Web Application Architecture: Principles, Protocols and Practices, 2nd Edition

About the Authors xv

Preface xvi

Acknowledgments xvii

1 Introduction 1

1.1 History and Pre-History of the Web 1

1.2 From Web Pages to Web Sites 3

1.3 From Web Sites to Web Applications 4

1.4 Web 2.0: On-line Communities and Collaboration 4

1.5 The Brave New World of AJAX 5

1.6 Focus of This Book 5

1.7 What Is Covered in This Book 7

1.8 Bibliography 9

2 Core Internet Protocols 11

2.1 Historical Perspective 12

2.2 TCP/IP Architecture 13

2.2.1 Protocol layers 13

2.2.2 Comparison with OSI model 14

2.2.3 The client–server paradigm 14

2.3 TCP/IP Application Services 16

2.3.1 Telnet 16

2.3.2 E-mail 17

2.3.3 Message forums 23

2.3.4 Chat and messaging protocols 24

2.3.5 Security and encryption 24

2.3.6 File server protocols 26

2.4 And Then Came the Web . . . 27

Questions and Exercises 28

2.5 Bibliography 28

3 Birth of the Web: HTTP 29

3.1 Historical Perspective 29

3.1.1 CERN: birthplace of the web 29

3.1.2 Building blocks of the web 30

3.2 Uniform Resource Locator 30

3.3 Fundamentals of HTTP 32

3.3.1 Request–response paradigm 33

3.3.2 Stateless protocol 33

3.3.3 Structure of HTTP messages 34

3.3.4 Request methods 36

3.3.5 Status codes 41

3.4 Better Information Through Headers 44

3.4.1 Support for content types 46

3.4.2 Caching control 49

3.4.3 Security 51

3.4.4 Session support 53

3.5 Evolution of the HTTP Protocol 56

3.5.1 Virtual hosting 57

3.5.2 Caching support 58

3.5.3 Persistent connections 59

3.6 Summary 60

Questions and Exercises 60

3.7 Bibliography 61

4 HTML and Its Roots 63

4.1 Standard Generalized Markup Language 64

4.1.1 SGML declaration 66

4.1.2 Document Type Definition 68

4.2 HTML 72

4.2.1 Evolution of HTML 72

4.2.2 Structure and syntax 73

4.3 HTML Rendering 79

4.3.1 Cascading Style Sheets 79

4.3.2 Associating styles with HTML documents 80

4.4 Summary 82

Questions and Exercises 82

4.5 Bibliography 83

5 XML Languages and Applications 85

5.1 Core XML 86

5.1.1 XML documents 87

5.1.2 XML DTD 88

5.1.3 XML Schema 91

5.2 XHTML 95

5.2.1 HTML 5 97

5.2.2 XHTML MP 97

5.3 Web Services 100

5.3.1 SOAP 100

5.3.2 Representational State Transfer (REST) 105

5.4 XSL 108

5.4.1 XSLT 109

5.4.2 XSL Formatting Objects 111

5.4.3 What is so important about XSL? 116

5.5 Summary 118

Questions and Exercises 119

5.6 Bibliography 120

5.7 Web Links 120

5.8 Endnotes 120

6 Web Servers 121

6.1 Basic Operation 122

6.1.1 HTTP request processing 123

6.1.2 Delivery of static content 125

6.1.3 Delivery of dynamic content 127

6.2 Mechanisms for Dynamic Content Delivery 135

6.2.1 Beyond CGI and SSI 135

6.2.2 Native APIs (ISAPI and Apache Server API) 135

6.2.3 FastCGI 135

6.2.4 Template processing 136

6.2.5 Servlets 137

6.2.6 Java Server Pages 138

6.2.7 Future directions 139

6.3 Advanced Functionality 140

6.3.1 Virtual hosting 140

6.3.2 Chunked transfers 141

6.3.3 Caching support 142

6.3.4 Extensibility 143

6.4 Server Configuration 143

6.4.1 Directory structure 143

6.4.2 Execution 144

6.4.3 Address resolution 145

6.4.4 MIME support 146

6.4.5 Server extensions 146

6.5 Server Security 147

6.5.1 Securing the installation 147

6.5.2 Dangerous practices 148

6.5.3 Secure HTTP 149

6.5.4 Firewall configurations 149

6.5.5 HTTP proxies 150

6.6 Summary 150

Questions and Exercises 151

6.7 Bibliography 152

7 Web Browsers 153

7.1 Overview of Browser Functionality 154

7.2 Architectural Considerations 155

7.3 Overview of Processing Flow in a Browser 157

7.3.1 Transmitting a request 157

7.3.2 Receiving a response 159

7.4 Processing HTTP Requests 162

7.4.1 Constructing the request line 163

7.4.2 Constructing the headers 165

7.4.3 Constructing the request body 166

7.4.4 Transmitting the request 167

7.5 Processing HTTP Responses 167

7.5.1 Processing successful responses 168

7.5.2 Processing responses with other status codes 170

7.6 Cookie Coordination 172

7.7 Privacy and P3P 173

7.8 Complex HTTP Interactions 174

7.8.1 Caching 174

7.8.2 Authorization: challenge and response 178

7.8.3 Using common mechanisms for data persistence 179

7.8.4 Requesting supporting data items 180

7.8.5 Multimedia support: helpers and plug-ins 182

7.9 Summary 184

Questions and Exercises 186

7.10 Bibliography 187

7.11 Web Links 188

7.12 Endnotes 188

8 Active Browser Pages: From JavaScript to AJAX 189

8.1 Pre-History 191

8.2 JavaScript 191

8.2.1 Manipulating page content 194

8.2.2 Client-side form validation 196

8.2.3 Hovering behaviors: image rollover 199

8.2.4 JavaScript Object Notation 201

8.2.5 Summary 202

8.3 Cascading Style Sheets 203

8.3.1 Format of CSS rules 204

8.3.2 Hovering behaviors: the a:hover pseudo-class 208

8.3.3 Summary 209

8.4 DHTML 209

8.4.1 Inner workings 210

8.4.2 Controlling content visibility 210

8.4.3 Leveraging toolkits 212

8.4.4 Client-side validation using toolkits 216

8.4.5 Hovering behaviors using toolkits 217

8.4.6 Widgets 219

8.4.7 Summary 221

8.5 AJAX 221

8.5.1 Content injection: manual approach 222

8.5.2 Content injection: using toolkits 224

8.5.3 Auto-completion 225

8.5.4 Remote validation 228

8.5.5 Where does DHTML end and AJAX begin? 229

8.5.6 Summary 231

8.6 Case Study: 5-Star Rating 231

8.6.1 Designing a star-rating component 232

8.6.2 When you click upon a star: what happens on the server? 236

8.7 Summary 236

Questions and Exercises 237

8.8 Bibliography 237

8.9 Web Links 238

8.10 Endnotes 238

9 Approaches to Web Application Development 239

9.1 Taxonomy of Web Application Approaches and Frameworks 240

9.1.1 Programmatic approaches 240

9.1.2 Template approaches 241

9.1.3 Hybrid approaches 241

9.1.4 Frameworks 242

9.2 Comparative Survey of Web Application Approaches and Frameworks 245

9.2.1 CGI and FastCGI 245

9.2.2 Server-Side Includes (SSI) 246

9.2.3 PHP 246

9.2.4 Java Servlet API 247

9.2.5 Cold Fusion 249

9.2.6 Velocity 251

9.2.7 Active Server Pages and .NET 252

9.2.8 Java Server Pages 254

9.2.9 JSP Model 2 257

9.2.10 Java Standard Tag Library 258

9.2.11 Struts 260

9.2.12 Java Server Faces 261

9.2.13 JBoss Seam 264

9.2.14 Rapid application development: Ruby on Rails 264

9.3 Summary 267

Questions and Exercises 272

9.4 Bibliography 272

10 Web Application Primer 1: Struts and JSTL 275

10.1 Case Study: Virtual Realty Listing Services 276

10.2 Application Requirements 278

10.3 Technology Choices 279

10.4 Overview of Struts 280

10.5 Structure of the VRLS Application 283

10.5.1 Configuration 284

10.5.2 Controller components 287

10.5.3 View components 291

10.5.4 Model components 297

10.6 Design Decisions 299

10.6.1 Abstracting functionality into service classes 299

10.6.2 Including embedded pages to support co-branding 301

10.6.3 Creating and modifying customer profiles in one task 302

10.7 Suggested Enhancements 303

10.7.1 Adding an administrative interface 303

10.7.2 Enhancing the signup process through e-mail authentication 304

10.7.3 Improving partner recognition through a persistent cookie 305

10.7.4 Adding caching functionality to the DomainService Class 306

10.7.5 Paging through cached search results 307

10.7.6 Using XML and XSLT for view presentation 308

10.7.7 Tracking user behavior 310

10.7.8 Using an object-relational mapping tool 310

10.7.9 Adding DHTML and AJAX for an enhanced user experience 311

10.8 Summary 312

Questions and Exercises 312

10.9 Bibliography 313

11 Web Application Primer 2: Ruby on Rails 315

11.1 Comparing Rails with Java EE 316

11.1.1 Similarities 316

11.1.2 Differences 317

11.2 Application Requirements 317

11.3 Building the Administrative Interface as a Rails Application 318

11.3.1 Downloading and installing Ruby and Rails 318

11.3.2 Building an application skeleton 318

11.3.3 Creating a new project and configuring the database 321

11.3.4 Scaffolding for the model, view, and controller classes 322

11.3.5 Enhancing the application 326

11.4 Benefits and Drawbacks of Using Rails 339

11.4.1 How rapid is rapid application development? 339

11.4.2 Database support 340

11.4.3 Limitations of scaffolding 340

11.4.4 Scalability 341

11.4.5 Performance and clustering 341

11.4.6 Version 2.0 issues 341

11.4.7 Is Rails web-designer-friendly? 342

11.5 Whither Enterprise Java? 343

11.6 Summary 344

Questions and Exercises 344

11.7 Bibliography 345

11.8 Web Links 345

11.9 Endnotes 345

12 Search Technologies 347

12.1 Overview of Algorithms 348

12.1.1 Historical perspective 348

12.1.2 Basic vector-space algorithm 349

12.1.3 Common enhancements 355

12.1.4 Word clustering 355

12.1.5 Custom biases 357

12.2 Searching the Web 358

12.2.1 Google page ranking 358

12.2.2 Web spiders 359

12.2.3 Summary 361

12.3 Site Search Applications 361

12.3.1 General architecture 362

12.3.2 Lucene 363

12.3.3 OneBox applications 367

12.4 Search Engine Optimization 369

12.4.1 Robots.txt 370

12.4.2 Sitemaps 372

12.4.3 Sitemap extensions 376

12.4.4 Site and URL structure 376

12.4.5 Black Hat SEO 377

12.5 Summary 378

Questions and Exercises 379

12.6 Bibliography 380

12.7 Web Links 380

12.8 Endnotes 380

13 Trends and Directions 381

13.1 XML Query Language 382

13.2 Semantic Web 385

13.2.1 Resource Description Framework (RDF) 386

13.2.2 Composite Capabilities/Preference Profiles 392

13.2.3 RDF query language 393

13.3 Future of Web Application Frameworks 396

13.3.1 One more time: separate content from presentation 396

13.3.2 Use the right tools for the job 398

13.3.3 Simplicity 399

13.4 Current Trends 404

13.4.1 Everything old is new again 404

13.4.2 Social networking and community web sites 405

13.4.3 Cloud computing and “Weblications” 405

13.5 Summary 407

Questions and Exercises 407

13.6 Bibliography 408

13.7 Web Links 408

13.8 Endnotes 408

14 Conclusions 409

Index 413