Enterprise Rails docx

www.it-ebooks.info Download at Boykma.Com www.it-ebooks.info Enterprise Rails Download at Boykma.Com www.it-ebooks.info Other resources from O’Reilly Related titles Advanced Rails Ajax and Rails Learning Rails Learning Ruby Rails Cookbook  Rails: Up and Running Ruby Cookbook  The Ruby Programming Language oreilly.com oreilly.com is more than a complete catalog of O’Reilly books. You’ll also find links to news, events, articles, weblogs, sample chapters, and code examples. oreillynet.com is the essential portal for developers interested in open and emerging technologies, including new platforms, pro- gramming languages, and operating systems. Conferences O’Reilly brings diverse innovators together to nurture the ideas that spark revolutionary industries. We specialize in document- ing the latest tools and systems, translating the innovator’s knowledge into useful skills for those in the trenches. Visit conferences.oreilly.com for our upcoming events. Safari Bookshelf (safari.oreilly.com) is the premier online refer- ence library for programmers and IT professionals. Conduct searches across more than 1,000 books. Subscribers can zero in on answers to time-critical questions in a matter of seconds. Read the books on your Bookshelf from cover to cover or sim- ply flip to the page you need. Try it today for free. ,roadmap.14319 Page ii Friday, October 10, 2008 2:21 PM Download at Boykma.Com www.it-ebooks.info Enterprise Rails Dan Chak Beijing • Cambridge • Farnham • Köln • Sebastopol • Taipei • Tokyo Download at Boykma.Com www.it-ebooks.info Enterprise Rails by Dan Chak Copyright © 2009 Dan Chak. All rights reserved. Printed in the United States of America. Published by O’Reilly Media, Inc., 1005 Gravenstein Highway North, Sebastopol, CA 95472. O’Reilly books may be purchased for educational, business, or sales promotional use. Online editions are also available for most titles (http://safari.oreilly.com). For more information, contact our corporate/ institutional sales department: (800) 998-9938 or corporate@oreilly.com. Editor: Mike Loukides Production Editor: Loranah Dimant Copyeditor: Colleen Gorman Proofreader: Loranah Dimant Indexer: Joe Wizda Cover Designer: Karen Montgomery Interior Designer: David Futato Illustrator: Robert Romano Printing History: October 2008: First Edition. Nutshell Handbook, the Nutshell Handbook logo, and the O’Reilly logo are registered trademarks of O’Reilly Media, Inc. Enterprise Rails, the image of a sturgeon fish on the cover, and related trade dress are trademarks of O’Reilly Media, Inc. Many of the designations used by manufacturers and sellers to distinguish their products are claimed as trademarks. Where those designations appear in this book, and O’Reilly Media, Inc. was aware of a trademark claim, the designations have been printed in caps or initial caps. Java™ is a trademark of Sun Microsystems, Inc. While every precaution has been taken in the preparation of this book, the publisher and author assume no responsibility for errors or omissions, or for damages resulting from the use of the information con- tained herein. ISBN: 978-0-596-51520-1 [M] 1223662105 Download at Boykma.Com www.it-ebooks.info Table of Contents Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi 1. The Big Picture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 What Is Enterprise? 1 Growing Slowly 3 Understanding All the Pieces 5 Persistence Layer 5 Application Layer 8 Caching Layer 11 Messaging System 16 Web Server 16 Firewall 16 2. Organizing with Plugins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Benefits 20 Writing Your Own Plugins 21 Core Enhancements 22 Custom Extensions 26 Deployment 30 svn:externals 30 3. Organizing with Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Files and Directories 32 Module Boundaries for Namespacing 33 ActiveRecord Associations Between Modules 34 Reciprocal Relationships 35 Modules Presage Services 36 Ensuring Proper Load Order 38 Exercises 39 Refactor Steps 39 High-Level Module Refactor 39 Detangling Utility Methods 40 v Download at Boykma.Com www.it-ebooks.info 4. Database As a Fortress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Your Database Is an Application, Too 42 “One Framework to Rule Them All” 42 “No One in My Company Will Ever Write a Bug” 42 “This Rails Application Is the Only Application on Earth” 43 Sit Atop the Shoulders of Giants 43 Choosing the Right RDBMS 44 A Note on Migrations 44 Dispelling Myths 46 Operations and Reporting 47 5. Building a Solid Data Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 Theatre Tickets 51 Starting Simple 52 Constraints 54 Mythbusting 63 Referential Integrity 64 Intro to Indexing 70 6. Refactoring to Third Normal Form . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 Third Normal Form 73 Timing Is Key 77 Refactoring: Inheritance and Mixins 78 Exercises 82 Refactor Steps 82 7. Domain Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 Dealing with Zip Codes 87 Strategy Pattern with Domain Tables 89 Refactor from Day One 93 8. Composite Keys and Domain Key/Normal Form . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 Why Composite Natural Keys Matter 97 Spotting Composite Keys 99 Atop the Shoulders of… 101 Migrating to Domain Key/Normal Form 102 Using Composite Keys in Rails 105 Deferrable Foreign Key Constraints 109 Understanding the Trade-offs 111 Exercises 113 Refactor Steps 113 Single Column Refactor 114 vi | Table of Contents Download at Boykma.Com www.it-ebooks.info Multiple Column Refactor 115 9. Guaranteeing Complex Relationships with Triggers . . . . . . . . . . . . . . . . . . . . . . . . 117 Constraint Checking with Triggers 117 Anatomy of a PL/pgSQL Function 121 10. Multiple Table Inheritance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 The Problem 127 What Is Polymorphism? 129 Inheritance and Persistence 131 Single Table Inheritance 132 Multiple Table Inheritance 133 XOR on Columns 135 Elegant MTI in Rails 137 Factory Classes 143 Exercises 144 Refactor Steps 145 Refactoring STI 145 Refactoring: polymorphic => true 145 11. View-Backed Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 Database Views 148 Creating a View 149 Basing a Model on a View 149 Considerations 150 Insert, Update, Delete 151 References and Constraints 152 Indexing 153 Exercises 153 Refactor Steps 154 12. Materialized Views . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155 Materialized View Principles 156 A View to Materialize 157 Getting into Form 158 The Target Table 160 Refresh and Invalidation Functions 161 Time Dependency 163 Who Pays the Price? 165 Triggered Refreshes and Invalidations 168 Movie Showtimes 169 Hiding the Implementation with the Reconciler View 174 Periodic Refreshes 177 Table of Contents | vii Download at Boykma.Com www.it-ebooks.info Cache Indexes 178 Results 179 Cascading Caches 180 Exercises 180 13. SOA Primer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 What Is SOA? 183 Why SOA? 186 Shared Resources 187 Reduce Database Load 190 Scalability II: Caching Is Tricky 196 Reduce Local Complexity 197 In Summary 200 Exercises 200 14. SOA Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201 Service Considerations 201 Implementation Details Are Hidden 202 API Is Accessible 204 API Design Best Practices 205 Send Everything You Need 205 Limit Round Trips 207 Look for Opportunities for Parallelization 209 Send as Little as Possible 210 REST Versus XML-RPC Versus SOAP 212 XML-RPC 212 SOAP 214 15. An XML-RPC Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217 ActionWebService and Rails 2.0 217 Creating an Abstraction Barrier 218 ActiveRecord As the Physical Model Layer 218 The Object Model Layer 220 Defining the API 225 More Testing 230 The Client Plugin 232 Shared Code 234 The Client Singleton 234 Integration Testing 236 16. Refactoring to Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239 An Orders Service 239 Integrating with the MoviesService 251 viii | Table of Contents Download at Boykma.Com www.it-ebooks.info [...]... 1, we start out by taking a tour of an ideal enterprise systems layout, highlighting all of the elements that aren’t Rails, as well as noting the various places where Rails can fit in The rest of this book can be divided principally into three major sections The first deals with the Rails framework itself The next few chapters examine Rails itself While Rails gives you a Model-View-Controller (MVC)... Ruby and Rails to tie together all the other xvi | Preface Download at Boykma.Com parts of your application stack: the database, your servers and clients, other services, and users of your application In this book, we begin by putting Rails in the correct context The purpose of the original Rails book, Agile Web Development with Rails by Dave Thomas et al (Pragmatic Bookshelf), was to sell Rails to... leaders in the Rails community itself have advocated not worrying about scaling until you really, really, really need to They say it’s an unnecessary waste of time up front and that Rails scales easily because it’s a share-nothing architecture This, of course, is baloney In the early days, this was good propaganda to get Rails onto developers’ desktops, but today it is simply hurting Rails s image as... If you are new to Rails, the first book to read is Agile Web Development with Rails by Dave Thomas et al (Pragmatic Bookshelf) The book you have in your hands, by contrast, is not a how-to guide for writing your first Rails application This should be the second book you read This book deals in larger concepts, the formulas for how pieces fit together It is not a compendium of the Rails API or a reference... to prove themselves worthy against This doesn’t mean that a Rails application cannot stand up to the challenges imposed by constant traffic and large scale Of course Rails can However, there has been a dearth of public examples, and by the same token, there has not been much public discourse within the Rails community about how to design Rails applications to scale to the same levels that have been... JavaScript, and of course, the language du jour for the application itself But with Ruby on Rails, the bar seems to have dropped almost through the floor You can learn only Rails, and the development of the database, HTML, and JavaScript layers are waved away by the Rails magic It’s an excellent sales pitch for Rails, but is it true? As much as we might like it to be, the sad truth is that if your goal... “architecture” for enterprise web applications, from the ground up What are the topics of web architecture, and why aren’t they found in most books on Rails? In truth, the success or failure of a web application has only partially to do with what is classically called the application layer This may come as a surprise to those who have cut their development teeth on Rails, because the Rails view is that... so definitively that the rest of the stack becomes obsolete? Rails is redefining the landscape of web development Ruby is a wonderful programming language, and the Rails framework does dramatically increase productivity However, databases, legacy systems, and third parties who don’t share our love of Rails are a fact of life Even though Rails does, at times, seem downright magical, it does not make... hardware to achieve those goals? Before diving into the pieces of an enterprise system, or discussing how to build one, a good starting point is to simply define enterprise Unfortunately, that is not an easy task There is no particular set of tools that, if used, will make your architecture qualify as enterprise, even if the word enterprise is in the product names of the tools you use The big companies... their software stack, but they are definitely still enterprise. ” Similarly, there is no single configuration of pieces that together spell enterprise If you looked at the configuration of Google’s servers and compared their it to Amazon’s, the two would look quite different But they are both enterprises nonetheless—it just happens that the two enterprises have different goals, and therefore need different . Boykma.Com www.it-ebooks.info Enterprise Rails Download at Boykma.Com www.it-ebooks.info Other resources from O’Reilly Related titles Advanced Rails Ajax and Rails Learning Rails Learning. Boykma.Com www.it-ebooks.info Enterprise Rails Dan Chak Beijing • Cambridge • Farnham • Köln • Sebastopol • Taipei • Tokyo Download at Boykma.Com www.it-ebooks.info Enterprise Rails by