Reactive Design Patterns
Does an excellent job explaining Reactive architecture and design, starting with first principles and putting them into a practical context.
Reactive Design Patterns is a clearly written guide for building message-driven distributed systems that are resilient, responsive, and elastic. In this book you'll find patterns for messaging, flow control, resource management, and concurrency, along with practical issues like test-friendly designs. All patterns include concrete examples using Scala and Akka.
Table of Contents detailed table of contents
Part 1: Introduction
1. Why Reactive?
1.1. The anatomy of a Reactive application
1.2. Coping with load
1.3. Coping with failures
1.4. Making it responsive
1.5. Avoiding the ball of mud
1.6. Integrating non-reactive components
1.7. Summary
2. A walk-through of the Reactive manifesto
2.1. Reacting to Users
2.1.1. Understanding the Traditional Approach
2.1.2. Analyzing Latency with a Shared Resource
2.1.3. Limiting Maximum Latency with a Queue
2.2. Exploiting Parallelism
2.2.1. Reducing Latency by Parallelization
2.2.2. Improving with Composable Futures
2.2.3. Paying for the Serial Illusion
2.3. The Limits of Parallel Execution
2.3.1. Amdahl's Law
2.3.2. Universal Scalability Law
2.4. Reacting to Failure
2.4.1. Compartmentalization and Bulkheading
2.4.2. Using Circuit Breakers
2.4.3. Supervision
2.5. Losing Strong Consistency
2.5.1. ACID 2.0
2.5.2. Accepting Updates
2.6. The Need for Reactive Design Patterns
2.6.1. Managing Complexity
2.6.2. Bringing Programming Models Closer to the Real World
2.7. Summary
3. Tools of the Trade
3.1. Early Reactive Solutions
3.2. Functional Programming
3.2.1. Immutability
3.2.2. Side Effects
3.2.3. Referential Transparency
3.2.4. Functions as First-Class Citizens
3.3. Responsiveness to Users
3.3.1. Prioritizing the Three Performance Characteristics
3.4. Implementations That Support Reactive
3.4.1. Green Threads
3.4.2. Event Loops
3.4.3. Communicating Sequential Processes
3.4.4. Futures and Promises
3.4.5. Reactive Extensions
3.4.6. The Actor Model
3.4.7. Summary
Part 2: The Philosophy in a Nutshell
4. Message Passing
4.1. Messages
4.2. Vertical Scalability
4.3. Event-Based vs. Message-Based
4.4. Synchronous vs. Asynchronous
4.5. Flow Control
4.6. Delivery Guarantees
4.7. Vertical Scalability
4.8. Events as Messages
4.9. Synchronous Message Passing
4.10. Summary
5. Location Transparency
5.1. What is Location Transparency?
5.2. The Fallacy of Transparent Remoting
5.3. Explicit Message Passing to the Rescue
5.4. The Role of Latency and Throughput
5.5. The Role of Message Loss
5.6. Horizontal Scalability
5.7. Location Transparency makes Testing Simpler
5.8. Dynamic Composition
5.9. Summary
6. Divide and Conquer
6.1. Hierarchical Problem Decomposition
6.1.1. Defining the hierarchy
6.2. Dependencies vs. Descendant Modules
6.2.1. Avoiding the matrix
6.3. Advantages for Specification and Test
6.4. Build your own Big Corporation
6.5. Horizontal and Vertical Scalability
6.6. Summary
7. Principled Failure Handling
7.1. Ownership means Commitment
7.2. Ownership implies Lifecycle Control
7.3. Resilience on All Levels
7.4. Summary
8. Delimited Consistency
8.1. Encapsulated Modules to the Rescue
8.2. Grouping Data and Behavior According to Transaction Boundaries
8.3. Modeling Work-flows across Transactional Boundaries
8.4. Unit of Failure = Unit of Consistency
8.5. Segregation of Responsibilities
8.6. Persisting Isolated Scopes of Consistency
8.7. Summary
9. Non-Determinism by Need
9.1. Logic Programming and Declarative Data-Flow
9.2. Functional Reactive Programming
9.3. Shared-Nothing Concurrency
9.4. Shared-State Concurrency
9.5. So, What Should We Do?
9.6. Summary
10. Message Flow
10.1. Push Data Forward
10.2. Model the Processes of Your Domain
10.3. Identify Resilience Limitations
10.4. Estimate Rates and Deployment Scale
10.5. Plan for Flow Control
10.6. Summary for Part 2
Part 3: Patterns
11. Testing Reactive Applications
11.1. How To Test
11.1.1. Unit Tests
11.1.2. Component Tests
11.1.3. String Tests
11.1.4. Integration Tests
11.1.5. User Acceptance Tests
11.1.6. Black Box Versus White Box Tests
11.2. Test Environment
11.3. Testing Asynchronously
11.3.1. Providing Blocking Message Receivers
11.3.2. The Crux with Choosing Timeouts
11.3.3. Asserting the Absence of a Message
11.3.4. Providing Synchronous Execution Engines
11.3.5. Asynchronous Assertions
11.3.6. Fully Asynchronous Tests
11.3.7. Asserting the Absence of Asynchronous Errors
11.4. Testing Non-Deterministic Systems
11.4.1. The Trouble with Execution Schedules
11.4.2. Testing Distributed Components
11.4.3. Mocking Actors
11.4.4. Distributed Components
11.5. Testing Elasticity
11.6. Testing Resilience
11.6.1. Application Resilience
11.6.2. Infrastructure Resilience
11.7. Testing Responsiveness
11.8. Summary
12. Fault Tolerance and Recovery Patterns
12.1. The Simple Component Pattern
12.1.1. The Problem Setting
12.1.2. Applying the Pattern
12.1.3. The Pattern Revisited
12.1.4. Applicability
12.2. The Error Kernel Pattern
12.2.1. The Problem Setting
12.2.2. Applying the Pattern
12.2.3. The Pattern Revisited
12.2.4. Applicability
12.3. The Let-It-Crash Pattern
12.3.1. The Problem Setting
12.3.2. Applying the Pattern
12.3.3. The Pattern Revisited
12.3.4. Implementation Considerations
12.3.5. Corollary: the Heartbeat Pattern
12.3.6. Corollary: The Proactive Failure Signal Pattern
12.4. The Circuit Breaker Pattern
12.4.1. The Problem Setting
12.4.2. Applying The Pattern
12.4.3. The Pattern Revisited
12.4.4. Applicability
12.5. Summary
13. Replication Patterns
13.1. The Active—Passive Replication Pattern
13.1.1. The Problem Setting
13.1.2. Applying The Pattern
13.1.3. The Pattern Revisited
13.1.4. Applicability
13.2. Multiple-Master Replication Patterns
13.2.1. Consensus-Based Replication
13.2.2. Replication with Conflict Detection and Resolution
13.2.3. Conflict-Free Replicated Data Types
13.3. The Active—Active Replication Pattern
13.3.1. The Problem Setting
13.3.2. Applying The Pattern
13.3.3. The Pattern Revisited
13.3.4. The Relation to Virtual Synchrony
13.4. Summary
14. Resource Management Patterns
14.1. Resource Encapsulation Pattern
14.1.1. The Problem Setting
14.1.2. Applying the Pattern
14.1.3. The Pattern Revisited
14.1.4. Applicability
14.2. Resource Loan Pattern
14.2.1. The Problem Setting
14.2.2. Applying the Pattern
14.2.3. The Pattern Revisited
14.2.4. Applicability
14.2.5. Implementation Considerations
14.2.6. Variant: using the Resource Loan pattern for partial exposure
14.3. The Complex Command Pattern
14.3.1. The Problem Setting
14.3.2. Applying the Pattern
14.3.3. The Pattern Revisited
14.3.4. Applicability
14.4. The Resource Pool Pattern
14.4.1. The Problem Setting
14.4.2. Applying the Pattern
14.4.3. The Pattern Revisited
14.4.4. Implementation Considerations
14.5. Patterns for Managed Blocking
14.5.1. The Problem Setting
14.5.2. Applying the Pattern
14.5.3. The Pattern Revisited
14.5.4. Applicability
14.6. Summary
15. Message Flow Patterns
15.1. The Request—Response Pattern
15.1.1. The Problem Setting
15.1.2. Applying the Pattern
15.1.3. Common Instances of the Pattern
15.1.4. The Pattern Revisited
15.1.5. Applicability
15.2. The Self-Contained Message Pattern
15.2.1. The Problem Setting
15.2.2. Applying the Pattern
15.2.3. The Pattern Revisited
15.2.4. Applicability
15.3. The Ask Pattern
15.3.1. The Problem Setting
15.3.2. Applying the Pattern
15.3.3. The Pattern Revisited
15.3.4. Applicability
15.4. The Forward Flow Pattern
15.4.1. The Problem Setting
15.4.2. Applying the Pattern
15.4.3. The Pattern Revisited
15.4.4. Applicability
15.5. The Aggregator Pattern
15.5.1. The Problem Setting
15.5.2. Applying the Pattern
15.5.3. The Pattern Revisited
15.5.4. Applicability
15.6. The Saga Pattern
15.6.1. The Problem Setting
15.6.2. Applying the Pattern
15.6.3. The Pattern Revisited
15.6.4. Applicability
15.7. The Business Handshake Pattern
15.7.1. The Problem Setting
15.7.2. Applying the Pattern
15.7.3. The Pattern Revisited
15.7.4. Applicability
15.8. Summary
16. Flow Control Patterns
16.1. The Pull Pattern
16.1.1. The Problem Setting
16.1.2. Applying the Pattern
16.1.3. The Pattern Revisited
16.1.4. Applicability
16.2. The Managed Queue Pattern
16.2.1. The Problem Setting
16.2.2. Applying the Pattern
16.2.3. The Pattern Revisited
16.2.4. Applicability
16.3. The Drop Pattern
16.3.1. The Problem Setting
16.3.2. Applying the Pattern
16.3.3. The Pattern Revisited
16.3.4. Applicability
16.4. The Throttling Pattern
16.4.1. The Problem Setting
16.4.2. Applying the Pattern
16.4.3. The Pattern Revisited
16.5. Summary
17. State Management and Persistence Patterns
17.1. The Domain Object Pattern
17.1.1. The Problem Setting
17.1.2. Applying the Pattern
17.1.3. The Pattern Revisited
17.2. The Sharding Pattern
17.2.1. The Problem Setting
17.2.2. Applying the Pattern
17.2.3. The Pattern Revisited
17.2.4. Important Caveat
17.3. The Event-Sourcing Pattern
17.3.1. The Problem Setting
17.3.2. Applying the Pattern
17.3.3. Revisiting the Pattern
17.3.4. Applicability
17.4. The Event Stream Pattern
17.4.1. The Problem Setting
17.4.2. Applying the Pattern
17.4.3. The Pattern Revisited
17.4.4. Applicability
17.5. Summary
Appendixes
Appendix A: Diagramming Reactive Systems
A.1. Defining the Stencils
Appendix B: An Illustrated Example
B.1. Geographic Partitioning
B.2. Planning the Flow of Information
B.2.1. First Step: Accepting the Data
B.2.2. Second Step: Getting the Data to their Geographical Home
B.2.3. Step Three: Relocating the Data for Efficient Querying
B.2.4. Taking Stock
B.3. What if something fails?
B.3.1. A Client Fails
B.3.2. A Client Network Link Fails
B.3.3. A Data Ingestion Front-End Node Fails
B.3.4. A Network Link from Data Ingestion to Map Tile Fails
B.3.5. A Map Tile Processing Node Fails
B.3.6. A Summary Map Tile Fails
B.3.7. A Network Link between Map Tiles Fails
B.3.8. A Map View Front-End Node Fails
B.3.9. Failure Handling Summary
B.4. What have we learnt from this example?
B.5. Where do we go from here?
Appendix C: The Reactive Manifesto
C.1. Main text
C.2. Glossary
C.2.1. Asynchronous
C.2.2. Back-Pressure
C.2.3. Batching
C.2.4. Component
C.2.5. Delegation
C.2.6. Elasticity (in contrast to Scalability)
C.2.7. Failure (in contrast to Error)
C.2.8. Isolation (and Containment)
C.2.9. Location Transparency
C.2.10. Message-Driven (in contrast to Event-Driven)
C.2.11. Non-Blocking
C.2.12. Protocol
C.2.13. Replication
C.2.14. Resource
C.2.15. Scalability
C.2.16. System
C.2.17. User
About the Technology
Modern web applications serve potentially vast numbers of users - and they need to keep working as servers fail and new ones come online, users overwhelm limited resources, and information is distributed globally. A Reactive application adjusts to partial failures and varying loads, remaining responsive in an ever-changing distributed environment. The secret is message-driven architecture - and design patterns to organize it.
About the book
Reactive Design Patterns presents the principles, patterns, and best practices of Reactive application design. You'll learn how to keep one slow component from bogging down others with the Circuit Breaker pattern, how to shepherd a many-staged transaction to completion with the Saga pattern, how to divide datasets by Sharding, and more. You'll even see how to keep your source code readable and the system testable despite many potential interactions and points of failure.
What's inside
- The definitive guide to the Reactive Manifesto
- Patterns for flow control, delimited consistency, fault tolerance, and much more
- Hard-won lessons about what doesn't work
- Architectures that scale under tremendous load
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If the 'Reactive Manifesto' gave us a battle cry, this work gives us the strategic handbook for battle.
An engaging tour of distributed computing and the building blocks of responsive, resilient software.
This book is so reactive, it belongs on the left-hand side of the periodic table!