Tài liệu Module 3: Logical Design and Behavioral Design Patterns doc

Contents Overview 1 Introduction to Behavioral Design Patterns 2 ATM Scenario 8 Relevant Behavior Patterns 13 Best Practices 20 Lab 3: Logical Design and Behavioral Design Patterns 21 Review 24 Module 3: Logical Design and Behavioral Design Patterns Information in this document is subject to change without notice. The names of companies, products, people, characters, and/or data mentioned herein are fictitious and are in no way intended to represent any real individual, company, product, or event, unless otherwise noted. Complying with all applicable copyright laws is the responsibility of the user. No part of this document may be reproduced or transmitted in any form or by any means, electronic or mechanical, for any purpose, without the express written permission of Microsoft Corporation. If, however, your only means of access is electronic, permission to print one copy is hereby granted. Microsoft may have patents, patent applications, trademarks, copyrights, or other intellectual property rights covering subject matter in this document. Except as expressly provided in any written license agreement from Microsoft, the furnishing of this document does not give you any license to these patents, trademarks, copyrights, or other intellectual property.  2000 Microsoft Corporation. All rights reserved. Microsoft, Active Directory, ActiveX, BackOffice, FrontPage, Microsoft Press, MSDN, MS-DOS, PowerPoint, Visio, Visual Basic, Visual C++, Visual InterDev, Visual J++, Visual Studio, Win32, Windows, and Windows NT are either registered trademarks or trademarks of Microsoft Corporation in the U.S.A. and/or other countries. Other product and company names mentioned herein may be the trademarks of their respective owners. Program Managers: Rhy Mednick, Susie Parrent Instructional Designer: Susie Parrent Subject Matter Experts: David Chesnut, Sam Gill (TechnoWiz), Michel Pahud Media Management: David Mahlmann Editing Manager: Lynette Skinner Editor: Mick Alberts, Jennifer Linn Production Manager: Miracle Davis Print Coordinators: Linda Lu Cannon (Write Stuff), Marlene Lambert (Online Training Solutions, Inc.) Build Coordinator: Eric Wagoner Graphic Artist: Scott Serna Test Lead: Eric Myers Manufacturing Manager: John Williams Group Product Manager: Juan Fernando Rivera Lead Product Manager, System Services and Infrastructure: Edward Dudenhoefer Manufacturing Manager: Rick Terek Operations Coordinator: John Williams Manufacturing Support: Laura King; Kathy Hershey Lead Product Manager, Release Management: Bo Galford Group Manager, Courseware Infrastructure: David Bramble General Manager: Robert Stewart Module 3: Logical Design and Behavioral Design Patterns iii Instructor Notes This module provides students with knowledge about how to use behavioral design patterns in the transition from conceptual to logical design. Students will also learn how to apply this knowledge to a sample application: an Automated Teller Machine (ATM). After completing this module, students will be able to: ! Describe behavioral design patterns. ! Identify the appropriate architecture template for a given set of use cases. ! Describe how an ATM application can take advantage of behavioral design patterns. Materials and Preparation This section provides the materials and preparation tasks that you need to teach this module. Required Materials To teach this module, you need the following materials: ! Microsoft ® PowerPoint ® file 1910A_03.ppt ! Module 3: Logical Design and Behavioral Design Patterns ! Lab 3: Logical Design and Behavioral Design Patterns Preparation Tasks To prepare for this module, you should: ! Read all of the materials for this module. ! Complete the lab. Presentation: 60 Minutes Lab: 30 Minutes iv Module 3: Logical Design and Behavioral Design Patterns Module Strategy Use the following strategy to present this module: ! Introduction to Behavioral Design Patterns The purpose of this section is to introduce students to behavioral design patterns and their use in the logical design. It is important to emphasize which design patterns are discovered in order to simplify the task of creating a logical design and to provide consistency. Patterns are not limited to those that have been published in the design pattern literature. New patterns are being added all the time. For examples, refer to William Stamatakis’ book Microsoft Visual Basic Design Patterns, Microsoft Press®, 2000. In the topic “Interaction with Users or Other Systems,” focus on the step of discovering design patterns that are associated with the facade, the business logic, and the data access layer (DAL). Emphasize that although the discovery of design patterns is an art, there is a need to formalize the patterns discovered to allow for their correct use. Note that this course is not recommending a methodology or process for creating logical and physical designs. For ease of learning, the layers are presented from the front of a system to the back (user services to data services). This is not necessarily the order in which you would actually perform design work. Also, you probably would not derive the entire logical design and then the physical design, as implied by the labs in this course. For learning purposes, that is the order of the labs. In reality, you will probably perform iterations over the logical and physical designs. ! ATM Scenario The purpose of this section is to introduce students to the logical design process by using a simple example of an ATM. The purpose of this example is to illustrate how common behavioral design patterns are identified. The section allows you to present a statement of the ATM problem, present the ATM use cases, identify the architecture template for an ATM application, and review the sequence diagram of an ATM object model. ! Relevant Behavior Patterns The purpose of this section is to present three behavioral design patterns that might be useful in the logical design of an application: State, Authentication, and Queue. Refer students to Appendix B, “Additional Design Patterns Used in Market Purchasing,” for a formal description of Authentication and Queue. ! Best Practices Discovering common behavioral patterns in an application is an important logical design validation step. It confirms that the design is based on recurrent themes. Module 3: Logical Design and Behavioral Design Patterns v Lab Strategy ! Lab 3: Logical Design and Behavioral Design Patterns The purpose of Lab 3 is for students to learn how to apply behavioral design patterns. Students will probably not derive the exact same answers as the lab answers. This is acceptable as long as the student answers are justified and reflect the principles discussed in the module. Discuss with students their answers to Lab 3. Module 3: Logical Design and Behavioral Design Patterns 1 # ## # Overview ! Introduction to Behavioral Design Patterns ! ATM Scenario ! Relevant Behavior Patterns ! Best Practices In this module, you will learn about using behavioral design patterns in the transition from conceptual to logical design. You will also learn how to apply this knowledge to a sample application: an Automated Teller Machine (ATM). After completing this module, you will be able to: ! Describe behavioral design patterns. ! Identify the appropriate architecture template for a given set of use cases. ! Describe how an ATM application can take advantage of behavioral design patterns. Topic Objective To provide an overview of the module topics and objectives. Lead-in In this module, you will learn about behavioral design patterns. 2 Module 3: Logical Design and Behavioral Design Patterns # ## # Introduction to Behavioral Design Patterns ! The Problem ! Interaction with Users or Other Systems ! Maintaining Business Rules ! Data Store Behavioral design patterns represent behavior that can be translated into common algorithms and assignments of responsibilities between objects. They describe not only common activities that objects perform, but also common patterns of communication between objects. In this section, the following topics will be covered: ! The problem ! Interaction with users or other systems ! Maintaining business rules ! Data store Topic Objective To provide an overview of the section topics and objectives. Lead-in In this section, you will learn about behavioral design patterns. Module 3: Logical Design and Behavioral Design Patterns 3 The Problem ! Interactions ! Rules ! Data Store An enterprise application can be characterized in terms of its three main activities: its interaction with its users and other applications, its responsibility for maintaining business rules and integrity, and its responsibility for recording and storing a chronology of events. Enterprise applications, while they might differ in their purpose, are architecturally similar, as was shown in Module 2, “Architecture and Structural Design Patterns.” Similarly, enterprise objects that represent different entities within an enterprise have many things in common. In particular, they share similar behavior. The purpose of behavioral pattern design is to identify common patterns for interaction with users and other systems, for maintaining business rules, and for storing data. Discovering useful patterns and using them in the logical design of objects is an art. The approach being prescribed for the logical design in object-oriented analysis and design is to first identify the architecture template, to then identify the enterprise objects that belong to each of the architecture template layers, and to finally identify the behavioral design pattern for each of the enterprise objects. The goal for this approach is to use in a design as many common elements as possible. An excellent logical design presents the correct mix of an architectural template, objects, and object behavioral patterns. Because it is impossible to identify all of the pieces (the architecture, objects, and object behavioral patterns) simultaneously, the problem is partitioned into first identifying the architecture template, then identifying the objects, and finally identifying the behavioral design patterns applicable for each object. Topic Objective To provide a background of the behavioral design pattern problem. Lead-in In this slide, you will learn about the problem facing application designers that necessitates behavioral design patterns. 4 Module 3: Logical Design and Behavioral Design Patterns Interaction with Users or Other Systems ! Interaction with Users ! Interaction with Other Systems If you think about the kind of behavior that is involved in user interaction or interaction with other systems, you will realize that there are some common behavioral design patterns. Interaction with Users For interaction with users, you could consider the following behavioral design patterns: ! Command Command is a behavioral design pattern that represents requests as objects, thereby allowing objects to be separate from the commands they execute. For example, a toolkit may provide user interface elements such as buttons and menu items. However, the toolkit cannot possibly know the actions with which a user will connect those elements. A Button class will likely perform many different functions in the same application. How will it call the correct function when pressed? The Command pattern allows an appropriate concrete command class to be associated with user interface elements at run time. When the button is pressed, it calls the Command object with which it was initialized. ! Memento Memento is a behavioral design pattern that captures and externalizes an object’s internal state. An example of using a Memento occurs when a user logs on, and the state of the application at the time they logged on previously is restored. This state is then exposed to all of the other objects in the application. Topic Objective To provide a background about interaction with users and other systems. Lead-in In this topic, you will learn how to identify common behavioral design patterns in interaction with users and other systems. [...]... the logical design Module 3: Logical Design and Behavioral Design Patterns 21 Lab 3: Logical Design and Behavioral Design Patterns Topic Objective To introduce the lab Lead-in In this lab, you will evaluate a set of use cases and determine which behavioral design patterns apply to them Explain the lab objectives Objectives After completing this lab, you will be able to: ! Choose behavioral patterns and. .. updated and extended easily without breaking dependencies in functions or other objects Estimated time to complete this lab: 30 minutes 22 Module 3: Logical Design and Behavioral Design Patterns Exercise 1 Using Behavioral Design Patterns In this exercise, you will evaluate a set of use cases and determine which behavioral design patterns apply to them ! Evaluate the conceptual design for behavioral patterns. .. section, the relevant behavioral design patterns that are applicable to the ATM system will be presented This section will cover the following topics: ! Behavioral design pattern in the ATM system: State ! Extended design pattern in the ATM system: Authentication ! Extended design pattern in the ATM system: Queue 13 14 Module 3: Logical Design and Behavioral Design Patterns Behavioral Design Pattern in... user selected 16 Module 3: Logical Design and Behavioral Design Patterns Behavioral Design Pattern in the ATM System: Authentication Topic Objective To provide an explanation of how the ATM system uses the Authentication design pattern Authenticator +Login() +CheckAccess() Lead-in In this topic, you will learn how the Authentication behavioral design pattern is used in the logical design of the ATM... Queue behavioral design pattern in the design patterns literature The Queue behavioral pattern was discovered during the development of this course and the accompanying Market Purchasing application The Queue behavioral design pattern is described in detail in Appendix B: “Additional Design Patterns used in Market Purchasing.” Design patterns are not limited to the patterns that are formalized in the design. .. 20 Module 3: Logical Design and Behavioral Design Patterns Best Practices Topic Objective To provide a discussion of the best practices for using behavioral design patterns ! Understand Use Cases Before Locking into Behavior Pattern ! Create a Pattern If You Cannot Find One ! Hold Many Design Reviews Lead-in In this topic, you will learn the three best practices for behavioral design patterns Best.. .Module 3: Logical Design and Behavioral Design Patterns Interaction with Other Systems For interaction with other systems, you might consider using a Queue behavioral design pattern Queue is a behavioral design pattern that defines a many-to-many dependency between objects so that one or more objects post messages to a message queue and all of their dependents can retrieve... the section topics and objectives ! ! In this section, you will learn about the relevant behavioral design patterns for the ATM system Extended Design Pattern in the ATM System: Authentication ! Lead-in Behavioral Design Pattern in the ATM System: State Extended Design Pattern in the ATM System: Queue The last task in a logical design is to identify the relevant behavioral design patterns applicable... them to a logical design, based on a given use case Prerequisites Before working on this lab, you must: ! Complete Module 3, Logical Design and Behavioral Design Patterns. ” ! Complete Lab 2, “Architecture and Structural Design Patterns. ” Scenario Many use cases that involve working with a requisition have been identified For example, the Submit Requisition use case must save a requisition and mark... logical design of the ATM system Client -Token Resource +Handle() There are two other behavioral design patterns that can be used in the logical design of an ATM system Both of these design patterns are extended design patterns, which means that they are not part of the currently published formal design pattern literature One of these design patterns is Authentication Pattern element Description Pattern . about behavioral design patterns. 2 Module 3: Logical Design and Behavioral Design Patterns # ## # Introduction to Behavioral Design Patterns ! The Problem. topics and objectives. Lead-in In this section, you will learn about behavioral design patterns. Module 3: Logical Design and Behavioral Design Patterns