Layers & Tiers

Lec - 41

Layers & Tiers Layers are merely logical groupings of the software

components that make up the application or service.

Whereas tiers refer to the physical residence of those layers (hardware)

In general, Layers – represents logical view of application Tiers – represents physical view of application

However, both terms are used interchangeably.

Layers

Figure shows a simplified view of one application and its layers.

Tiers

Client machine

Server machine

DB machine

Presentation Layer

Web Layer

Business Layer

EIS Layer

browser

Web server

Applicationserver

DB server

Layers [1]

Presentation layer

Collects user inputs

Validates user inputs

Presents the results of a computation

Controls the screen flow

Layers [2]

Business Layer

Concerned with the application specific functionality

Used to implement business rules and to perform business tasks

For example, in a banking system, banking functions such as opening an account, calculation of Tax, etc.

Layers [3]

Data Layer

Concerned with the management of the data & data sources of the system.

Data sources can be database, XML , web services, flat file etc.

Encapsulates data retrieval & storage logic

For example, the address book application needs to retrieve all person records from a database to display them to the user

Layers Support in Java

JSP / ServletsFrameworks(Struts,JSF etc)

HTML/Applets

JavaBeans / EJB

Server Presentation

Client Presentation

Business

Layers Java/J2EE Technology

DAO / ConnectorsData

Java 2 Enterprise Edition(J2EE)

What is J2EE?

Open and standard based platform for:

Development & deployment of n-tier web based and component based enterprise applications

Reusability, enhance-ability, scalability & interoperability

J2EE Suite Core technology:

Container infrastructure, language and environment support

Web Technology Java Servlets JavaServer Pages (JSP) JavaServer Pages Standard Tag Library (JSTL) JavaServer Faces (JSF)

Platform services Security Transactions Resources Connectors Java Message Service

And extensive support for XML technology Enterprise Java Bean (EJB) technology etc.

J2EE Distributed Multi-tiered Applications

J2EE :Multi-tiered Applications

J2EE :Multi-tiered Applications

J2EE :Multi-tiered Applications

servlets

Client TierCommunication Options

Communication with Business Tier

Case Study: Matrix Multiplication

Using Layers

Case Study: Matrix Multiplication

Problem Statement Calculate product of two matrices of order 2

* 2 Result of multiplication should be stored

in DB as well as shown to the user.

Case Study: Matrix Multiplication

Format Input format

input will be in 4,2,6,5 format separated by commas where 4,2 represents entries of the first row

Display format Displays the matrix as a square

Storage format Matrix will be stored as a string

Matrixinput.jsp

Matrixresult.jsp

ControllerServlet

MatrixMultiplier

MatrixDAO

Matrix

Beann

Business layer

Data layer

Controller layer

Server sidePresentation layer

HTMLClient sidePresentation layer

Matrix Multiplication: Layer by Layer View

Case Study: Matrix Multiplication

Example Code

netBeans4.1 Project