Architecture for Blockchain Applications

Foreword......Page 3
Contents......Page 11
--- Blockchain in Software Architecture......Page 15
1.1 What Is Blockchain and Why Should I Care?......Page 16
1.1.1 Defining Blockchain......Page 18
1.1.2 Smart Contracts and Decentralized Applications......Page 20
1.1.3 Cryptocurrencies and Tokens......Page 21
1.2 Blockchain-Based Applications......Page 22
1.2.1 Enterprise and Industry......Page 23
1.2.2 Financial Services......Page 24
1.2.3 Government Services......Page 26
1.3 Blockchain Functionality......Page 27
Transactions......Page 28
Digital Assets......Page 30
1.3.2 Blockchain as a Computational Infrastructure......Page 31
1.4.2 Non-functional Properties of Blockchain......Page 32
1.5.2 Designing Blockchain-Based Applications......Page 34
1.7 Further Reading......Page 37
2.1 Bitcoin......Page 39
2.1.1 Bitcoin Transactions......Page 40
2.1.2 Script......Page 41
2.1.3 Mining......Page 42
2.1.4 Accounts and State......Page 43
2.1.5 Nakamoto Consensus......Page 45
2.1.7 Wallets......Page 46
2.2.1 Ethereum Protocol......Page 47
2.2.2 Ethereum Transactions......Page 48
2.2.3 Smart Contract......Page 49
2.2.5 Decentralized Application (dapp)......Page 51
2.3 Hyperledger Fabric......Page 52
2.3.3 Nodes......Page 53
2.3.4 Transactions......Page 54
2.3.5 Consensus......Page 55
2.5 Further Reading......Page 56
3.1 Fundamental Properties of Blockchain......Page 57
3.2 Decentralization......Page 58
3.2.1 Permission......Page 60
3.2.2 Deployment......Page 61
3.3 Ledger Structure......Page 62
3.4 Consensus Protocol......Page 63
3.5 Block Configuration......Page 65
3.6 Auxiliary Blockchains......Page 66
3.7 Anonymity......Page 69
3.10 Further Reading......Page 70
4.1 Agricultural Supply Chains......Page 72
4.1.1 Key Non-functional Requirements......Page 73
4.1.2 Conventional Technology......Page 74
4.1.4 Non-functional Property Discussion......Page 75
4.2 Open Data Registry......Page 78
4.2.1 Key Non-functional Requirements......Page 79
4.2.3 A Blockchain Solution......Page 80
4.2.4 Non-functional Property Discussion......Page 81
4.3 International Money Transfers......Page 82
4.3.2 Conventional Technologies......Page 83
4.3.4 Non-functional Property Discussion......Page 85
4.4 Electricity Contract Selection and Continuous Reporting......Page 86
4.4.3 A Blockchain Solution......Page 87
4.5 Further Reading......Page 89
--- Architecting Blockchain Applications......Page 91
5.1 Blockchain as an Architectural Element......Page 92
5.2 Blockchain as Storage Element......Page 93
5.2.1 Comparison with Centralized Databases......Page 94
5.2.3 Comparison with Peer-to-Peer Data Storage......Page 95
5.2.4 Comparison with Replicated State Machines......Page 96
5.3 Blockchain as Computational Element......Page 97
5.4.1 Data Communication......Page 98
5.5 Blockchain as an Asset Management and Control Mechanism......Page 99
5.6 Integrating Blockchain into a System as a Component......Page 100
5.8 Further Reading......Page 101
6.1 Evaluation of Suitability......Page 102
6.1.1 Multiparty......Page 103
6.1.2 Trusted Authority......Page 104
6.1.4 Data Immutability and Non-repudiation......Page 105
6.1.5 High Performance......Page 106
6.1.6 Transparency......Page 107
6.2.1 Use Case 1: Supply Chain......Page 109
6.2.2 Use Case 2: Electronic Health Records (EHRs)......Page 111
6.2.3 Use Case 3: Identity Management......Page 112
6.3 Design Process for Blockchain-Based Systems......Page 113
6.3.1 Trade-Off Analysis......Page 114
6.3.3 On-Chain vs. Off-Chain......Page 115
Data......Page 116
Other Considerations......Page 118
6.3.5 Deployment and Operation......Page 119
6.5 Further Reading......Page 120
7 Blockchain Patterns......Page 121
7.1.1 Pattern 1: Oracle......Page 123
7.1.2 Pattern 2: Reverse Oracle......Page 125
7.1.3 Pattern 3: Legal and Smart Contract Pair......Page 127
7.2.1 Pattern 4: Encrypting On-Chain Data......Page 129
7.2.2 Pattern 5: Tokenization......Page 132
7.2.3 Pattern 6: Off-Chain Data Storage......Page 134
7.2.4 Pattern 7: State Channel......Page 136
7.3.1 Pattern 8: Multiple Authorization......Page 139
7.3.2 Pattern 9: Off-Chain Secret Enabled Dynamic Authorization......Page 141
7.3.3 Pattern 10: X-Confirmation......Page 143
7.4.1 Pattern 11: Contract Registry......Page 145
7.4.2 Pattern 12: Data Contract......Page 148
7.4.3 Pattern 13: Embedded Permission......Page 150
7.4.4 Pattern 14: Factory Contract......Page 152
7.4.5 Pattern 15: Incentive Execution......Page 154
7.5 Summary......Page 155
7.6 Further Reading......Page 156
8.1 Introduction......Page 157
8.2.1 Motivation......Page 158
8.2.2 Challenges of Collaborative Business Process Execution......Page 159
8.2.3 Blockchain-Based Collaborative Process Execution......Page 160
Design Time: Translator......Page 162
Runtime Environment: Executing Processes as Smart Contracts......Page 163
8.2.4 Discussion......Page 168
8.3 Model-Driven Registry Generation for Blockchain......Page 170
8.3.1 Registries on Blockchain......Page 171
8.3.2 A Tool for Registry Generation: Regerator......Page 172
Smart Contract Generator......Page 173
Registry of Registries on Blockchain......Page 174
8.3.3 Exemplar Case Study: Open Data Registry......Page 175
Implementation......Page 176
Discussion......Page 177
8.4 Summary......Page 178
8.5 Further Reading......Page 179
--- Quality Impact of Blockchain......Page 181
9 Cost......Page 182
9.1 On-Chain Data Cost......Page 183
9.3 Cost Models......Page 185
9.3.1 Ethereum Blockchain Cost Model......Page 186
9.3.2 Amazon SWF Cost Model......Page 188
9.4.1 Experiment Setup, Methodology, and Benchmarking......Page 191
VM Throughput Measurements......Page 192
9.4.2 Blockchain Results......Page 193
9.4.3 Amazon SWF Results......Page 194
9.4.4 Completeness, Correctness, and Comparative Analysis......Page 195
9.4.5 On the Volatility of Cryptocurrency to Fiat Currency Exchange Rate......Page 197
9.5.1 Cost of Distrust......Page 199
9.5.3 Scaling Triggers for Blockchain and SWF......Page 200
9.6 Summary......Page 201
9.7 Further Reading......Page 202
10.1 Performance Characteristics of Blockchain......Page 203
10.3 Predicting Latency for Blockchain-Based Systems......Page 205
10.3.1 Benchmarking Transaction Inclusion and Commit Times......Page 206
10.3.2 Blockchain-Based System Performance Modelling......Page 208
Component Repository Model......Page 209
Usage Model......Page 210
10.3.3 Using Simulation for System-Level Latency Predictions......Page 212
Applying Simulation to Other Systems......Page 213
10.4.1 Choice of Inter-Block Time......Page 214
10.4.2 Choice of Number of Confirmation Blocks......Page 215
10.5 Summary......Page 216
10.6 Further Reading......Page 217
11 Dependability & Security......Page 219
11.1 Confidentiality......Page 220
11.2 Integrity......Page 221
11.3 Safety......Page 222
11.4 Maintainability......Page 223
11.5 Availability and Reliability......Page 224
11.6 Variation in Blockchain Transaction Inclusion......Page 225
11.6.1 Variation in Bitcoin Transaction Commit Time......Page 226
11.6.2 Variation in Ethereum Transaction Commit Time......Page 229
11.7 Aborting and Retrying Blockchain Transactions......Page 235
11.7.2 Aborting and Retrying Transactions in Bitcoin......Page 236
11.7.3 Experiments for Aborting Transactions in Ethereum......Page 237
11.9 Further Reading......Page 240
--- Case Studies......Page 242
12.1.1 Global Agricultural Supply Chains......Page 243
12.1.2 Blockchain and Agriculture......Page 244
12.2.1 Building Digital Trust......Page 245
12.2.2 AgriDigital's Blockchain Solution......Page 246
12.2.4 Pilots and Proof-of-Concept Overview......Page 248
12.3.1 Overview......Page 251
12.3.2 Pilot Scenarios......Page 252
12.3.3 Design Decisions......Page 254
12.4 Summary......Page 258
13.1 Introduction and Background......Page 260
13.2 The MVP Prototype......Page 262
13.3 Building Tokenvote......Page 264
Planned Architecture......Page 265
Final Architecture......Page 267
Qualities and Trade-offs......Page 269
13.4.1 Indexing and Externally Accessing Data......Page 270
13.4.2 Splitting Up Contracts......Page 272
Adding a Backend Smart Contract......Page 273
Using Libraries......Page 274
Replacing Smart Contracts......Page 275
SecureVote's First Upgrade......Page 276
Atomic Upgrades and Tokenvote......Page 278
13.4.4 Reducing Complexity and Cost......Page 280
13.6 Further Reading......Page 281
14.1 Introduction and Background......Page 282
14.1.1 Traceability Process......Page 283
14.2.2 On-Chain vs. Off-Chain......Page 285
14.2.3 Design of Smart Contracts......Page 287
14.2.5 Permission Control and Blockchain Management......Page 289
14.3.1 Qualitative Analysis: Adaptability......Page 290
14.3.2 Quantitative Analysis: Latency of Writing and Reading......Page 293
14.4.1 Architectural Design of Blockchain-Based Systems......Page 294
14.5 Summary......Page 295
Epilogue......Page 297
Refs......Page 300
Index......Page 306