Advanced Programming Rabie A. Ramadan [email protected] 7.

Advanced Programming

Rabie A. [email protected]

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Topics to be Covered

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JAVA Naming and Directory Interface (JNDI)http://java.sun.com/products/jndi/tutorial/

Java Design Patterns

JAVA Naming and Directory Interface (JNDI)

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A naming service associates names with objects. Thus, you can look up an object by its name.

A directory service associates names and attributes with objects. Thus, you not only can look up an object by its name but also get the object's attributes or search for the object based on its attributes.

Common Naming/directory services:• DNS• RMI Registry• CORBA naming service• Lightweight Directory Access Protocol (LDAP)• OS File system.• Windows registry• Windows Active Directory

JNDI provides a unified approach (API) to access any naming/directory service.

JNDI Overview

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JNDI is an Application Programming Interface (API) that provides naming and directory functionality to JAVA applications.

It is defined to be independent of any specific directory service implementation. Thus a variety of directories--new, emerging, and already deployed--can be accessed in a common way.

Java 2 SDK, v1.3 already includes the JNDI classes. More service providers can be implemented or downloaded from Sun’s website.

Javax.naming package:

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Context The javax.naming package defines a Context

interface, which is the core interface for looking up, binding/unbinding, renaming objects and creating and destroying subcontexts.

The most commonly used operation is lookup(). You supply lookup() the name of the object you want to look up, and it returns the object bound to that name.

Printer printer = (Printer)ctx.lookup("treekiller");

printer.print(report);

Java Design Patterns

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Java Design Patterns

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Design Patterns have two main usages in software development:

Common platform for developersDesign patterns provide a standard terminology and are specific to

particular scenario

For example, a singleton design pattern signifies use of single object so all developers familiar with single design pattern will make use of single object and they can tell each other that program is following a singleton pattern.

Best Practices• Design patterns have been evolved over a long period of time and they

provide best solutions to certain problems faced during software development.

Types of Design Pattern

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there are 23 design patterns in three different categories :

Creational Patterns• A way to create objects while hiding the creation logic, rather

than instantiating objects directly using new operator.

Structural Patterns• concern class and object composition. Concept of inheritance is

used to compose interfaces and define ways to compose objects to obtain new functionalities.

Types of Design Pattern

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Behavioral Patterns• These design patterns are specifically concerned with

communication between objects.

Factory Pattern

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Comes under creational pattern as this pattern provides one of the best ways to create an object

Implementation- Create a Shape interface and concrete classes implementing the

Shape interface.

- A factory class ShapeFactory is defined as a next step.

- FactoryPatternDemo, our demo class will use ShapeFactory to get a Shape object. It will pass information (CIRCLE / RECTANGLE / SQUARE) to ShapeFactory to get the type of object it needs.

Factory Pattern- Class Diagram

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Factory Pattern- Implementation

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Step 1: Create an interface.

Factory Pattern- Implementation

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Step 2: Create concrete classes implementing the same interface.

Factory Pattern- Implementation

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Factory Pattern- Implementation

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Step 3 : Create a Factory to generate object of concrete class based on given information.

Factory Pattern- Implementation

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Step 4: Use the Factory to get object of concrete class by passing an information such as type.

Factory Pattern- Implementation

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Step 5: Verify the output.

Singleton Design Pattern

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Creational pattern as this pattern provides one of the best way to create an object.

Involves a single class which is responsible to create its own object while making sure that only single object get created.

Singleton Design Pattern

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Implementation• SingleObject class have

its constructor as private and have a static instance of itself.

• SingleObject class provides a static method to get its static instance to outside world

Singleton Design Pattern

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Step 1: Create a Singleton Class

Singleton Design Pattern

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Step 2: Get the only object from the singleton class.

Singleton Design Pattern

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Step 3: Verify the output

Prototype Design Pattern

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Comes under creational pattern

Creating duplicate object while keeping performance in mind.

Involves implementing a prototype interface which tells to create a clone of the current object.

This pattern is used when creation of object directly is costly.

Prototype Design Pattern

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Implementation

Create an abstract class Shape and concrete classes extending the Shape class.

A class ShapeCache is defined as a next step which stores shape objects in a Hashtable and returns their clone when requested.

PrototypPatternDemo, our demo class will use ShapeCache class to get a Shape object.

Prototype Design Pattern

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Class Diagram

Prototype Design Pattern

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Step 1: Create an abstract class implementing Clonable interface.

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Prototype Design Pattern

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Step 2: Create concrete classes extending the above class.

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Prototype Design Pattern

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Prototype Design Pattern

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Prototype Design Pattern

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Step 3: Create a class to get concrete classes from database and store them in a Hashtable.

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Prototype Design Pattern

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Prototype Design Pattern

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Step 4: PrototypePatternDemo uses ShapeCache class to get clones of shapes stored in a Hashtable.

Prototype Design Pattern

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Step 5: Verify the output.