axon-multi
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Published
20 hours ago •
gushakov
gushakov
Playground application demonstrating DDD, EDA, CQRS with Axon
Axon Multi-services
:construction: Attention: under construction :construction:
:warning: Note, in AssignPrivateAddressSaga.java there is a use of QueryGateway for validation
of the address assigment. This goes against CQRS principles stating that a Saga must not access
the read-model (or projections). See this question and answer
for more details.
Introduction
Playground application with uses Axon framework to demonstrates a way of building a distributed event-driven system around the concepts of domain-driven design and CQRS.
Application structure
There are several modules, they are standalone Spring Boot applications or libraries:
-
common: module containing configuration (Maven dependencies) common to other modules -
core: module with all commands and events shared by other modules -
db: H2 file database running as a TCP server -
address: microservice around "address" aggregate -
person: microservice around "person" aggregate -
saga: Saga implementation of a business transaction (private address assignment)
Axon configuration
- Using Axon Server version 4.1 without event sourcing infrastructure
- Aggregates, projections, and Sagas persist their states in the separate schemas of the central H2 database
CQRS and messaging infrastructure
This is the overview of the system:
API
- http://localhost:8080/swagger-ui.html (Person)
- http://localhost:8081/swagger-ui.html (Address)
Saga
This is how assigning private address to a person Saga proceeds:
Build and run with Docker
- Run
mvn packageon the project - Run
docker-compose up
H2 database
- Access H2 console at http://localhost:8079/h2-console
- Use Server configuration
- JDBC URL: jdbc:h2:tcp://localhost:9090/./axondb;IFEXISTS=true;DB_CLOSE_ON_EXIT=FALSE
gushakov