Building Modern Business Applications: Reactive Cloud Architecture for Java, Spring, and PostgreSQL

Table of Contents
About the Author
About the Technical Reviewer
Acknowledgments
Introduction
Chapter 1: What Is a Business Application?
	Business Software
	Domain Specific
	How It Is Used
	Measuring Importance
	“Modern”
	Summary
Chapter 2: The Status Quo (and How It Came to Be)
	Business Application Architectures
		The Status Quo
		Green Screen
		Rich Client
		Web Applications
		The Rise of Consumer Applications
	Concurrent Practices
		Agile
		Test-Driven Development
		Continuous Integration and Delivery
		Observability
	Summary
Chapter 3: What Is a Reactive System?
	What Is Reactive?
	Reactive Manifesto
		Responsive
		Resilient
		Elastic
		Message Driven
	Composing a Reactive System
	Summary
Chapter 4: Why Build Business Applications As Reactive Systems?
	Business Expectations
	Developer Expectations
	Property Alignment
		Responsive
		Resilient
		Elastic
		Message Driven
	Summary
Chapter 5: What Is a Business Rule?
	Thinking About Business Rules
	Categorizations
		Data at Rest
		Side Effects
		Derivable Data
	Summary
Chapter 6: Managing Time
	Answering “What Happened?”
	Tracking Changes
	Why Did That Happen?
	Events
	Commands
	Understanding Time
	Serialization of Time
	Eventual Consistency
	Bitemporality
	Business Rule Changes
	Summary
Chapter 7: Constraints and Principles
	Constraints
		From REST to a Graph
		Falcor
		GraphQL
		Why GraphQL
		Being Real-Time
	Principles
		Never Forget
		Message Driven
		Read/Write Separation
		Partial Availability
		Design Flexibility
		Modularity
		Testability
		Amenability to Change
	Summary
Chapter 8: High-Level Data Flow
	Event Sourcing and CQRS
	Thinking in GraphQL Schemas
		Scalars and Enums
		Objects
		Lists
		Input Objects
		Interfaces and Unions
		Queries and Subscriptions
		Mutations
	Combining GraphQL + ES + CQRS
	Summary
Chapter 9: Command Processor
	What It Is, and Is Not
	Requirements
	Composing the Core Loop
	Handling Failures
		Infrastructure
		Application
		Enforcing Business Rules
	How to Test
		Testing the Command Processor
		Testing Your Code
	Summary
Chapter 10: Command Generator
	Interaction with GraphQL
		From Input Arguments into a Command
		Appending to the Command Log
		Returning the Mutation Result
	Commands and Other Required Data
	Handling Failures
		Optimistic Locking
		Timeouts
	Testing the Command Generator
		Command Submission
		Command Creation
	Summary
Chapter 11: Event Materializer
	Defining the View Model
	Event Materializer Behavior
		Transactions
		Consistency
		Multiple Sources
	Evolving the View Model
	Communicating Changes to Others
		GraphQL Subscriptions
		Other Side Effects
	Managing Failure
	Testing
	Summary
Chapter 12: Testing, Monitoring, and Observability
	Key Components
		Command Processor
		Command Generator
		Event Materializer
		Composed Data Flow
	Testing the Composed System
	Introducing Property-Based Testing
	Using Property-Based Testing
	Using Example Tests
	Observability
	Monitoring Production Systems
	Practice Using Tools
	Summary
Chapter 13: Required Technologies
	Design Review
	Constraints and Principles Recap
		GraphQL
		Real-Time Updates
		Never Forget
		Message Driven
		Read/Write Separation
		Partial Availability
		Design Flexibility
		Modularity
		Testability
		Amenability to Change
	Required Technologies
		Append-Only Log
		Pub/Sub Messaging
		Distributed Locking
		Database
	Summary
Chapter 14: Building with Modern Spring, Java, and PostgreSQL
	Required Technologies via PostgreSQL
		Advisory Locks
		LISTEN and NOTIFY
			NOTIFY
			LISTEN
		Schemas
		Append-Only Log
	Java and the JVM
	GraphQL-Java
	Spring Boot
	Project Reactor
	R2DBC
	jqwik
	Putting It All Together
	Summary
Chapter 15: Expansion Points and Beyond
	Design Flexibility and Amenability to Change
	Multiple Command Processors
	Command Processor State Caching
	Parallel Event Materialization
	Command and Event Logs As GraphQL Subscriptions
	Using GraphQL for Inter-Process Communication
	Federated GraphQL
	Outsourcing Distributed System Problems
	Bitemporal Materialized Views
	Conclusion
Index