Axon Reference Guide
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4.5
Introduction
Architecture Overview
Axon Server
Release Notes
Getting Started
Quick Start
Axon Framework
Introduction
Messaging Concepts
Commands
Events
Queries
Sagas
Deadlines
Testing
Tuning
Monitoring and Metrics
Spring Boot Integration
Modules
Axon Server
Introduction
Installation
Administration
Security
Performance
Migration
Extensions
Spring AMQP
JGroups
Kafka
Kotlin
Mongo
Reactor
Spring Cloud
Tracing
Appendices
A. RDBMS Tuning
B. Message Handler Tuning
C. Meta Annotations
D. Identifier Generation
E. Axon Server Query Language
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D. Identifier Generation
The Axon Framework uses an IdentifierFactory to generate all identifiers, whether they are for events, commands or queries. The default IdentifierFactory uses randomly generated java.util.UUID based identifiers. Although they are very safe to use, the process to generate them does not excel in performance.
IdentifierFactory is an abstract factory that uses Java's ServiceLoader (since Java 6) mechanism to find the implementation to use. This means you can create your own implementation of the factory and put the name of the implementation in a file called /META-INF/services/org.axonframework.common.IdentifierFactory. Java's ServiceLoader mechanism will detect that file and attempt to create an instance of the class named inside.
There are a few requirements for the IdentifierFactory. The implementation must:
    1.
    Have its fully qualified class name as the contents of the /META-INF/services/org.axonframework.common.IdentifierFactory file on the classpath,
    2.
    have an accessible zero-argument constructor,
    3.
    extend IdentifierFactory,
    4.
    be accessible by the context classloader of the application or by the classloader that loaded the IdentifierFactory class, and must
    5.
    Be thread-safe.
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C. Meta Annotations
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E. Axon Server Query Language
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