Layers & Tiers Umair Javed 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 Presentation Layer Web Layer Business Layer EIS Layer browser Client machine Web server Web Layer Server machine Application server Business Layer DB server EIS Layer DB machine

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

Frameworks(Struts,JSF etc) Layers Support in Java Layers Java/J2EE Technology Client Presentation HTML/Applets JSP / Servlets Frameworks(Struts,JSF etc) Server Presentation Business JavaBeans / EJB Data DAO / Connectors

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: Web Technology Platform services 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 Tier Communication 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

Matrix Multiplication: Layer by Layer View Client side Presentation layer HTML Matrixresult .jsp Matrixinput .jsp Server side Presentation layer MatrixBeann ControllerServlet Controller layer MatrixMultiplier Business layer Data layer MatrixDAO

Case Study: Matrix Multiplication Example Code netBeans4.1 Project