Dcp cas box 14 turbotax

Series Editor, David Clark

Understanding Networked Applications: A First Course David G. Messerschmitt

Integrated Management of Networked Systems: Concepts, Architectures, and Their Operational Application

Heinz-Gerd Hegering, Sebastian Abeck, and Bernhard Neumair

Virtual Private Networks

Dennis Fowler

Networked Applications: A Guide to the New Computing Infrastructure David G. Messerschmitt

Modern Cable Television Technology: Video, Voice, and Data Communications Walter Ciciora, James Farmer, and David Large

Switching in IP Networks: IP Switching, Tag Switching, and Related Technologies Bruce S. Davie, Paul Doolan, and Yakov Rekhter

Wide Area Network Design: Concepts and Tools for Optimization Robert S. Cahn

Optical Networks: A Practical Perspective Rajiv Ramaswami and Kumar Sivarajan

Practical Computer Network Analysis and Design James D. McCabe

Frame Relay Applications: Business and Technology Case Studies James P. Cavanagh

High-Performance Communication Networks Jean Walrand and Pravin Varaiya

Computer Networks: A Systems Approach Larry L. Peterson and Bruce S. Davie

David G. Messerschmitt

University of California, Berkeley

Preface xxv

Chapter 1 Introduction 1

Part I: The Applications

Chapter 2 Applications Supporting Individuals and Groups 17

Chapter 3 Applications Supporting Organizations 59

Part II: Architecture

Chapter 4 Information Technology 107

Chapter 5 Client-Server Computing 139

Chapter 6 Modularity and Layering 157

Part III: Industry and Government Context

Chapter 7 The Computer and Communications Industries 197

Chapter 8 Economics and Policy 231

Part IV: Making It Happen

Chapter 9 Applications and the Organization 273

Chapter 10 Application Architecture 293

Chapter 11 Programming an Application 325

Part V: Infrastructure

Chapter 12 Communication Services 345

Chapter 13 Trustworthiness 369

Chapter 14 Electronic Payments 403

Chapter 15 Data Sharing 415

Chapter 16 Communications Middleware 441

Part VI: Performance

Chapter 17 Scalability 463

Chapter 18 Collective Issues in Networking 493

Chapter 19 Network Architecture and Protocols 517

Chapter 20 Communications Providers and Links 539

Glossary 565

References 591

Index 599

About the Author 625

Preface xxv

Chapter 1 Introduction 1

1.1The Evolution of Computing 2 1.1.1 Previous Phases of Computing 2 Technology View 2 User and Organization View 3 Legacy Applications 4 1.1.2 The Future 5 Electrification: Lessons from an Earlier Technological Advance 5 1.2Overviewof the Book 7 1.2.1 Applications 7 1.2.2 Architecture 8 1.2.3 Industry and Government Context 9 1.2.4 Making It Happen 10 1.2.5 Infrastructure 11 1.2.6 Performance 12

Part I: The Applications

Chapter 2 Applications Supporting Individuals and Groups 17

2.1 Three Ingredients 17 2.1.1 Information Technology 18 What's an Application? 18 2.1.2 Information Content 19 2.1.3 Users and Applications 19 2.2 Social Applications 21 2.2.1 Characteristics of User Groups 22 2.2.2 Styles of Social Applications 24 Communication Style 25 Coordination Style 27 2.2.3 Remote Conferencing with Shared Workspace 28 Collaborative Authoring 28 2.2.4 Groupware 29 2.2.5 Discussion Forums 32

Calendar and Scheduling 32 Chatroom 33 Newsgroup 33 Listserver 34 2.2.6 Cyberspace Applications 34 Broadcasting 35 Mass Publication 35 Information Retrieval 36 Consumer Electronic Commerce 36 World Wide Web 36 Recommendation Sharing 37 2.2.7 Back to the Big Picture 37 2.3 Information Management 38 2.3.1 What Is Information? 39 2.3.2 Finding Useful Information 41 User-Directed Access 41 Paying for Information 42 Assistance from Others 43 Third-Party or Collective Recommendations 43 Third-Party Organization and Indexing: Digital Libraries 45 Searching and Indexing 45 2.3.3 Autonomous Information Sources 46 e-Print: Scholarly Publication in Cyberspace 46 User Control: Subscriptions 47 User Awareness: Notifications 48 Timing 49 Push and Pull in Social Applications 49 Role of Push and Pull in Work Groups 50 2.4 Education and Training 51 2.5 *Open Issue: Information and Communication Glut 52

Chapter 3 Applications Supporting Organizations 59

Problems and Obstacles 61 3.1 Examples of Organizational Applications 62 3.1.1 Customer Care 63 3.1.2 On-Line Bookselling 66 3.1.3 On-Line Stock Trading 68 3.1.4 Floral Delivery Service 69 3.1.5 Observations 71 3.2 Departmental Applications 72 3.2.1 On-Line Transaction Processing 72 3.2.2 Workflow 73

3.2.3 From Centralized to Decentralized Computing 74 3.3 Enterprise Applications 76 3.3.1 Operations 76 Business Processes 76 Business Transformation 77 Enterprise Resource Planning 79 SAP: Largest ERP Vendor 80 3.3.2 Decision Support 81 3.3.3 Knowledge Management 81 Legacy Applications 81 The Year 2000 Problem 82 3.4 Electronic Commerce 83 3.4.1 Types of E-Commerce Applications 83 Data Warehouses and Data Mining 83 3.4.2 Steps in a Sale 84 Matching Buyers and Sellers 84 Negotiating Terms and Conditions 86 Consummation 87 Auctions 87 Customer Support 88 3.4.3 Role of Intermediaries 88 3.4.4 Consumer E-Commerce 89 Amazon.com: On-Line Merchant 89 3.4.5 Interconsumer E-Commerce 91 3.4.6 Inter-Enterprise E-Commerce 91 Direct Procurement 92 Dell Computer and Mass Customization 94 Indirect Procurement 95 3.5 Critical Societal Infrastructure 96 3.6 Parallels between Social and Computing Systems 97 3.7 *Open Issues 98 3.7.1 The Productivity Paradox 99 3.7.2 How Are New Organizational Applications Invented and Developed? 99 3.7.3 Better Accommodating Change 100

Part II: Architecture

Chapter 4 Information Technology 107

4.1 Information Content 108 4.1.1 Bits as a Building Block 108 4.1.2 Information Is Represented by Data 108 Bits Are Easy to Manipulate, Store, and Communicate 108 Any Information Can Be Represented by Bits 109

4.1.3 Data Processing 111 4.2 Building Blocks 113 4.3 System Architecture 114 4.3.1 Elements of Any Architecture 115 Architecture Is Common 115 4.3.2 Emergence 116 4.3.3 Hierarchy 116 Hierarchy Is Common 117 4.4 Networked Computing Infrastructure 118 4.4.1 Infrastructure Software Layering 120 4.4.2 Communications 121 Functions of an Operating System 121 Network Functions 122 Network Topology 123 Packets 123 4.4.3 Storage 125 File System 125 Database 125 Functions of a File System 125 Database Management System (DBMS) 126 4.5 The Internet 127 Relational Databases 127 4.5.1 Intranet 128 4.5.2 Extranet 129 4.5.3 Nomadic and Mobile Internet Access 131 4.5.4 Internet Application Suite 132 4.6 *Open Issues 132 4.6.1 Pacing Change 132 4.6.2 The Future of Intranets 133 4.6.3 Archiving Digital Information 133

Chapter 5 Client-Server Computing 139

5.1 Two Host Architectures 140 5.1.1 Client-Server Architecture 140 History of Client-Server Computing 140 5.1.2 Peer-to-Peer Architecture 142 5.2 Three-Tier Client-Server Architecture 144 5.2.1 Thin and Ultrathin Clients 146 5.2.2 World Wide Web 147 An Ultrathin Client: The Network Computer (NC) 147 5.3 Application Examples 148 5.3.1 On-Line Book Merchant 148

5.3.2 Floral Delivery Service 151 5.4 *Trends in Client-Server Computing 152 5.5 *Open Issue: Beyond Client-Server Computing 153

Chapter 6 Modularity and Layering 157

6.1 Software Complexity 158 6.2 Modularity 159 6.2.1 Properties of Modularity 160 Modularity in Organizations 160 6.2.2 Granularity and Hierarchy 162 6.2.3 Interfaces 163 Interfaces as Contracts 163 Actions 164 Hardware Interfaces 164 Parameters and Returns 165 Action Menus 165 Interfaces and Organizations 166 Data Types 167 Data Types 168 Protocols 169 Human Interfaces 170 Messages 170 Anatomy of an Action Invocation 170 6.3 More on Layered Infrastructure Software 171 6.3.1 Goals of the Infrastructure 171 6.3.2 Layering Principle 172 Layering in Applications 172 Industrial Layering Example 173 6.3.3 The Layers in a Computing Infrastructure 174 6.3.4 Data and Information in Layers 176 A Package of Data 177 Responding to Platform Heterogeneity 178 Two Ways to Convert Representations 180 A Middleware Example 180 More Layering Principles 182 Data Integrity 183 6.3.5 The Horizontal Layer Interface 184 6.3.6 The Spanning Layer 185 6.4 *More on Good Architectures 186 6.4.1 Abstraction 187 6.4.2 Encapsulation 187 Example of Abstraction: The Flora 187

Abstraction in Organizations 187 6.4.3 Flexibility 189 Modularity and the Economy 189

Part III: Industry and Government Context

Chapter 7 The Computer and Communications Industries 197

7.1 Participants, Products, and Services 197 7.1.1 Components and Integration 198 7.1.2 Suppliers, Providers, and Consumers 199 7.1.3 Types of Information Goods 200 7.1.4 Types of Software Goods 202 7.1.5 Equipment 203 7.2 The Changing Industry Structure 204 7.2.1 The Role of Architecture 204 7.2.2 From Stovepipe to Integrated Infrastructure 205 7.2.3 Less Vertical Integration and More Diversification 209 Dell as a Subsystem Integrator 209 Information Appliances 209 7.2.4 Venture Capital and Start-Ups 212 7.2.5 Computing/Communications Convergence 213 7.3 Standardization 215 Hardware Standards 215 7.3.1 Reference Models and Interfaces 216 7.3.2 Industry Organization and Standardization 216 EDI Standards 216 Document Standards 216 7.3.3 The Standardization Process 217 International Organization for Standards (ISO) 218 Internet Engineering Task Force (IETF) 219 7.3.4 Who Controls and Who Enforces Standards? 219 7.3.5 Why Open Standards? 221 Object Management Group (OMG) 221 7.3.6 Standardization Has Downsides Too 222 7.4 *Open Issues 224 7.4.1 Industry Organization 224 7.4.2 The Best Standardization Processes 225

Chapter 8 Economics and Policy 231

8.1 Obstacles to Change 231 8.1.1 Network Effects 232 Metcalfe's Law 232 *Economic Model of Network Effects 233

Standardization and Network Effects 235 Network Effects in Enterprise and Commerce Applications 236 Success of the Web 237 8.1.2 Lock-in 238 Value of Locked-in Consumer 238 Supplier and Industry Lock-in 239 Open Systems and Lock-in 240 8.1.3 *Path-Dependent Effects 240 Microsoft vs. Everybody Else 241 8.2 Challenges for Suppliers 242 8.2.1 *Technical Properties of Information 242 Digital Information as One Basis of Life 243 8.2.2 Economic Properties of Information 244 Regeneration of Data 244 8.2.3 Software as a Special Case 246 Forms of Recommendation 246 8.2.4 Equipment 247 8.2.5 *Protecting Investments with Intellectual Property 247 8.2.6 Selling Content and Software 247 Semiconductor Manufacturers: Moore's Law 247 Standardization and Competition 248 Value of Content 249 Value of Software 250 *Price Discrimination and Versioning 251 Quality and Features of Shrink-Wrapped Applications 251 Auctions and Price Discrimination 252 8.3 Government Roles 254 8.3.1 Protecting Intellectual Property 254 Copyrights 255 Copyrighting Software 256 Intellectual Property as a Strategic Tool 256 Patents 257 Software Patents 258 Patents and Standardization 258 8.3.2 Government Policies and Laws 259 Privacy 259 Difficulties with Software Patents 259 Content Regulation 260 Law Enforcement and National Security 261 Antitrust Law 261 Telecommunications Regulation 262 8.4 *Open Issues 264

8.4.1 Sovereignty and the Global Internet 264 8.4.2 The Language of the Internet 265 8.4.3 A New Partnership 265

Part IV: Making It Happen

Chapter 9 Applications and the Organization 273

9.1 Organizational Rationale for Networked Computing 274 9.1.1 Scalability 274 9.1.2 Administration 275 9.2 Acquisition Options 276 9.2.1 Make vs. Buy 277 9.2.2 Purchase Terms and Conditions 278 9.3 Application Lifecycle 279 9.3.1 Lifecycle Model of Development 279 Conceptualization 280 Analysis 280 Automated Development: CASE Tools 280 Architecture Design 281 Development Evolution 282 Testing and Evaluation 282 Deployment 282 Operations, Maintenance, and Upgrade 283 9.3.2 Alternative Development Methodologies 283 9.4 Examples 285 9.4.1 Customer Care 285 9.4.2 On-Line Bookseller 286 9.4.3 Stock Trading 287 9.4.4 Floral Delivery 287 9.4.5 Observations 288 9.5 Open Issue: Best Development Methodology 289

Chapter 10 Application Architecture 293

10.1 Major Considerations in Architecture Design 294 10.1.1 Decomposition vs. Assembly 294 Decomposition: Objects 296 Assembly: Software Components 296 10.1.2 Software Reuse 297 Component Standards 297 10.1.3 Location of Data and Processing 298 Reuse in Industry 298 10.1.4 Data as an Asset 300 Partitioning in Organizations 300

10.2 Object-Oriented Architectures 302 10.2.1 Objects and the Application Context 303 Physical and Information Entities 303 Software Objects 304 Relationship of Software and Real-World Entities 307 Representation Objects 309 Proxy Objects 309 Modeling Objects 310 10.2.2 Objects as Information Entities 311 10.2.3 Class 312 10.2.4 Visual Architecture Modeling 313 10.2.5 Dealing with Legacy Systems 313 10.3 Components and Frameworks 315 10.3.1 Software Components 315 Components, Frameworks, and the Industrial Revolution 316 Designing Components 317 Scripting and Visual Assembly 317 10.3.2 Software Frameworks 318 Example: Compound Document 319

Chapter 11 Programming an Application 325

11.1 Algorithms, Protocols, and Policies 325 11.1.1 Algorithms and Flowcharts 327 11.1.2 Protocols and Interaction Diagrams 329 11.1.3 Three Common Protocols 330 The Hypertext Transfer Protocol (HTTP) 332 11.2 Locating Things 333 11.2.1 Names 333 11.2.2 Addresses 334 11.2.3 References 334 Name Services 334 11.3 *Programs and Languages 335 Dominant Programming Languages 335 11.3.1 Imperative vs. Declarative Languages 336 11.3.2 Object-Oriented Programming Language 337 Other Programming Issues 337 11.3.3 Scripting vs. Systems Programming Languages 338 11.3.4 Program Execution 338

Part V: Infrastructure

Chapter 12 Communication Services 345

12.1 Generic Communication Services 346

12.1.1 Message Service 347 Abstraction of Communication Services 347 Is a Message Delivered for Sure? 348 12.1.2 Message Queueing and Multiplexing 349 Queueing 349 Multiplexing 350 12.1.3 Message with Reply Service 351 Remote Method Invocation 353 Supporting Push and Pull 353 Timing and Concurrency 354 12.1.4 The Conversation 356 Multimedia Transport 358 Some Advantages of a Conversation 358 12.1.5 The Broadcast 361 12.2 Internet Communication Services 362 12.2.1 Internet Protocol (IP) 362 Origins of the Internet 362 12.2.2 User Datagram Protocol (UDP) 363 12.2.3 Transmission Control Protocol (TCP) 364 12.2.4 Internet Inter-ORB Protocol (IIOP) 364 12.2.5 Streaming Multimedia 365 RMI Can Be Layered on Messages 365 Internet Streaming Multimedia Protocols 365

Chapter 13 Trustworthiness 369

13.1 Availability 370 13.1.1 Intrinsic Reliability 371 Software Bugs 371 Configuration and Operation 372 Emergent Behavior 372 Cost of Reliability 373 Diversity, Reliability, and Security 373 13.1.2 Security: Countering Deliberate Threats 374 Other Uses of Data Replication 374 How Effective Is Redundancy? 375 13.2 Security Measures 376 13.2.1 Postal System Analogy 376 Availability, Security, and the Market 376 13.2.2 Examples of Threats 378 Security Analysis and Planning 378 Computer Viruses 380 13.2.3 Pillars of Security 381

13.3 Confidentiality 381 Simplistic Encryption Algorithms 382 13.3.1 Symmetric vs. Asymmetric Encryption 383 Trusted Systems 384 13.3.2 Encryption Algorithms 385 13.4 Authentication 386 Attacks on Confidentiality Protocols 386 13.4.1 Biometrics 387 13.4.2 Secrets 388 13.4.3 Digital Certificates and Certificate Authorities 389 Challenge-Response Protocol 389 Certificates and a National Identity Card 390 13.5 Signatures 391 Message Digest 391 13.6 Security Systems 393 A Chain of Trust 393 13.6.1 Confidential Sessions 394 Example of a Combination Protocol 394 13.7 Example: Stock Trading Application 395 Session Keys 395 13.8 Open Issues 396 13.8.1 Increasing Vulnerability 396 13.8.2 National Security and Law Enforcement Needs 396 Web Browser Security 396 13.8.3 Theft and Piracy of Software and Information 397 Final Defense: Legal Sanctions 397

Chapter 14 Electronic Payments 403

14.1 Some Benefits to Electronic Payments 403 14.2 Types of Payments 404 14.3 Credit or Debit Card Payments 405 14.3.1 Problems with Card Payments 405 14.3.2 Secure Electronic Transactions (SET) 406 *SET Chain of Trust 407 *SET Order-Authorization Protocol 407 14.4 Digital Cash 408 14.4.1 Challenges for Digital Cash 408 Many Questions about Digital Cash 408 Types of Smartcards 409 14.4.2 Privacy and Digital Cash 410 Privacy and Anonymous Digital Cash 411

Chapter 15 Data Sharing 415

15.1 Database Management 416 15.1.1 The Relational Model 418 Application Logic and Tables 420 Data Warehouses and OLAP 420 *Objects and Tables 421 15.1.2 *Extending the DBMS 423 15.2 Documents and XML 423 Extending Databases to Objects: ORDBMS and ODBMS 423 15.2.1 Markup Languages 424 Applications across Organizational Boundaries 424 eXtensible Markup Language (XML) 425 15.3 Transaction Processing 426 15.3.1 Example: Travel Reservations 427 15.3.2 Role of Transaction Processing 428 15.3.3 What's in a Transaction 429 The ACID Properties of Transactions 429 15.3.4 Transaction Processing Architecture 431 15.3.5 *Transaction Protocols 432 Open Transaction Processing Standards 432 15.3.6 Examples 433 Automatic Teller Networks 433 E-Commerce 433 Stock Trading 434 15.4 Example: Stock Trading System 434 15.4.1 The Databases 434 15.4.2 The Transactions 435 15.4.3 Inter-Enterprise Messages 437 15.5 *Open Issue: Future of the DBMS 437

Chapter 16 Communications Middleware 441

16.1 Messaging and Queueing Middleware 443 16.2 Mobile Code, Objects, and Agents 445 16.2.1 Advantages of Mobile Code 445 Interactivity and Scalability 446 Interoperability 447 Mobile Code and Objects 447 Mobile Code and Network Effects 447 Information Access 448 16.2.2 Mobile Code and Object Middleware 449 16.3 Distributed Object Management 449 Competing Distributed Object Visions: DCOM and CORBA 450

16.3.1 One DOM Standard: CORBA 451 16.3.2 Changing Data Representations 451 The OMG Process 451 16.3.3 Interface Discovery 453 Portability vs. Interoperability 453 16.3.4 Services 454 16.3.5 Interoperability among ORBs: IIOP 454 16.3.6 Horizontal and Vertical Facilities 455 16.4 Open Issues 455 16.4.1 Middleware Service Providers? 455 16.4.2 Middleware Spanning Layer? 456 16.4.3 Middleware vs. XML and the Web 456

Part VI: Performance

Chapter 17 Scalability 463

17.1 Metrics 464 17.1.1 Performance 464 17.1.2 Quality 466 17.1.3 Contributors to Performance and Quality 467 17.2 The Role of Concurrency 468 17.2.1 Concurrency with Multiple Hosts 469 17.2.2 Concurrency in a Single Host 470 Different Forms of Multitasking 471 17.2.3 Resource Conflicts and Transactions 472 Why Networks Use Packets 472 Concurrency Control 474 17.3 *Scalability as a Performance Consideration 475 Scalability in Production 475 17.3.1 Blocking 476 17.3.2 Duplicated Work 476 17.3.3 Faulty Load Balancing 476 17.3.4 Congestion 477 Congestion in Processing 478 Modeling Congestion 478 Congestion on Communication Links 480 Congestion in Storage 481 17.3.5 Role of Application Architecture 481 Designing High-Performance Systems 482 17.3.6 Role of Mobile Code 483 17.3.7 Example: Stock Trading Application 484 17.4 *Operating Systems 485 17.4.1 Processes 485

Today's Operating Systems 485 Operating Systems and Winner-Take-All Effects 485 17.4.2 *Other Operating System Functions 486 What Is the Difference between RPC and RMI? 486 Multithreading 487

Chapter 18 Collective Issues in Networking 493

18.1 Functions of a Network 493 18.1.1 Sharing Communication Links: Statistical Multiplexing 494 18.1.2 Packet Forwarding and Routing 495 Advantage of Statistical Multiplexing 495 18.1.3 Name Services 497 Routing 497 Hierarchical Names and Addresses 498 Simulcast and Multicast 498 18.1.4 Flow Control 499 The Value of a Domain Name 499 18.1.5 Network Congestion 500 Congestion Instability 501 Implementation of Congestion Control 503 Congestion as Network Externalities 503 18.2 Quality of Service (QoS) 505 Cost of Congestion Control 505 18.2.1 The Internet Transport Services and QoS 506 Applications Have a QoS Too 506 18.2.2 Integrated Services 507 ATM: Another Integrated Services Network 507 18.2.3 Pricing of Network Services 508 Evolution of the Internet 508 18.3 Open Issues 510 18.3.1 Future of the Internet 510 Today's Internet Pricing 510 18.3.2 Multiple Networks 511

Chapter 19 Network Architecture and Protocols 517

19.1 Network Architecture 517 19.1.1 Network Protocols 518 The ISO Reference Model 518 19.1.2 Packet Encapsulation 519 19.1.3 Packet Fragmentation and Reassembly 520 19.1.4 Protocol Layering 521 19.2 *Internet Protocols 523

19.2.1 Internet Protocol Architecture 524 Some Lessons from the Internet Architecture 524 TCP and the PTN 526 19.2.2 Packet Header Formats 527 Managing Addresses 528 19.2.3 IP Multicast 529 19.2.4 Domain Name System 529 19.2.5 Reliable and Ordered Delivery 532 19.2.6 Flow Control 535 19.2.7 Integrated Services 535 TCP Congestion Control 535 RSVP: Service Models for Multicast 536

Chapter 20 Communications Providers and Links 539

20.1 Communications Service Providers 539 20.1.1 Trends in Communications 541 20.1.2 Data Communications 541 20.1.3 Communications Regulation 542 20.2 Current Developments in Internet Access 544 20.2.1 Broadband Network Access for Residences 544 Wireless Access Protocol (WAP) 545 20.2.2 Nomadic and Untethered Internet Access 546 Internet Access with Incremental Investments 546 20.2.3 IP Telephony 547 Internet Roaming 547 20.2.4 Integrated IP Networks 549 20.3 *Communication Links 549 Components of Message Latency 551 Fiber Optics and Optical Networking 551 20.3.1 Message Latency on a Link 552 20.3.2 Impact of Message Latency on Application Performance 554 20.3.3 Why Broadband? 554 Processing and Message Latency 554 20.3.4 Mitigating Communications Bottlenecks 555 Data Caching 555 Caching Is Used in Many Circumstances 556 Data Compression 557 Caching and Copyright Law 557 Mobile Code 558 20.4 Open Issues 558 20.4.1 Is Communications Regulation Needed? 558 Data Compression Algorithms 558