Abstract Factory Design Pattern

Abstract Factory - Offers the interface for creating a family of related objects, without explicitly specifying their classes.

Factory Method Common usage

Along with singleton pattern the factories are the most used patterns. Almost any application has some factories. Here are a some examples:
- factories providing an xml parser: javax.xml.parsers.DocumentBuilderFactory or javax.xml.parsers.SAXParserFactory 

Factory Method pattern When to use

Factory Method pattern should be used when:
- a framework delegate the creation of objects derived from a common superclass to the factory
- the base factory class does not know what concrete classes will be required to create - delegates to its subclasses the creation of concrete objects
- factory subclasses subclasses are aware of the concrete classes that must be instantiated

Factory method pattern, compared to Factory pattern replace the factory with an abstract class and a set of concrete factories subclasses. The subclasses are responsible for creating concrete product objects; for factory method is possible adding new product classes without changing the abstract factory. The same result can be achieved for simplified factory pattern if reflection is used.

Factory Method Design Pattern

Defines an interface for creating objects, but let subclasses to decide which class to instantiate and Refers to the newly created object through a common interface.

Factory Design pattern common usage

Common Usage

Along with singleton pattern the factory is one of the most used patterns. Almost any application has some factories. Here are a some examples in java:
- factories providing an xml parser: javax.xml.parsers.DocumentBuilderFactory or javax.xml.parsers.SAXParserFactory
- java.net.URLConnection - allows users to decide which protocol to use

Factory pattern When to Use

Factory pattern should be used when: - a framework delegate the creation of objects derived from a common superclass to the factory - we need flexibility in adding new types of objects that must be created by the class

Singleton Design Pattern Common Usage

There are many common situations when singleton pattern is used:
- Logger Classes
- Configuration Classes
- Accesing resources in shared mode
- Other design patterns implemented as Singletons: Factories and Abstract Factories, Builder, Prototype

Factory(Simplified version of Factory Method) Design Pattern

Factory(Simplified version of Factory Method) - Creates objects without exposing the instantiation logic to the client andRefers to the newly created object through a common interface.

Singleton pattern how to use

Singleton pattern should be used when we must ensure that only one instance of a class is created and when the instance must be available through all the code. A special care should be taken in multithreading environments when multible threads must access the same resources throught the same singleton object.

Singleton Design Pattern

Singleton - Ensure that only one instance of a class is createdand Provide a global access point to the object.

What is Object-oriented design

Based on objects and their interrelationships
It starts with object types and then explores object attributes and actions.

Our context in this training is to handle Object oriented methodology

What is Data Driven

The structure of the software system is derived by mapping system inputs to outputs
Determine the data requirements of a business process

What is Structured design

1. Structured design is based on functional decomposition
2. It follows typically from dataflow diagram and associated processes descriptions created as part of Structured Analysis
3. In structured design we functionally decompose the processes in a large system (as described in DFD) into components (called modules) and organize these components in a hierarchical fashion (structure chart)

What is Software Design Process

It is a series of activities to be carried out to complete the design task

what are Software design methodologies

Structured
Data Driven
Object oriented

What are Design process activities

Architectural design
Interface design
Component design
Data structure design
Review
Design documentation
Programming (occasionally)

UML to Work

The ESU University wants to computerize their registration system

1. The Registrar sets up the curriculum for a semester
2. One course may have multiple course offerings
3. Students select 4 primary courses and 2 alternate courses
4. Once a student registers for a semester, the billing system is notified so the student may be billed for the semester
5. Students may use the system to add/drop courses for a period of time after registration
6. Professors use the system to receive their course offering rosters
7. Users of the registration system are assigned passwords which are used at logon validation

What are levels of Normalization

The first three levels in normalising a database are:
First Normal Form (1NF): There should be no repeating groups in a table.
Second Normal Form (2NF): No non-key fields may depend on a portion of the primary key.
Third Normal From (3FN): No fields may depend on other non-key fields. In other words, each field in a record should contain information about the entity that is defined by the primary key.

Database design Keys

Primary key enforce entity integrity by uniquely identifying entity instances

Foreign key enforce referential integrity by completing an association between two entities

Candidate key is an attribute that can be uniquely used to identify a database record (Ex. Social security number in employee table)

Composite Key is combination of more than one attribute which uniquely identify a database record

Unique key is an attribute which can be used to identify a single record

What are Basic Constructs of E-R Model

Entity
Entity is a data object about which information is to be collected. (ex.EMPLOYEE, PROJECT, INVOICE).
An entity is analogous to a table in the relational model.
Entities are classified as independent or dependent
An independent entity is one that does not rely on another for identification.
A dependent entity is one that relies on another for identification.

What is Normalization

The process of structuring data to minimize duplication and inconsistencies
The process usually involves breaking down a single table into two or more tables and defining relationships between those tables.

What is Entity-Relationship design Model

The ER model is a conceptual data model that views the real world as entities and relationships

Difference between Logical and Physical Data Modeling

Logical Data Model:
Entity
Attribute
Primary Key
Alternate Key
Inversion Key Entry
Rule
Relationship

Physical Data Model
Table
Column
Primary Key Constraint
Unique Constraint or Unique Index
Non Unique Index
Check Constraint, Default Value
Foreign Key

Data Modeling Development Cycle

Phase-1 : Gathering Business Requirements
Phase-2: Conceptual Data Modeling (CDM).
Phase-3: Logical Data Modeling (LDM).
Phase 4: Physical Data Modeling (PDM).
Phase 5: DB design

What is Anti design pattern

A pattern that tells how to go from a problem to a bad solution
Looks like a good idea, but which backfires badly when applied
A pattern that tells how to go from a bad solution to a good solution

What is Behavioral design pattern

Examples of Behavioral patterns include
Command pattern
Template method pattern
Observer pattern
And More

What is Structural Design pattern

Examples of Structural patterns include
Adapter pattern
Adapter pattern
Container pattern
Façade pattern
And more

What is Creational design pattern

Examples of Creational patterns include
Abstract factory pattern
Factory method pattern
Singleton pattern
And More

Types of design patterns in Software

Design patterns can be classified in terms of the underlying problem they solve
Architectural patterns-- expresses a fundamental structural organization or schema for software systems.
Creational patterns--that deal with object creation mechanisms, trying to create objects in a manner suitable to the situation
Structural patterns--ease the design by identifying a simple way to realize relationships between entities.
Behavioral patterns--identify common communication patterns between objects and increase flexibility in carrying out this communication
And More

UML Concepts

The UML may be used to:

1. Display the boundary of a system & its major functions using use cases and actors
2. Illustrate use case realizations with interaction diagrams
3. Represent a static structure of a system using class diagrams
4. Model the behavior of objects with state transition diagrams
5. Reveal the physical implementation architecture with component & deployment diagrams
6. Extend your functionality with stereotypes

What is the UML?

• UML stands for Unified Modeling Language

• The UML combines the best of the best from

1. Data Modeling concepts (Entity Relationship Diagrams)
2. Business Modeling (work flow)
3. Object Modeling
4. Component Modeling

• The UML is the standard language for visualizing, specifying, constructing, and documenting the artifacts of a software-intensive system

• It can be used with all processes, throughout the development life cycle, and across different implementation technologies

E-R Model data relation ship

Relationship
represents real world associations among one or more entities

What is Data Modeling in Software

A data model is a conceptual representation of the data structure that are required by a database.

The data model focuses on what data is required and how it should be organized rather than what operations will be performed on the data

What is Architectural design pattern

Examples of architectural patterns include:
Model-view-controller
Presentation-abstraction-control
Client-server
Service-oriented architecture
Pipeline (software)
And More

Why to design pattern in Software Architecture

Design patterns can speed up the development process by providing tested, proven development paradigms.
It allows developers to communicate using well-known, well understood names for software interactions

What is Design Patterns in Software

Design pattern is a general repeatable solution to a commonly occurring problem in software design
It is a description or template for how to solve a problem that can be used in many different situations