Tilak A Varma

• Sep 26th, 2007

 

Three tier architecture deals with three layers. Presentation Layer, Control Layer and Database Layer(Model layer in generic) Presentation Layer deal with all front end pages which are developed with JSP, HTML, JavaScript, CSS, JSF(new), AJAX(new) like this.
We call this as front end because..this is only layer visible to the client who ever use the web application we created. They are not bothered about the control layer and model layer.

Now Coming to Control layer, this is the place where actual magic works out. Here we take a request from Presentation Layer and do all magic and if any data is provided from presentation layer , we will write the logic to store that data in to Database Layer(yet to discuss about this layer)If client needs and data we will write the logic to fetch the data from the database layer.

Coming to Database Layer(trash can) we will store all the good and bad in this layer
we need to create tables with primary keys and foreign keys and keeps the trash can ready..so when ever the data comes from the presentation layer we will keep that into our trash can and if any person requests data we will fetch from this can.

We can also make 4 tier by separating the control layer into two parts like..one part is to just delegate the requests to all layers and the other part just to perform business logic. When we are using 3 tier and use servlet(no matter ActionServlet or HttpServlet)this servlet is responsible to perform bussiness logic and after that it should delegate the request to Presentation layer(like success page or failure page) and also to database layer..