This document discusses software design patterns, which provide reusable solutions to common problems in software design. It covers creational patterns like singleton and abstract factory, structural patterns like adapter and bridge, and behavioral patterns like iterator and observer. Patterns help developers solve recurring problems in an elegant and reusable way by providing tried-and-tested solutions to common design problems. The document also discusses categories of patterns, their elements, and when to use different patterns.
The document discusses design patterns, including their definition, benefits, common myths, design principles, basic elements, categories, and the pattern life cycle. It provides examples of the Singleton and Observer patterns, and discusses how the Model-View-Controller pattern uses strategies like Observer, Strategy, and Composite. Experts recommend focusing on simplicity, practical extensibility over hypothetical generality, and adapting patterns to problems rather than following them rigidly.
The document discusses the composite design pattern, which allows clients to treat individual objects and compositions of objects uniformly. It can be used to represent recursive data structures like arithmetic expressions. The pattern involves defining components as objects in a tree structure, with leaf nodes as individual objects and composite nodes containing and managing child components. It allows operations to be applied uniformly to both leaf and composite nodes. The document provides examples and discusses implementation issues like where to declare child management methods.
Design patterns are known as best practices that the programmer can use to solve common problems when designing an application or system.
Singelton Design Pattern
Factory Design Pattern
Builder Design Pattern
Strategy Design Pattern
Iterator Design Pattern
Observer Design Pattern
Prototype Design Pattern
Command Design Pattern
Decorator Pattern
Proxy Pattern
Adapter Pattern
The document discusses software design patterns and how they can help address common problems that arise during design. It describes three main categories of patterns - creational, structural, and behavioral - and provides examples of specific patterns like Singleton, Factory, Adapter, and Bridge. The key benefits of design patterns are that they provide proven, reusable solutions to general problems and help create flexible, modular designs that can more easily adapt to changes.
Software Design Patterns. Part I :: Structural PatternsSergey Aganezov
In a nutshell, software design patterns are generally reusable solutions to a commonly occurring problems. And this says it all! We are going to learn when it is completely unnecessary for you to reinvent the wheel, and what are the best ways to approach each particular problem during software development process.
The document discusses several design patterns including Observer, State, Template Method, Memento, Command, Chain of Responsibility, Interpreter, Mediator, Iterator, Strategy, Visitor, Flyweight, and Singleton patterns. For each pattern, it provides the definition, participants, structure, intent, caveats, and examples.
This document discusses various structural design patterns including Adapter, Bridge, Composite, Decorator, Facade, Flyweight, and Proxy. It defines each pattern, provides examples of how and when to use each pattern, and in some cases includes UML diagrams. The document also discusses how the Decorator pattern can be used to solve the problem of creating specialized robot doctors in an automated hospital that each perform a core set of functions plus additional specialized functions.
The document discusses design patterns, including their definition, benefits, common myths, design principles, basic elements, categories, and the pattern life cycle. It provides examples of the Singleton and Observer patterns, and discusses how the Model-View-Controller pattern uses strategies like Observer, Strategy, and Composite. Experts recommend focusing on simplicity, practical extensibility over hypothetical generality, and adapting patterns to problems rather than following them rigidly.
The document discusses the composite design pattern, which allows clients to treat individual objects and compositions of objects uniformly. It can be used to represent recursive data structures like arithmetic expressions. The pattern involves defining components as objects in a tree structure, with leaf nodes as individual objects and composite nodes containing and managing child components. It allows operations to be applied uniformly to both leaf and composite nodes. The document provides examples and discusses implementation issues like where to declare child management methods.
Design patterns are known as best practices that the programmer can use to solve common problems when designing an application or system.
Singelton Design Pattern
Factory Design Pattern
Builder Design Pattern
Strategy Design Pattern
Iterator Design Pattern
Observer Design Pattern
Prototype Design Pattern
Command Design Pattern
Decorator Pattern
Proxy Pattern
Adapter Pattern
The document discusses software design patterns and how they can help address common problems that arise during design. It describes three main categories of patterns - creational, structural, and behavioral - and provides examples of specific patterns like Singleton, Factory, Adapter, and Bridge. The key benefits of design patterns are that they provide proven, reusable solutions to general problems and help create flexible, modular designs that can more easily adapt to changes.
Software Design Patterns. Part I :: Structural PatternsSergey Aganezov
In a nutshell, software design patterns are generally reusable solutions to a commonly occurring problems. And this says it all! We are going to learn when it is completely unnecessary for you to reinvent the wheel, and what are the best ways to approach each particular problem during software development process.
The document discusses several design patterns including Observer, State, Template Method, Memento, Command, Chain of Responsibility, Interpreter, Mediator, Iterator, Strategy, Visitor, Flyweight, and Singleton patterns. For each pattern, it provides the definition, participants, structure, intent, caveats, and examples.
This document discusses various structural design patterns including Adapter, Bridge, Composite, Decorator, Facade, Flyweight, and Proxy. It defines each pattern, provides examples of how and when to use each pattern, and in some cases includes UML diagrams. The document also discusses how the Decorator pattern can be used to solve the problem of creating specialized robot doctors in an automated hospital that each perform a core set of functions plus additional specialized functions.
The document discusses sequence diagrams in the Unified Modeling Language (UML). It describes how sequence diagrams are used to show the interactions between objects in sequential order. It outlines the key components of a sequence diagram, including lifelines to represent participating objects, messages to show interactions between lifelines, and combined fragments to depict alternatives and loops. The document provides examples of how to draw lifelines, messages, and depict synchronous versus asynchronous messages in a sequence diagram.
Creational patterns deal with object creation and aim to create objects in a suitable manner. There are three main creational patterns: the factory pattern, which provides a consistent interface for creating properly configured objects; the abstract factory pattern, which is a factory for factories and handles more complex situations; and the singleton pattern, which ensures a single instance of an object and consistency of data by restricting object instantiation.
Software Architecture and Project Management module III : PATTERN OF ENTERPRISEsreeja_rajesh
This document discusses various software architecture patterns. It begins by covering communication patterns, including the forward-receiver and client-dispatcher-server patterns. It then discusses structural patterns, including decorator, proxy, bridge, composite and others. For each pattern, it provides descriptions, examples, and UML diagrams. The document is focused on explaining different types of architectural patterns for software design.
Design patterns are optimized, reusable solutions to the programming problems that we encounter every day. A design pattern is not a class or a library that we can simply plug into our system; it's much more than that. It is a template that has to be implemented in the correct situation. It's not language-specific either. A good design pattern should be implementable in most—if not all—languages, depending on the capabilities of the language. Most importantly, any design pattern can be a double-edged sword— if implemented in the wrong place, it can be disastrous and create many problems for you. However, implemented in the right place, at the right time, it can be your savior.
This document discusses implementing object-oriented programming in Visual Basic .NET. It outlines objectives like identifying classes, objects, structures, abstract classes, interfaces and assemblies. It describes creating a class with members to store customer data, and a Windows form with controls to accept this data. The data will be stored in member variables of a Customer class instance. The form will have labels, textboxes and buttons. Entering data will instantiate the Customer class and store information in its members.
The document provides an overview of design patterns, including creational patterns. It defines the Abstract Factory pattern, which provides an interface for creating families of related or dependent objects without specifying their concrete classes. The Abstract Factory pattern allows for creating objects in a generic way and enforces creation constraints. It works by having a super-factory that creates other factories to generate related object types. The document outlines the intent, structure, collaboration and consequences of applying the Abstract Factory pattern, as well as how to implement and apply it to solve object creation problems in a flexible manner.
The document discusses several creational design patterns: Singleton, Factory, Abstract Factory, and Prototype. The Singleton pattern ensures that only one instance of a class exists. The Factory pattern abstracts object creation by defining a common interface for creating objects. The Abstract Factory pattern provides an interface for creating families of related objects without specifying their concrete classes. The Prototype pattern creates objects by cloning prototypes instead of using constructors.
Behavioral design patterns describe communication between objects. They include interpreter, iterator, mediator, observer, state, chain of responsibility, command, and template patterns. Interpreter represents grammar as class hierarchies. Iterator provides sequential access to aggregate objects. Mediator avoids direct references between dependent objects. Observer notifies objects of state changes. State encapsulates an object's behavior based on its internal state. Chain of responsibility links objects to handle requests. Command captures operations flexibly. Template expresses basic algorithms with variable steps.
An introduction to structural design patterns in object orientation. Suitable for intermediate to advanced computing students and those studying software engineering.
The SOLID Principles Illustrated by Design PatternsHayim Makabee
The goal of the SOLID design principles is to improve the Separation of Concerns, through weaker Coupling and stronger Cohesion. The main consequence should be software systems that are easier to maintain and to extend. However the definition of the SOLID principles is quite abstract, and some developers find it difficult to apply them in practice. In my talk I will show how well-known Design Patterns illustrate the application of the SOLID principles, and also show examples of how to follow these principles to Refactor and improve existing designs.
About the speaker:
Hayim Makabee was born in Rio de Janeiro. He immigrated to Israel in 1992 and completed his M.Sc. studies on Computer Sciences at the Technion. Since then he worked for several hi-tech companies, including also some start-ups. Currently he is a co-founder of the International Association of Software Architects (IASA) in Israel. Hayim is the author of a book about Object-Oriented Programming and has published papers in the fields of Software Engineering, Distributed Systems and Genetic Algorithms.
An introduction to creational design patterns in object orientation. Suitable for intermediate to advanced computing students and those studying software engineering.
The document provides information about UML (Unified Modeling Language), including its goals, why it is used, and common diagram types. UML is a standard language for specifying, constructing, and documenting software systems and business processes. It uses mainly graphical notations to express the design of software projects. Common UML diagram types include use case diagrams, class diagrams, interaction diagrams, state diagrams, activity diagrams, component diagrams, and deployment diagrams. Each diagram type shows different aspects of a system and allows developers and customers to view it from different perspectives.
The document discusses various design principles and patterns in Java including the Singleton, Factory Method, Prototype, and Abstract Factory patterns. It provides examples of when and how to apply each pattern, describing their structures, participants, collaborations and consequences. It also covers design principles such as the open-closed principle, dependency inversion, and interface segregation.
An introduction to behavioural design patterns in object orientation. Suitable for intermediate to advanced computing students and those studying software engineering.
Factory method, strategy pattern & chain of responsibilitiesbabak danyal
The Factory Method pattern defines an interface for creating an object, but lets subclasses decide which class to instantiate. It provides a way to delegate instantiation to subclasses by defining a factory method that returns an object of a product class. The Strategy pattern defines a family of algorithms, puts each of them in a separate class, and makes their objects interchangeable. Context uses a Strategy object to perform an algorithm without knowing its concrete class. The Proxy pattern provides a surrogate or placeholder for another object to control access to it. It protects the real subject object and controls its access.
The document discusses the composite pattern which allows objects to be grouped together into tree structures to represent part-whole hierarchies. The composite pattern lets clients treat individual objects and compositions of objects uniformly. It describes replacing implicit trees with composite by identifying implicit leaves and parents and replacing them with composite node instances. Benefits of the pattern are encapsulating repetitive instructions and simplifying construction, while liabilities include complicating designs when implicit trees are simpler. Implementation issues discussed include parent references, interfaces, operations, and relationships to other design patterns.
The document describes the Factory Method design pattern. It defines an interface for creating an object, but lets subclasses decide which class to instantiate. This allows a class to instantiate a derivation of another class without knowing the exact class. The document provides an example of using the Factory Method pattern to create different types of database connections at runtime depending on the database type.
Sharon Li has been chosen as the storyboard artist, sound designer, and editor based on her artistic talents and background in music. Gabby Orr will be the cinematographer, screenwriter, and producer due to her photography experience and writing background. Jack McGuinness will serve as the graphic designer, director, art director, and production designer since he is creative and enthusiastic about design, understands how shots affect viewers, and has become proficient in After Effects.
The document discusses sequence diagrams in the Unified Modeling Language (UML). It describes how sequence diagrams are used to show the interactions between objects in sequential order. It outlines the key components of a sequence diagram, including lifelines to represent participating objects, messages to show interactions between lifelines, and combined fragments to depict alternatives and loops. The document provides examples of how to draw lifelines, messages, and depict synchronous versus asynchronous messages in a sequence diagram.
Creational patterns deal with object creation and aim to create objects in a suitable manner. There are three main creational patterns: the factory pattern, which provides a consistent interface for creating properly configured objects; the abstract factory pattern, which is a factory for factories and handles more complex situations; and the singleton pattern, which ensures a single instance of an object and consistency of data by restricting object instantiation.
Software Architecture and Project Management module III : PATTERN OF ENTERPRISEsreeja_rajesh
This document discusses various software architecture patterns. It begins by covering communication patterns, including the forward-receiver and client-dispatcher-server patterns. It then discusses structural patterns, including decorator, proxy, bridge, composite and others. For each pattern, it provides descriptions, examples, and UML diagrams. The document is focused on explaining different types of architectural patterns for software design.
Design patterns are optimized, reusable solutions to the programming problems that we encounter every day. A design pattern is not a class or a library that we can simply plug into our system; it's much more than that. It is a template that has to be implemented in the correct situation. It's not language-specific either. A good design pattern should be implementable in most—if not all—languages, depending on the capabilities of the language. Most importantly, any design pattern can be a double-edged sword— if implemented in the wrong place, it can be disastrous and create many problems for you. However, implemented in the right place, at the right time, it can be your savior.
This document discusses implementing object-oriented programming in Visual Basic .NET. It outlines objectives like identifying classes, objects, structures, abstract classes, interfaces and assemblies. It describes creating a class with members to store customer data, and a Windows form with controls to accept this data. The data will be stored in member variables of a Customer class instance. The form will have labels, textboxes and buttons. Entering data will instantiate the Customer class and store information in its members.
The document provides an overview of design patterns, including creational patterns. It defines the Abstract Factory pattern, which provides an interface for creating families of related or dependent objects without specifying their concrete classes. The Abstract Factory pattern allows for creating objects in a generic way and enforces creation constraints. It works by having a super-factory that creates other factories to generate related object types. The document outlines the intent, structure, collaboration and consequences of applying the Abstract Factory pattern, as well as how to implement and apply it to solve object creation problems in a flexible manner.
The document discusses several creational design patterns: Singleton, Factory, Abstract Factory, and Prototype. The Singleton pattern ensures that only one instance of a class exists. The Factory pattern abstracts object creation by defining a common interface for creating objects. The Abstract Factory pattern provides an interface for creating families of related objects without specifying their concrete classes. The Prototype pattern creates objects by cloning prototypes instead of using constructors.
Behavioral design patterns describe communication between objects. They include interpreter, iterator, mediator, observer, state, chain of responsibility, command, and template patterns. Interpreter represents grammar as class hierarchies. Iterator provides sequential access to aggregate objects. Mediator avoids direct references between dependent objects. Observer notifies objects of state changes. State encapsulates an object's behavior based on its internal state. Chain of responsibility links objects to handle requests. Command captures operations flexibly. Template expresses basic algorithms with variable steps.
An introduction to structural design patterns in object orientation. Suitable for intermediate to advanced computing students and those studying software engineering.
The SOLID Principles Illustrated by Design PatternsHayim Makabee
The goal of the SOLID design principles is to improve the Separation of Concerns, through weaker Coupling and stronger Cohesion. The main consequence should be software systems that are easier to maintain and to extend. However the definition of the SOLID principles is quite abstract, and some developers find it difficult to apply them in practice. In my talk I will show how well-known Design Patterns illustrate the application of the SOLID principles, and also show examples of how to follow these principles to Refactor and improve existing designs.
About the speaker:
Hayim Makabee was born in Rio de Janeiro. He immigrated to Israel in 1992 and completed his M.Sc. studies on Computer Sciences at the Technion. Since then he worked for several hi-tech companies, including also some start-ups. Currently he is a co-founder of the International Association of Software Architects (IASA) in Israel. Hayim is the author of a book about Object-Oriented Programming and has published papers in the fields of Software Engineering, Distributed Systems and Genetic Algorithms.
An introduction to creational design patterns in object orientation. Suitable for intermediate to advanced computing students and those studying software engineering.
The document provides information about UML (Unified Modeling Language), including its goals, why it is used, and common diagram types. UML is a standard language for specifying, constructing, and documenting software systems and business processes. It uses mainly graphical notations to express the design of software projects. Common UML diagram types include use case diagrams, class diagrams, interaction diagrams, state diagrams, activity diagrams, component diagrams, and deployment diagrams. Each diagram type shows different aspects of a system and allows developers and customers to view it from different perspectives.
The document discusses various design principles and patterns in Java including the Singleton, Factory Method, Prototype, and Abstract Factory patterns. It provides examples of when and how to apply each pattern, describing their structures, participants, collaborations and consequences. It also covers design principles such as the open-closed principle, dependency inversion, and interface segregation.
An introduction to behavioural design patterns in object orientation. Suitable for intermediate to advanced computing students and those studying software engineering.
Factory method, strategy pattern & chain of responsibilitiesbabak danyal
The Factory Method pattern defines an interface for creating an object, but lets subclasses decide which class to instantiate. It provides a way to delegate instantiation to subclasses by defining a factory method that returns an object of a product class. The Strategy pattern defines a family of algorithms, puts each of them in a separate class, and makes their objects interchangeable. Context uses a Strategy object to perform an algorithm without knowing its concrete class. The Proxy pattern provides a surrogate or placeholder for another object to control access to it. It protects the real subject object and controls its access.
The document discusses the composite pattern which allows objects to be grouped together into tree structures to represent part-whole hierarchies. The composite pattern lets clients treat individual objects and compositions of objects uniformly. It describes replacing implicit trees with composite by identifying implicit leaves and parents and replacing them with composite node instances. Benefits of the pattern are encapsulating repetitive instructions and simplifying construction, while liabilities include complicating designs when implicit trees are simpler. Implementation issues discussed include parent references, interfaces, operations, and relationships to other design patterns.
The document describes the Factory Method design pattern. It defines an interface for creating an object, but lets subclasses decide which class to instantiate. This allows a class to instantiate a derivation of another class without knowing the exact class. The document provides an example of using the Factory Method pattern to create different types of database connections at runtime depending on the database type.
Sharon Li has been chosen as the storyboard artist, sound designer, and editor based on her artistic talents and background in music. Gabby Orr will be the cinematographer, screenwriter, and producer due to her photography experience and writing background. Jack McGuinness will serve as the graphic designer, director, art director, and production designer since he is creative and enthusiastic about design, understands how shots affect viewers, and has become proficient in After Effects.
This document provides an overview and instructions for using the SCImago Journal & Country Rank portal, which includes scientific indicators and rankings of journals and countries derived from the Scopus database. It describes how to search and filter journal and country rankings according to subject area, country, year, and other criteria. It also explains the various bibliometric indicators included in the journal and country profiles and comparison tools, such as the SJR indicator, H-index, citations per document, and more. Bubble charts can also be used to analyze and compare national scientific output based on various performance metrics.
A system called Lynkos links product providers and distribution channels in the financial services industry like investment planning, retirement planning, insurance, and banking. It aims to improve operational efficiency and growth support by streamlining processes between clients, financial advisors, local offices, sales networks, and product providers. Currently, paperwork and data related to clients undergoes many duplicate verification, data entry, and archiving steps as it moves between these entities, generating additional costs and delays. Lynkos changes this by allowing a single entry of client data that can then be accessed and shared by all related parties through integrated systems.
This document describes the features and capabilities of a client relationship management (CRM) solution for financial services organizations. It provides consolidated client information and documents, real-time data streaming from carriers, customizable notes and reminders, transaction management, business intelligence reporting, channel management, asset management, content management, and messaging capabilities. The CRM solution is web-based, compatible with third party systems, and designed for use by internal staff, sales teams, and end customers on multiple devices. It has undergone quality and security standards certification and is deployed globally by over 300 intermediary networks.
Advantage MRI - Letter of Recommendation 2016ccstrain
This letter is a recommendation for Chris from Norm Kaufman based on 15 years of working together. Norm appreciates Chris' thoughtful counsel that has helped solve real estate problems and ensure the smooth operation of Norm's businesses. Chris takes the time to understand how Norm's companies run and what is important to him. Chris goes out of his way to help Norm even when there is no pending transaction and always promptly and accurately answers any questions. Norm considers Chris both a friend and advisor and recommends him as a real estate professional.
Evan Silva has two jobs - one serving drinks at a bar where he hears a lot of information, and the other that is "very disruptive." The script opens with Evan in bed awake as his alarm goes off. He turns it off and there is a bag under his bed containing a gun and money. In the bathroom, Evan takes medication as he receives a phone call from his employer about another job.
La enfermedad de Quervain es una inflamación de los tendones del pulgar que causa dolor e irritación. Generalmente se produce por movimientos repetitivos del pulgar o la muñeca como resultado del trabajo. Los síntomas incluyen dolor en la muñeca del lado del pulgar que empeora con el movimiento. El diagnóstico se realiza mediante exploración física y pruebas de imagen como radiografías o resonancia magnética. La prevención implica alternar tareas, estiramientos e mejorar la postura.
Um número cada vez maior de empresas tem adotado metodologias ágeis para o desenvolvimento de software. Entretanto, algumas preocupações e dúvidas têm surgido ao realizar testes nesse paradigma. Esta palestra tem como objetivo
apresentar uma visão geral sobre testes ágeis, suas principais características, ferramentas utilizadas e alguns casos de sucesso de testes nesses ambientes.
Conhecendo as funções analogread, analogwrite e analogreferenceFábio dos Reis
O documento descreve as funções analogRead(), analogWrite() e analogReference() do Arduino. A função analogRead() lê valores de pinos analógicos, analogWrite() gera sinais PWM em pinos digitais e analogReference() configura a tensão de referência para leituras analógicas.
The document discusses internet addiction among children in Bangladesh. It notes that a large number of internet users are under 18 and use it primarily for social media and entertainment. The overuse of the internet can lead to physical issues like headaches as well as mental health problems when it dominates a child's life over school, family, and other responsibilities. The document recommends that parents monitor their children's internet usage, set clear rules and limits, and maintain open communication to prevent internet addiction.
This document contains information about computer memory and binary digits. It represents memory locations as boxes that can each hold a binary digit (0 or 1) in different positions, with the value shown. It also notes that a 32-bit computer processes four bytes (32 bits) at a time. Additionally, it defines common digital storage terms like bits, bytes, nibbles, words, and provides examples of byte multiples from kilobytes to terabytes.
Design patterns are commonly used to address problems relating to application architecture and design. The concept originated from Christopher Alexander's work noting common building design problems and solutions. Design patterns ensure problems are addressed through well-known solutions, and most problems have likely been solved before. Common patterns include observer/subject to separate user interface from business logic, singleton to control object construction, strategy to allow multiple algorithms, and template method to define an algorithm's structure. The facade pattern provides different views of subsystems to users by hiding implementation details. The command pattern encapsulates requests as objects with a known interface to decouple senders and receivers.
Design patterns are optimized, reusable solutions to the programming problems that we encounter every day. A design pattern is not a class or a library that we can simply plug into our system; it's much more than that. It is a template that has to be implemented in the correct situation. It's not language-specific either. A good design pattern should be implementable in most—if not all—languages, depending on the capabilities of the language. Most importantly, any design pattern can be a double-edged sword— if implemented in the wrong place, it can be disastrous and create many problems for you. However, implemented in the right place, at the right time, it can be your savior.
The document outlines structural design patterns including Adapter, Facade, Decorator, Composite, and Proxy patterns. It provides definitions and examples of how each pattern allows objects to be combined into larger structures. The key purpose of structural patterns is that they involve connections between objects and define how components should be structured to work together flexibly in a system.
The document discusses software architecture, including definitions, principles, patterns, and modeling techniques. It defines architecture as the structure of a system comprising software elements and relationships. Some key principles discussed are single responsibility, open/closed, and dependency inversion. Common patterns like MVC, layered, and multitier architectures are explained. The document also introduces Unified Modeling Language (UML) for modeling systems using diagrams like class, component, and package diagrams.
Design patterns provide general reusable solutions to common problems in software design. They help structure code and define the way components interact. Some key design patterns discussed in the document include Singleton, Strategy, Decorator, and State. The Singleton pattern ensures a class only has one instance, Strategy encapsulates algorithms to allow flexible changes, Decorator adds functionality dynamically at runtime, and State changes object behavior based on its internal state. Design patterns improve code organization, reuse, and maintenance.
This document provides an introduction to design patterns, including their motivation, history, definition, categories, and examples. Some key points:
- Design patterns solve common programming problems by describing reusable solutions that can be adapted for different situations.
- Common categories include creational, structural, and behavioral patterns. Example patterns discussed are Singleton, Decorator, Abstract Factory.
- Design patterns speed up development, promote code reuse, and make software more robust, maintainable and extensible. Resources for further information on design patterns are provided.
Object design is the process of refining requirements analysis models and making implementation decisions to optimize execution time, memory usage, and other performance measures. It involves four main activities: service specification to define class interfaces; component selection and reuse of existing solutions; restructuring models to improve code reuse; and optimization to meet performance requirements. During object design, interfaces are fully specified with visibility, type signatures, and contracts to clearly define class responsibilities.
The document discusses object-oriented design using UML. It describes the design process, including refining the analysis model into a design model with more implementation details. Key artifacts of design include interfaces, subsystems, and classes. Maintaining both analysis and design models is recommended for large, complex systems. Design axioms aim to maximize independence between components and minimize complexity. Corollaries provide guidelines for loosely coupled, single-purpose classes with strong mappings between analysis and design models.
This document discusses various JavaScript design patterns. It begins by defining design patterns as recurring solutions to common software design problems. It then covers types of patterns such as creational, structural, and behavioral. Specific patterns like module, revealing module, singleton, prototype, factory, facade, and observer are demonstrated. Benefits include reusability, communication, and encapsulation. Drawbacks include additional complexity and difficulty testing in some cases. Examples are provided to illustrate usage of the patterns.
Luis Valencia will give a presentation on applying Typescript design patterns to React/SPFx. He has 17 years of experience including 10 years in SharePoint. The session will focus on writing clean, maintainable code and not flashy user interfaces. It will cover common design patterns like singleton, abstract factory, builder, and factory method. It will also discuss SOLID principles and building shared code libraries. The presentation aims to teach developers how to write code that is easy for others to maintain.
The document discusses encapsulation in C++ and object-oriented design principles. It covers:
1) Encapsulation requires that classes have clearly defined external interfaces and hide implementation details. This reduces coupling between classes.
2) Functions and classes should minimize side effects by passing parameters as constants and returning values rather than references when possible.
3) References are generally preferable to pointers as they only provide access to an object's interface rather than its memory.
4) Constructors and destructors help classes encapsulate their own resource management by allocating resources during initialization and freeing them during destruction.
Nina Grantcharova - Approach to Separation of Concerns via Design Patternsiasaglobal
Separation of Concerns aims at managing complexity by establishing a well-organized system where each part adheres to a single and unique purpose while maximizing the system's ability to adapt to change and increasing developers' productivity. The goal of this presentation is to promote the understanding of the principle of Separation of Concerns and to provide a selected set of foundational patterns to aid software architects in the designing of maintainable and extensible systems.
Patterns (contd)Software Development ProcessDesign patte.docxdanhaley45372
Patterns (contd)
Software Development Process
Design patterns used to handle change
More time extending and changing code than developing it.
The Strategy design pattern handle change by selecting from a family of external algorithms rather than rewrite.
Design point: Make code closed for modification of code, but open for extension
Problem
Computer object created
Description Method returns
Getting a Computer
Problem
Program has to change every time
Customer changes options
Decorator Pattern
Wrapper code used to extend your core code
Extend a class dynamically at runtime
Decorator uses wrapper code to extend core functionality - decorating the code
Decorator Pattern
description() returns “You are getting a computer”
Wrapper description() returns
“You are getting a computer and a disk”
Wrapper description() returns
“You are getting a computer and a disk and a monitor”
Decorator Pattern
Core component: Computer
Variables holding computer objects should also be able to hold objects that wrap computer objects.
Extend the wrapper classes from the Computer class.
Abstract class cannot be instantiated
Ensures all wrappers are consistent
Developers have to provide their own description
Decorator Pattern
Method calls the core computer object’s
description method and adds “and a disk”
Decorator Pattern
Method calls the core computer object’s
description method and adds “and a disk”
Extend the core object by wrapping it in decorator wrappers. Avoids modification of the core code.
Each successive wrapper called the description method of the object it wrapped and added something to it.
Factory Pattern
Based on type, call the
Connection method
Factory Pattern
Create a method that returns the
correct connection type
Factory Pattern
New operator used to create OracleConnection objects.
New operator used to create SqlServerConnection objects, and MySqlConnection objects.
New operator to instantiate many different concrete classes
Code becomes larger and needs to be replicated in many places
Factor that code out into a method.
Code keeps changing
Encapsulate code into a factory object
Goal: Separate out the changeable code and leave the core code closed for modification
Building the Factory
Creating the Factory
FirstFactory class encapsulates the connection object creation
Pass to it the type of connection (“Oracle”, “SQL Server”,)
Use the factory object to create connection objects with a factory method named createConnection
Building the Factory
Create the FirstFactory class.
Save the type of the database, passed to the FirstFactory class’s constructor.
Object-creation code changes
Check which type of object to be created
(OracleConnection, SqlServerConnection,
and then create it.
Factory Class
Create the Abstract Connection Class
Core code should not be modified or has to be modified
as little as possible.
Using the connection object returned by the
new factory object
Use t.
The document discusses design patterns used in object-oriented programming. It describes common design patterns like factory method, singleton, observer, and adapter patterns. It also discusses principles for assigning responsibilities to objects like high cohesion and low coupling. The document provides examples of applying these patterns and principles to design software objects and systems.
The document discusses design patterns, which are reusable solutions to common software design problems. It provides examples of different types of patterns, including creational (Factory Method, Abstract Factory, Builder, Prototype, Singleton), structural (Adapter, Bridge, Composite, Decorator, Facade, Flyweight, Proxy), and behavioral (Chain of Responsibility, Command, Interpreter, Iterator, Mediator, Memento, Observer, State, Strategy, Template Method, Visitor) patterns. Each pattern is defined and an example problem and solution using the pattern is described.
Design patterns are best practices for solving common programming problems. This document discusses several design patterns categorized as creational, structural, and behavioral patterns. It provides examples of the singleton, factory, builder, prototype, decorator, proxy, adapter, iterator, observer, command, and strategy patterns. Each pattern is defined and examples are given for when to use each pattern and code snippets demonstrating their implementation.
This document discusses design patterns at the medium scale level between architectural patterns and programming language idioms. It provides an overview of different categories of design patterns including structural decomposition, organization of work, access control, management, and communication. It then focuses on explaining the whole-part pattern for structural decomposition and the master-slave pattern for organizing work. It describes the context, problem, solution, structure, dynamics, implementation, variants, examples, and consequences of these two patterns.
Detailed description and introduction to UML(Unified Modeling Language).Structural and behavioral modeling.Class Diagram, Object Diagram.Notation for building all kinds of UML diagrams.
Conversational agents, or chatbots, are increasingly used to access all sorts of services using natural language. While open-domain chatbots - like ChatGPT - can converse on any topic, task-oriented chatbots - the focus of this paper - are designed for specific tasks, like booking a flight, obtaining customer support, or setting an appointment. Like any other software, task-oriented chatbots need to be properly tested, usually by defining and executing test scenarios (i.e., sequences of user-chatbot interactions). However, there is currently a lack of methods to quantify the completeness and strength of such test scenarios, which can lead to low-quality tests, and hence to buggy chatbots.
To fill this gap, we propose adapting mutation testing (MuT) for task-oriented chatbots. To this end, we introduce a set of mutation operators that emulate faults in chatbot designs, an architecture that enables MuT on chatbots built using heterogeneous technologies, and a practical realisation as an Eclipse plugin. Moreover, we evaluate the applicability, effectiveness and efficiency of our approach on open-source chatbots, with promising results.
Programming Foundation Models with DSPy - Meetup SlidesZilliz
Prompting language models is hard, while programming language models is easy. In this talk, I will discuss the state-of-the-art framework DSPy for programming foundation models with its powerful optimizers and runtime constraint system.
The Microsoft 365 Migration Tutorial For Beginner.pptxoperationspcvita
This presentation will help you understand the power of Microsoft 365. However, we have mentioned every productivity app included in Office 365. Additionally, we have suggested the migration situation related to Office 365 and how we can help you.
You can also read: https://www.systoolsgroup.com/updates/office-365-tenant-to-tenant-migration-step-by-step-complete-guide/
Essentials of Automations: Exploring Attributes & Automation ParametersSafe Software
Building automations in FME Flow can save time, money, and help businesses scale by eliminating data silos and providing data to stakeholders in real-time. One essential component to orchestrating complex automations is the use of attributes & automation parameters (both formerly known as “keys”). In fact, it’s unlikely you’ll ever build an Automation without using these components, but what exactly are they?
Attributes & automation parameters enable the automation author to pass data values from one automation component to the next. During this webinar, our FME Flow Specialists will cover leveraging the three types of these output attributes & parameters in FME Flow: Event, Custom, and Automation. As a bonus, they’ll also be making use of the Split-Merge Block functionality.
You’ll leave this webinar with a better understanding of how to maximize the potential of automations by making use of attributes & automation parameters, with the ultimate goal of setting your enterprise integration workflows up on autopilot.
Ivanti’s Patch Tuesday breakdown goes beyond patching your applications and brings you the intelligence and guidance needed to prioritize where to focus your attention first. Catch early analysis on our Ivanti blog, then join industry expert Chris Goettl for the Patch Tuesday Webinar Event. There we’ll do a deep dive into each of the bulletins and give guidance on the risks associated with the newly-identified vulnerabilities.
[OReilly Superstream] Occupy the Space: A grassroots guide to engineering (an...Jason Yip
The typical problem in product engineering is not bad strategy, so much as “no strategy”. This leads to confusion, lack of motivation, and incoherent action. The next time you look for a strategy and find an empty space, instead of waiting for it to be filled, I will show you how to fill it in yourself. If you’re wrong, it forces a correction. If you’re right, it helps create focus. I’ll share how I’ve approached this in the past, both what works and lessons for what didn’t work so well.
Main news related to the CCS TSI 2023 (2023/1695)Jakub Marek
An English 🇬🇧 translation of a presentation to the speech I gave about the main changes brought by CCS TSI 2023 at the biggest Czech conference on Communications and signalling systems on Railways, which was held in Clarion Hotel Olomouc from 7th to 9th November 2023 (konferenceszt.cz). Attended by around 500 participants and 200 on-line followers.
The original Czech 🇨🇿 version of the presentation can be found here: https://www.slideshare.net/slideshow/hlavni-novinky-souvisejici-s-ccs-tsi-2023-2023-1695/269688092 .
The videorecording (in Czech) from the presentation is available here: https://youtu.be/WzjJWm4IyPk?si=SImb06tuXGb30BEH .
What is an RPA CoE? Session 1 – CoE VisionDianaGray10
In the first session, we will review the organization's vision and how this has an impact on the COE Structure.
Topics covered:
• The role of a steering committee
• How do the organization’s priorities determine CoE Structure?
Speaker:
Chris Bolin, Senior Intelligent Automation Architect Anika Systems
Driving Business Innovation: Latest Generative AI Advancements & Success StorySafe Software
Are you ready to revolutionize how you handle data? Join us for a webinar where we’ll bring you up to speed with the latest advancements in Generative AI technology and discover how leveraging FME with tools from giants like Google Gemini, Amazon, and Microsoft OpenAI can supercharge your workflow efficiency.
During the hour, we’ll take you through:
Guest Speaker Segment with Hannah Barrington: Dive into the world of dynamic real estate marketing with Hannah, the Marketing Manager at Workspace Group. Hear firsthand how their team generates engaging descriptions for thousands of office units by integrating diverse data sources—from PDF floorplans to web pages—using FME transformers, like OpenAIVisionConnector and AnthropicVisionConnector. This use case will show you how GenAI can streamline content creation for marketing across the board.
Ollama Use Case: Learn how Scenario Specialist Dmitri Bagh has utilized Ollama within FME to input data, create custom models, and enhance security protocols. This segment will include demos to illustrate the full capabilities of FME in AI-driven processes.
Custom AI Models: Discover how to leverage FME to build personalized AI models using your data. Whether it’s populating a model with local data for added security or integrating public AI tools, find out how FME facilitates a versatile and secure approach to AI.
We’ll wrap up with a live Q&A session where you can engage with our experts on your specific use cases, and learn more about optimizing your data workflows with AI.
This webinar is ideal for professionals seeking to harness the power of AI within their data management systems while ensuring high levels of customization and security. Whether you're a novice or an expert, gain actionable insights and strategies to elevate your data processes. Join us to see how FME and AI can revolutionize how you work with data!
Introduction of Cybersecurity with OSS at Code Europe 2024Hiroshi SHIBATA
I develop the Ruby programming language, RubyGems, and Bundler, which are package managers for Ruby. Today, I will introduce how to enhance the security of your application using open-source software (OSS) examples from Ruby and RubyGems.
The first topic is CVE (Common Vulnerabilities and Exposures). I have published CVEs many times. But what exactly is a CVE? I'll provide a basic understanding of CVEs and explain how to detect and handle vulnerabilities in OSS.
Next, let's discuss package managers. Package managers play a critical role in the OSS ecosystem. I'll explain how to manage library dependencies in your application.
I'll share insights into how the Ruby and RubyGems core team works to keep our ecosystem safe. By the end of this talk, you'll have a better understanding of how to safeguard your code.
Monitoring and Managing Anomaly Detection on OpenShift.pdfTosin Akinosho
Monitoring and Managing Anomaly Detection on OpenShift
Overview
Dive into the world of anomaly detection on edge devices with our comprehensive hands-on tutorial. This SlideShare presentation will guide you through the entire process, from data collection and model training to edge deployment and real-time monitoring. Perfect for those looking to implement robust anomaly detection systems on resource-constrained IoT/edge devices.
Key Topics Covered
1. Introduction to Anomaly Detection
- Understand the fundamentals of anomaly detection and its importance in identifying unusual behavior or failures in systems.
2. Understanding Edge (IoT)
- Learn about edge computing and IoT, and how they enable real-time data processing and decision-making at the source.
3. What is ArgoCD?
- Discover ArgoCD, a declarative, GitOps continuous delivery tool for Kubernetes, and its role in deploying applications on edge devices.
4. Deployment Using ArgoCD for Edge Devices
- Step-by-step guide on deploying anomaly detection models on edge devices using ArgoCD.
5. Introduction to Apache Kafka and S3
- Explore Apache Kafka for real-time data streaming and Amazon S3 for scalable storage solutions.
6. Viewing Kafka Messages in the Data Lake
- Learn how to view and analyze Kafka messages stored in a data lake for better insights.
7. What is Prometheus?
- Get to know Prometheus, an open-source monitoring and alerting toolkit, and its application in monitoring edge devices.
8. Monitoring Application Metrics with Prometheus
- Detailed instructions on setting up Prometheus to monitor the performance and health of your anomaly detection system.
9. What is Camel K?
- Introduction to Camel K, a lightweight integration framework built on Apache Camel, designed for Kubernetes.
10. Configuring Camel K Integrations for Data Pipelines
- Learn how to configure Camel K for seamless data pipeline integrations in your anomaly detection workflow.
11. What is a Jupyter Notebook?
- Overview of Jupyter Notebooks, an open-source web application for creating and sharing documents with live code, equations, visualizations, and narrative text.
12. Jupyter Notebooks with Code Examples
- Hands-on examples and code snippets in Jupyter Notebooks to help you implement and test anomaly detection models.
Northern Engraving | Nameplate Manufacturing Process - 2024Northern Engraving
Manufacturing custom quality metal nameplates and badges involves several standard operations. Processes include sheet prep, lithography, screening, coating, punch press and inspection. All decoration is completed in the flat sheet with adhesive and tooling operations following. The possibilities for creating unique durable nameplates are endless. How will you create your brand identity? We can help!
For the full video of this presentation, please visit: https://www.edge-ai-vision.com/2024/06/how-axelera-ai-uses-digital-compute-in-memory-to-deliver-fast-and-energy-efficient-computer-vision-a-presentation-from-axelera-ai/
Bram Verhoef, Head of Machine Learning at Axelera AI, presents the “How Axelera AI Uses Digital Compute-in-memory to Deliver Fast and Energy-efficient Computer Vision” tutorial at the May 2024 Embedded Vision Summit.
As artificial intelligence inference transitions from cloud environments to edge locations, computer vision applications achieve heightened responsiveness, reliability and privacy. This migration, however, introduces the challenge of operating within the stringent confines of resource constraints typical at the edge, including small form factors, low energy budgets and diminished memory and computational capacities. Axelera AI addresses these challenges through an innovative approach of performing digital computations within memory itself. This technique facilitates the realization of high-performance, energy-efficient and cost-effective computer vision capabilities at the thin and thick edge, extending the frontier of what is achievable with current technologies.
In this presentation, Verhoef unveils his company’s pioneering chip technology and demonstrates its capacity to deliver exceptional frames-per-second performance across a range of standard computer vision networks typical of applications in security, surveillance and the industrial sector. This shows that advanced computer vision can be accessible and efficient, even at the very edge of our technological ecosystem.
"Choosing proper type of scaling", Olena SyrotaFwdays
Imagine an IoT processing system that is already quite mature and production-ready and for which client coverage is growing and scaling and performance aspects are life and death questions. The system has Redis, MongoDB, and stream processing based on ksqldb. In this talk, firstly, we will analyze scaling approaches and then select the proper ones for our system.
zkStudyClub - LatticeFold: A Lattice-based Folding Scheme and its Application...Alex Pruden
Folding is a recent technique for building efficient recursive SNARKs. Several elegant folding protocols have been proposed, such as Nova, Supernova, Hypernova, Protostar, and others. However, all of them rely on an additively homomorphic commitment scheme based on discrete log, and are therefore not post-quantum secure. In this work we present LatticeFold, the first lattice-based folding protocol based on the Module SIS problem. This folding protocol naturally leads to an efficient recursive lattice-based SNARK and an efficient PCD scheme. LatticeFold supports folding low-degree relations, such as R1CS, as well as high-degree relations, such as CCS. The key challenge is to construct a secure folding protocol that works with the Ajtai commitment scheme. The difficulty, is ensuring that extracted witnesses are low norm through many rounds of folding. We present a novel technique using the sumcheck protocol to ensure that extracted witnesses are always low norm no matter how many rounds of folding are used. Our evaluation of the final proof system suggests that it is as performant as Hypernova, while providing post-quantum security.
Paper Link: https://eprint.iacr.org/2024/257
2. Motivation Building software using new frameworks is more complex And expensive There are many methodologies and frameworks to help developers build enterprise application The main problems are: Changes in business logic Technology updates Maintenance Building software is difficult Building reusable software is even harder!
3. Why Patterns? We need a common, tried-and-tested way of building and testing software Especially in those areas where common problems recur The aim is to make it easier to change and maintain software Other aims Developers adopt a common design principle Don’t waste time “hacking” your way into a solution Reference on structures that get the work done efficiently
4. Patterns and Anti-patterns A pattern is a general, re-usable solution to a common problem in software design Gamma, Erich; Richard Helm, Ralph Johnson, and John Vlissides (1995). Design Patterns: Elements of Reusable Object-Oriented Software. Addison-Wesley. ISBN 0-201-63361-2 (Gang-Of-Four Book) An anti-pattern is a commonly used pattern but is counterproductive or ineffective in practice Experienced OO designers, in general, do not try to solve a problem from first principles Instead, they prefer to reuse a solution that has worked in the past
5. What constitutes a pattern? A Pattern has 4 essential elements: A pattern name: Used to refer to a description of a design problem, its solutions and consequences using a descriptive alias. The alias allows us to communicate with other and design at a higher level of abstraction. The problem: It describes when to apply the pattern. It describes the context of the problem such as class/object structures symptomatic of bad design or a list of conditions that must be met before applying the pattern. The solution: describes the elements that make up the design, the relationships, responsibilities and collaborations. It does not describe a concrete implementation. It is an abstract description of the general arrangement that will solve the problem. The consequences: refer to the results and trade-offs or applying the pattern. They are used to judge the costs and benefits of applying the pattern. Consequences include impact on system flexibility, extensibility and portability.
6. Categories of Patterns Creational patterns Deal with object creation mechanisms Structural patterns Ease the design of defining relationships between entities Behavioral patterns Used to identify communication patterns between objects and increase flexibility when carrying out this communication
7. Creational Patterns We shall be looking at the following Creational Patterns Singleton Pattern Abstract Factory (Kit) Pattern
8. Structural Patterns In this section, we’ll discuss the following patterns Adapter (or Wrapper) Pattern Bridge Pattern Composite Pattern Decorator Pattern Façade Pattern
9. Behavioural Patterns These are some common behavioural patterns: Iterator Pattern Observer Pattern Strategy Pattern
10. Creational Patterns We shall be looking at the following Creational Patterns Singleton Pattern Abstract Factory (Kit) Pattern
11. The Singleton Pattern I Provides a single object throughout the lifetime of an application Provides a single access point to the object An example would be to have one database connection per client application Used when: There must only be one instance of a class Clients need one single way of accessing the instance
12. The Singleton Pattern II Benefits: Controlled access to sole instance (or multiple instances) Avoids “global variables” in namespace Permits Subclassing More flexible than static member and methods
13. Abstract Factory (Kit) I Provide an interface for creating families of related or dependent object without specifying their concrete classes Used to de-couple clients from a particular concrete implementation Example: Different implementations of handling an order’s costs (e.g. TaxCalculator(EU,USA, CN,etc), shipping costs, etc)
15. Abstract Factory (Kit) III Use the Abstract Factory pattern when a system should be independent of how its products are created, composed, and represented. a system should be configured with one of multiple families of products. a family of related product objects is designed to be used together, and you need to enforce this constraint. you want to provide a class library of products, and you want to reveal just their interfaces, not their implementations.
16. Abstract Factory (Kit) IV Benefits: Isolates concrete classes Allows to change product family easily Promotes consistency among products Factory usually a Singleton; ideally create<Object> should have a type parameter to make it extensible
17. Structural Patterns In this section, we’ll discuss the following patterns Adapter (or Wrapper) Pattern Bridge Pattern Composite Pattern Decorator Pattern Façade Pattern
18. Adapter (Wrapper) I Convert the interface of a class into another interface clients expect. Adapter lets classes work together that couldn't otherwise because of incompatible interfaces. Example Merging a new library with an old library you discover two methods with the same name but different parameters
19. Adapter (Wrapper) II Benefits: Allow two or more incompatible objects to communicate and interact. Improves reusability of older functionality.
20. Adapter (Wrapper) III Use when: When you want to use an existing class, and its interface does not match the interface you need. When you want to create a reusable class that cooperates with unrelated or onforeseen classes, classes that don't necessarily have compatible interfaces. When you want to use an object in an environment that expects an interface that is diferent from the object's interface. When you must ensure interface translation among multiple sources.
21. Bridge (Handle) Pattern I Used to decouple an abstraction from its implementation so that the two can vary independently When an abstraction (abstract class) can have several implementations, the usual way to accommodate them is to use inheritance This isn’t always a flexible approach because the implementation binds to the abstraction permanently Use the pattern when: You want to avoid a permanent binding between an abstraction and its implementation Both the abstractions and the implementations should be extensible by sub-classing Changes in the implementation of an abstraction should not impact clients
22. Bridge (Handle) Pattern II Use the pattern when (cont): You have a class hierarchy that proliferates because it needs to adapt to various specific implementations You want to share an implementation among multiple objects but you want to keep the fact hidden from the client.
23. Bridge (Handle) Pattern III Known uses GUI frameworks as discussed previously. Persistence Frameworks Consequences: Implementation is not bound permanently to an interface Eliminates compile time dependencies (no recompilation of abstract class) Decoupling encourages layering, therefore a better structured system Improved extensibility Hiding implementation details from clients
24. Composite pattern I Used to compose objects into tree structures to represent part-whole hierarchies. Clients treat individual objects and compositions of objects uniformly Example Consider graphics applications that allow users to build complex diagrams out of simple components which can be grouped into more complex ones A simple implementation would define classes for graphical primitives and other classes that act as containers for these primitives Problem: code using these classes must treat primitives and objects differently The distinction increases the complexity of the system The pattern uses recursive composition so clients do not make this distinction
25. Composite pattern II Use the pattern when: You want to represent part-whole hierarchies of objects You want clients to be able to ignore differences between compositions of objects and individual objects
26. Composite pattern III Example Consequences Define class hierarchies consisting of primitive objects and composite objects Simplifies the client’s architecture Simplifies the process of adding new components The design can be overly general (disadvantage)
27. Decorator (WRAPPER) Pattern I Decorator is used to attach responsibilities to an object dynamically Decorators provide a flexible alternative to sub-classing for extending functionality Why use it? We use it when we need to add responsibilities to individual objects, not the entire class (e.g. adding borders or scrollbars to a visual widget) If you use inheritance will affect every instance which will not allow it to vary the choice as it is statically linked The solution is to add the object, called the decorator or wrapper, within another that adds the required property
28. Decorator (WRAPPER) Pattern II Use the Decorator To add responsibilities to individual objects dynamically and transparently To withdraw responsibilities from the object When extending by sub-classing is impractical or not permitted A large number of independent extensions would result in an explosion of classes A class definition may be hidden or sealed (final)
29. Decorator (WRAPPER) Pattern III Consequences More flexible than static inheritance Easier to add a property twice (e.g. a widget with a double border) Avoids feature-laden classes up in the hierarchy, reducing complexity. Features are added incrementally with new decorator objects The decorator and its component are identical, the decorator is a transparent enclosure similar to a photograph frame Lots of little objects (disadvantage), difficult to learn and debug Used frequently in UI Toolkits and in the implementation of IO stream classes
30. Façade Pattern I Provides a unified interface to a set of interfaces in a subsystem Defines a higher level interface that makes the subsystem easier to use Structuring a system into subsystems helps reduce complexity Common design goal is to minimise communication and dependency between subsystems Façade objects provides a single, simplified interface to more general facilities of the sub-system
31. Façade Pattern II Example: Programming environment providing access to its compiler subsystem Higher level interface shields clients from intricate details of different parts of compiler by allowing access to specific functionality of different subparts Use Façade when: Provide a simple interface to a complex system There are many dependencies between clients and the implementation classes of an abstraction – Façade decouples the sub-system from clients Layer your subsystems. Façade defines the entry to each subsystem layer
32. Façade Pattern III Consequences Shields clients from sub-system components Promotes weak coupling between sub-system and its clients Reduces compilation dependencies Does not prevent applications from using subsystem classes if they need to
33. Behavioural Patterns These are some common behavioural patterns: Iterator Pattern Observer Pattern Strategy Pattern
34. Iterator (Cursor) Pattern I Provides a way to access the elements of an aggregate object sequentially without exposing its underlying representation An aggregate object (e.g. List) should give you a way to access its elements without exposing its structure You might want to traverse the list in many ways, but you want to keep the design and implementation of the List clean The idea of the pattern is to take the responsibility for accessing and traversing the list using at iterator object The iterator keeps track of the current element The List is responsible for creating its own iterator, possibly using a Factory to generalise the operation
35. Iterator (Cursor) Pattern II Use this pattern when you want To access an aggregate object’s contents without exposing its internal representation Support multiple traversals of aggregate objects Provide a uniform interface for traversing different aggregate structures
36. Iterator (Cursor) Pattern III Consequences of using this pattern Supports variations in the traversal of an aggregate Simplify the aggregate interface Mode than one traversal can be pending on the same aggregate Known uses: Collection classes (Lists, Vectors, etc)
37. Observer (dependents) Pattern I Defines a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically When partitioning a system into a collection of cooperating classes, one needs to maintain consistency between related objects Note that tightly coupling class is not a solution because it reduces reusability The observer pattern describes how to establish common relationships between objects The key objects are the subject and the observer All observer are notified when the subject changes (publish-subscribe model)
38. Observer (dependents) Pattern II Used when Abstraction has two aspects, one dependent on the other. Encapsulate the objects separately and reuse them independently When a change to one object requires changing the others, and you do not know how many objects to change When an object needs to be able to notify other objects without making assumptions about who these objects are (not tightly coupled)
39. Observer (dependents) Pattern III Consequences Abstract coupling between Subject and Observer. Subject knows that it has a list of observers conforming to the observer interface, it does not know the concrete class of the observer – minimal coupling Support for broadcast communication Unexpected updated (disadvantage). Since observers have no knowledge of other observers, changing the subject might result in undesired updates
40. Strategy (Policy) Pattern I Define a family of algorithms that encapsulate one another and make them interchangeable Strategy lets the algorithm vary independently of the client that uses them Example: Many algorithms exist for breaking a stream of text into lines. Hard-wiring all algorithms into the classes that require them is not desirable because Client get overly complex Different algorithms will be appropriate at different times Difficult to add new algorithms and vary existing ones
41. Strategy (Policy) Pattern II Use this pattern when Many related classes differ only in their behaviour Need different variants of an algorithm An algorithm uses data that clients shouldn’t know about (avoid exposing complex, algorithm-specific data structures) A class defines many behaviours that appear as multiple conditional statements in its operators
42. Strategy (Policy) Pattern III Consequences Families of related algorithms. Hierarchies of Strategy classes define a family of algorithms that can be reused An alternative to sub-classing, which is easier to switch to, understand and extend Strategies eliminate conditional statements Provides a choice of implementations Clients must be aware of different strategies (disadvantage) Communication overhead between Strategy and Context (Strategy interface is shared, so some simple concrete classes may use little or none of the parameters passes to them. Tightly couple context and strategy to solve this problem) Increased number of objects
43. Other Model-View-Controller (MVC) This pattern isolates domain logic from the user interface The model manages the behaviour and data of the application domain, The view renders the model into a form suitable for interaction, typically a user interface element. The controller receives input and initiates a response by making calls on model objects. A controller accepts input from the user and instructs the model and viewport to perform actions based on that input. Sometimes considered a framework
44. Further Reading Gamma, E., Helm, R., Johnson, R., & Vlissides, J. (2007). Design Patterns: Elements of Reusable Object-Oriented Software. USA: Addison-Wesley Professional (ISBN 0-201-63361-2) McConell, S. (2004). Code Complete: A Practical Handbook of Software Construction. USA: MICROSOFT PRESS (ISBN 0-735-61967-0) Alur, D., Malks, D., & Crupi, J. (2003). Core J2EE Patterns: Best Practices and Design Strategies. USA: Prentice Hall (ISBN 0-131-42246-4) http://www.dofactory.com/Patterns/Patterns.aspx http://www.oodesign.com
Editor's Notes
Code is platform-dependent. Concrete classes here have a specific implementation
Widgets with all possible types of borders, scrollbars, etc.
Widgets with all possible types of borders, scrollbars, etc.