gap between the client and server tiers. The two-tier design is very effective for network programming as well as for GUI programs, in which you can allocate functionality to the host. Traditionally, GUI code lives on the client host, and the so-called business logic lives on the server host. This allows user feedback and validation to occur on the client, where turnaround is quick; in the process, precious network and server resources are preserved.

Student:What is GUI Doctor?

Doctor:Graphic User Interface

Two tier architecture consists of a server which connects user machines containing business applications through local area network .It has a server which stores data. The applications are stored on individual machines. The advantage of such an architecture is it does not place burden on server machines when there are many users but it requires higher bandwith which slows down the applications.

Student : Ok

Doctor:A three-tier architecture introduces a server or an agent between the client and the server. The role of the agent is manyfold. It can provide translation services (as in adapting a legacy application on amainframe to a client/server environment), metering services (as inacting as a transaction monitor to limit the number of simultaneousrequests to a given server), or intellegent agent services (as inmapping a request to a number of different servers, collating the results, and returning a single response to the client.

In this architecture the application is separated into two parts . For example-SAP. In this the GUI is loaded in one part of the application and the operations will happen in the other application. The fundamentals will change in the business applications.

Student: Ok

Doctor:In software engineering, multi-tier architecture (often referred to as n-tier architecture) is a client-server architecture in which an application is executed by more than one distinct software agent. For example, an application that uses middleware to service data requests between a user and a database employs multi-tier architecture.

This architecture enables use of an application server to:

Validate the credentials of a client, such as a Web browser

Connect to a database server

Perform the requested operation

Student: Can you elaborate it Doctor ?

In a multi tier architecture, business applications want to communicate with the end user. It has to communicate through the web server. Here we change the GUI to web browser. It does not need specialist software at each location but the business application has to be web enabled.

Student: Thanks Doctor.I got a better understanding of the whole architecture system