Axon Reference Guide
AxonIQ
Download Axon
4.0
Introduction
Quick start
Architecture overview
Axon Server
Setting up
Prerequisites
Maven/Gradle dependencies
Spring Boot
Starting the Axon Server
Implementing domain logic
Command handling
Event handling
Query handling
Complex Business Transactions
Configuring Infrastructure components
Messaging concepts
Command processing
Event processing
Query processing
Deadlines
Operations Guide
Setting up Axon Server
Production considerations
Extensions
Spring AMQP
Kafka
JGroups
Spring Cloud
Mongo
Appendices
A. RDBMS Tuning
B. Message Handler Tuning
C. Meta Annotations
D. Identifier Generation
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D. Identifier Generation

Last updated last month

The Axon Framework uses an IdentifierFactory to generate all the 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.

Appendices - Previous
C. Meta Annotations