Java Design Patterns 101 Skill Level: Introductory
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Patterns Senior Member of Technical Staff and Pattern Languages Knowledge Systems Corp
Kyle Brown An Introduction to Patterns Senior Member of Technical Staff and Pattern Languages Knowledge Systems Corp. 4001 Weston Parkway CSC591O Cary, North Carolina 27513-2303 April 7-9, 1997 919-481-4000 Raleigh, NC [email protected] http://www.ksccary.com Copyright (C) 1996, Kyle Brown, Bobby Woolf, and 1 2 Knowledge Systems Corp. All rights reserved. Overview Bobby Woolf Senior Member of Technical Staff O Patterns Knowledge Systems Corp. O Software Patterns 4001 Weston Parkway O Design Patterns Cary, North Carolina 27513-2303 O Architectural Patterns 919-481-4000 O Pattern Catalogs [email protected] O Pattern Languages http://www.ksccary.com 3 4 Patterns -- Why? Patterns -- Why? !@#$ O Learning software development is hard » Lots of new concepts O Must be some way to » Hard to distinguish good communicate better ideas from bad ones » Allow us to concentrate O Languages and on the problem frameworks are very O Patterns can provide the complex answer » Too much to explain » Much of their structure is incidental to our problem 5 6 Patterns -- What? Patterns -- Parts O Patterns are made up of four main parts O What is a pattern? » Title -- the name of the pattern » A solution to a problem in a context » Problem -- a statement of what the pattern solves » A structured way of representing design » Context -- a discussion of the constraints and information in prose and diagrams forces on the problem »A way of communicating design information from an expert to a novice » Solution -- a description of how to solve the problem » Generative: -
Iot Design Patterns: Computational Constructs to Design, Build and Engineer Edge Applications
2016 IEEE First International Conference on Internet-of-Things Design and Implementation IoT Design Patterns: Computational Constructs to Design, Build and Engineer Edge Applications Soheil Qanbari∗, Samim Pezeshki†, Rozita Raisi †, Samira Mahdizadeh∗, Rabee Rahimzadeh†, Negar Behinaein†, Fada Mahmoudi†, Shiva Ayoubzadeh †, Parham Fazlali†, Keyvan Roshani†, Azalia Yaghini†, Mozhdeh Amiri†, Ashkan Farivarmoheb†, Arash Zamani†, and Schahram Dustdar∗ ∗Distributed Systems Group, Vienna University of Technology, Vienna, Austria {qanbari, dustdar}@dsg.tuwien.ac.at †Baha’i Institute for Higher Education (BIHE) {firstname.lastname}@bihe.org Abstract—The objective of design patterns is to make design wiring approach of Hanmer [7]. This articulates the benefits robust and to abstract reusable solutions behind expressive of applying patterns by showing how each piece can fit into interfaces, independent of a concrete platform. They are ab- one integrated solution. stracted away from the complexity of underlying and enabling technologies. The connected things in IoT tend to be diverse With this motivation in mind, the paper continues in Sec- in terms of supported protocols, communication methods and tion II, with a brief review of how IoT design patterns are capabilities, computational power and storage. This motivates documented. Next, we introduce the diversity of our proposed us to look for more cost-effective and less resource-intensive patterns and how they are related to the edge applications IoT microservice models. We have identified a wide range of life-cycle in Section III. With some definitive clues on the design disciplines involved in creating IoT systems, that act as a seamless interface for collaborating heterogeneous things, and pattern language convention, we propose an edge provisioning suitable to be implemented on resource-constrained devices. -
Structured Patterns Metamodel Standardtm Publication
An OMG® Structured Patterns Metamodel StandardTM Publication OBJECT MANAGEMENT GROUP Structured Patterns Metamodel StandardTM V1.1 _______________________________________________ OMG Document Number: formal/2017-04-05 Release Date: July 2017 Standard document URL: http://www.omg.org/spec/SPMS/1.1 Normative Machine Consumable File(s): http://www.omg.org/spec/ SPMS /201 60301 /SPMS.xmi http://www.omg.org/spec/ SPMS/20160301/PHORML.xml http://www.omg.org/spec/ SPMS /201 60301 /APML.xmi _________________________________________________ Copyright © 2017, Object Management Group, Inc. Copyright © 2014, The Software Revolution, Inc. Copyright © 2014, CAST Copyright © 2014, KDM Analytics Copyright © 2014, Benchmark Consulting Copyright © 2014, eCube Systems Copyright © 2014, MITRE Copyright © 2014, University of North Carolina at Chapel Hill Copyright © 2014, École Polytechnique de Montréal USE OF SPECIFICATION – TERMS, CONDITIONS & NOTICES The material in this document details an Object Management Group specification in accordance with the terms, conditions and notices set forth below. This document does not represent a commitment to implement any portion of this specification in any company's products. The information contained in this document is subject to change without notice. LICENSES The companies listed above have granted to the Object Management Group, Inc. (OMG) a nonexclusive, royalty-free, paid up, worldwide license to copy and distribute this document and to modify this document and distribute copies of the modified version. Each of the copyright holders listed above has agreed that no person shall be deemed to have infringed the copyright in the included material of any such copyright holder by reason of having used the specification set forth herein or having conformed any computer software to the specification. -
Research Challenges in Nextgen Service Orchestration
Research Challenges in Nextgen Service Orchestration Luis M. Vaquero1, Felix Cuadrado2, Yehia Elkhatib3, Jorge Bernal-Bernabe4, Satish N. Srirama5, and Mohamed Faten Zhani6 1Faculty of Engineering, University of Bristol, UK Corresponding author: [email protected] 2EECS, Queen Mary University of London, UK 3MetaLab, SCC, Lancaster University, UK 4DIIC, University of Murcia, Spain 5Institute of Computer Science, University of Tartu, Estonia 6École de Technologie Supérieure, Montréal Abstract Fog/edge computing, function as a service, and programmable infrastructures, like software-defined networking or network function virtualisation, are becoming ubiquitously used in modern Information Technology infrastructures. These technologies change the characteristics and capabilities of the underlying computational substrate where services run (e.g. higher volatility, scarcer computational power, or programmability). As a consequence, the nature of the services that can be run on them changes too (smaller codebases, more fragmented state, etc.). These changes bring new requirements for service orchestrators, which need to evolve so as to support new scenarios where a close interaction between service and infrastructure becomes essential to deliver a seamless user experience. Here, we present the challenges brought forward by this new breed of technologies and where current orchestration techniques stand with regards to the new challenges. We also present a set of promising technologies that can help tame this brave new world. Keywords: NVM; SDN; NFV; orchestration; large scale; serverless; FaaS; churn; edge; fog. 1. Introduction arXiv:1806.00764v2 [cs.DC] 7 Jun 2018 There is a new breed of technologies that are becoming mainstream in current Information Technology (IT) infrastructures. Fog computing aims to partially move services from core cloud data centres into the edge of the network [159]. -
Design Patterns in PHP and Laravel — Kelt Dockins Design Patterns in PHP and Laravel
Design Patterns in PHP and Laravel — Kelt Dockins Design Patterns in PHP and Laravel Kelt Dockins [email protected] Design Patterns in PHP and Laravel Kelt Dockins Dolph, Arkansas USA ISBN-13 (pbk): 978-1-4842-2450-2 ISBN-13 (electronic): 978-1-4842-2451-9 DOI 10.1007/978-1-4842-2451-9 Library of Congress Control Number: 2016961807 Copyright © 2017 by Kelt Dockins This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. Trademarked names, logos, and images may appear in this book. Rather than use a trademark symbol with every occurrence of a trademarked name, logo, or image we use the names, logos, and images only in an editorial fashion and to the benefit of the trademark owner, with no intention of infringement of the trademark. The use in this publication of trade names, trademarks, service marks, and similar terms, even if they are not identified as such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights. While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. -
Process Synchronisation Background (1)
Process Synchronisation Background (1) Concurrent access to shared data may result in data inconsistency Maintaining data consistency requires mechanisms to ensure the orderly execution of cooperating processes Producer Consumer Background (2) Race condition count++ could be implemented as register1 = count register1 = register1 + 1 count = register1 count- - could be implemented as register2 = count register2 = register2 - 1 count = register2 Consider this execution interleaving with ―count = 5‖ initially: S0: producer execute register1 = count {register1 = 5} S1: producer execute register1 = register1 + 1 {register1 = 6} S2: consumer execute register2 = count {register2 = 5} S3: consumer execute register2 = register2 - 1 {register2 = 4} S4: producer execute count = register1 {count = 6 } S5: consumer execute count = register2 {count = 4} Solution: ensure that only one process at a time can manipulate variable count Avoid interference between changes Critical Section Problem Critical section: a segment of code in which a process may be changing Process structure common variables ◦ Only one process is allowed to be executing in its critical section at any moment in time Critical section problem: design a protocol for process cooperation Requirements for a solution ◦ Mutual exclusion ◦ Progress ◦ Bounded waiting No assumption can be made about the relative speed of processes Handling critical sections in OS ◦ Pre-emptive kernels (real-time programming, more responsive) Linux from 2.6, Solaris, IRIX ◦ Non-pre-emptive kernels (free from race conditions) Windows XP, Windows 2000, traditional UNIX kernel, Linux prior 2.6 Peterson’s Solution Two process solution Process Pi ◦ Mutual exclusion is preserved? ◦ The progress requirements is satisfied? ◦ The bounded-waiting requirement is met? Assumption: LOAD and STORE instructions are atomic, i.e. -
The Culture of Patterns
UDC 681.3.06 The Culture of Patterns James O. Coplien Vloebergh Professor of Computer Science, Vrije Universiteit Brussel, PO Box 4557, Wheaton, IL 60189-4557 USA [email protected] Abstract. The pattern community came about from a consciously crafted culture, a culture that has persisted, grown, and arguably thrived for a decade. The culture was built on a small number of explicit principles. The culture became embodied in its activities conferences called PLoPs that centered on a social activity for reviewing technical worksand in a body of literature that has wielded broad influence on software design. Embedded within the larger culture of software development, the pattern culture has enjoyed broad influence on software development worldwide. The culture hasnt been without its problems: conflict with academic culture, accusations of cultism, and compromises with other cultures. However, its culturally rich principles still live on both in the original organs of the pattern community and in the activities of many other software communities worldwide. 1. Introduction One doesnt read many papers on culture in the software literature. You might ask why anyone in software would think that culture is important enough that an article about culture would appear in such a journal, and you might even ask yourself: just what is culture, anyhow? The software pattern community has long taken culture as a primary concern and focus. Astute observers of the pattern community note a cultural tone to the conferences and literature of the discipline, but probably view it as a distant and puzzling phenomenon. Casual users of the pattern form may not even be aware of the cultural focus or, if they are, may discount it as a distraction. -
Dependency Injection in Unity3d
Dependency Injection in Unity3D Niko Parviainen Bachelor’s thesis March 2017 Technology, communication and transport Degree Programme in Software Engineering Description Author(s) Type of publication Date Parviainen, Niko Bachelor’s thesis March 2017 Language of publication: English Number of pages Permission for web publi- 57 cation: x Title of publication Dependency Injection in Unity3D Degree programme Degree Programme in Software Engineering Supervisor(s) Rantala, Ari Hämäläinen, Raija Assigned by Psyon Games Oy Abstract The objective was to find out how software design patterns and principles are applied to game development to achieve modular design. The tasks of the research were to identify the dependency management problem of a modular design, find out what the solutions offered by Unity3D are, find out what the dependency injection pattern is and how it is used in Unity3D environment. Dependency management in Unity3D and the dependency injection pattern were studied. Problems created by Unity3D’s solutions were introduced with examples. Dependency in- jection pattern was introduced with examples and demonstrated by implementing an ex- ample game using one of the available third-party frameworks. The aim of the example game was to clarify if the use of dependency injection brings modularity in Unity3D envi- ronment and what the cost of using it is. The principles of SOLID were introduced with generic examples and used to assist depend- ency injection to further increase the modularity by bringing the focus on class design. Dependency injection with the help of SOLID principles increased the modularity by loosely coupling classes even though slightly increasing the overall complexity of the architecture. -
Singleton Pattern: Motivation • Sometimes Need an Object That Is Unique – There Will Only Be a Single Instance of the Class
Singleton Pattern: Motivation • Sometimes need an object that is unique { There will only be a single instance of the class • Could be done with a global variable, BUT { Such an instance would exist for the duration of the program { If the instance were resource-intensive, this could be a problem { It would be better to create such an object only on an as-needed basis 1 Singleton Pattern: Defined • Singleton Pattern (177): Ensures a class has only one instance, and provides a global point of access to it. • The class manages a single instance of itself. • No other classes can create an instance of a singleton on their own. { I.e., another class cannot execute newInstance = new SingletonClass() • The singleton provides the means for other classes to access the instance. • Class diagram: • The question is: How to implement this so that we can insure that no more than one instance can be created? 2 Singleton Pattern: Implementation • We know that if we have a public constructor for a class, instances can be created by any other classes • But if we make the constructor private, only objects of the class could call the constructor, but then how could a first object of the class be created? { I.e., The only way to create an object of the class is to already have an object of the class (chicken and egg problem) • The trick is to have a private constructor but a static method that creates instances of the class { Since we're dealing with a singleton, the static method will include code that insures that only a single instance of the class will be created • Sample code: public class Singleton { private static Singleton uniqueInstance; private Singleton() { } public static Singleton getInstance() { if (uniqueInstance == null) uniqueInstance = new Singleton(); return uniqueInstance; } .. -
Designpatternsphp Documentation Release 1.0
DesignPatternsPHP Documentation Release 1.0 Dominik Liebler and contributors Jul 18, 2021 Contents 1 Patterns 3 1.1 Creational................................................3 1.1.1 Abstract Factory........................................3 1.1.2 Builder.............................................8 1.1.3 Factory Method......................................... 13 1.1.4 Pool............................................... 18 1.1.5 Prototype............................................ 21 1.1.6 Simple Factory......................................... 24 1.1.7 Singleton............................................ 26 1.1.8 Static Factory.......................................... 28 1.2 Structural................................................. 30 1.2.1 Adapter / Wrapper....................................... 31 1.2.2 Bridge.............................................. 35 1.2.3 Composite............................................ 39 1.2.4 Data Mapper.......................................... 42 1.2.5 Decorator............................................ 46 1.2.6 Dependency Injection...................................... 50 1.2.7 Facade.............................................. 53 1.2.8 Fluent Interface......................................... 56 1.2.9 Flyweight............................................ 59 1.2.10 Proxy.............................................. 62 1.2.11 Registry............................................. 66 1.3 Behavioral................................................ 69 1.3.1 Chain Of Responsibilities................................... -
Developing with Pojos: Faster and Easier 3 Chapter 2 ■ J2EE Design Decisions 31
FROM OUR PEER REVIEW ... “Chris Richardson targets critical design issues for lightweight Java enterprise applications using POJOs with fantastic in-depth exam- ples. This book extends Martin Fowler’s great book, Enterprise Architecture Patterns, as well as the more recent Domain-Driven Design by Eric Evans, by providing practical design guidance and useful examples. It also addresses the architecture and design issues asso- ciated with Spring and Hibernate development, whereas Man- ning’s companion ‘in Action’ books focus primarily on the Spring and Hibernate technologies. “This is a powerful book for architects, senior developers, and consultants. It uniquely combines best practices and design wisdom to integrate domain-driven design and test-driven development for object-oriented Java enterprise applications using lightweight Spring, Hibernate, and JDO technologies. “The table of contents reflects the important topics that most architects and enterprise developers face every day. There is signifi- cant need for a book like this, which shows how to address many common and complex design issues with real-world examples. The content in this book is unique and not really available elsewhere.” DOUG WARREN Software Architect Countrywide Financial “POJOs in Action fills a void: the need for a practical explanation of the techniques used at various levels for the successful building of J2EE projects. This book can be compared with the less enterprise- oriented and more abstract J2EE Development without EJB by Rod Johnson, but Richardson offers a step-by-step guide to a successful J2EE project. The explanations of the various alternatives available for each step provide the main thrust of this book. -
Lecture 26: Creational Patterns
Creational Patterns CSCI 4448/5448: Object-Oriented Analysis & Design Lecture 26 — 11/29/2012 © Kenneth M. Anderson, 2012 1 Goals of the Lecture • Cover material from Chapters 20-22 of the Textbook • Lessons from Design Patterns: Factories • Singleton Pattern • Object Pool Pattern • Also discuss • Builder Pattern • Lazy Instantiation © Kenneth M. Anderson, 2012 2 Pattern Classification • The Gang of Four classified patterns in three ways • The behavioral patterns are used to manage variation in behaviors (think Strategy pattern) • The structural patterns are useful to integrate existing code into new object-oriented designs (think Bridge) • The creational patterns are used to create objects • Abstract Factory, Builder, Factory Method, Prototype & Singleton © Kenneth M. Anderson, 2012 3 Factories & Their Role in OO Design • It is important to manage the creation of objects • Code that mixes object creation with the use of objects can become quickly non-cohesive • A system may have to deal with a variety of different contexts • with each context requiring a different set of objects • In design patterns, the context determines which concrete implementations need to be present © Kenneth M. Anderson, 2012 4 Factories & Their Role in OO Design • The code to determine the current context, and thus which objects to instantiate, can become complex • with many different conditional statements • If you mix this type of code with the use of the instantiated objects, your code becomes cluttered • often the use scenarios can happen in a few lines of code • if combined with creational code, the operational code gets buried behind the creational code © Kenneth M. Anderson, 2012 5 Factories provide Cohesion • The use of factories can address these issues • The conditional code can be hidden within them • pass in the parameters associated with the current context • and get back the objects you need for the situation • Then use those objects to get your work done • Factories concern themselves just with creation, letting your code focus on other things © Kenneth M.