This projects helps to build and deploy a microservice by applying DDD, CQRS, Event Souring principles on AXON JVM stack.

What you'll build

You'll build a sample microservice with one bounded context.

What you'll need

AXON stack - framework and server
Java
SpringBoot
Postgres

Learn more about AXON stack
AXON is a open source stack to develop java based microservices . https://axoniq.io

package structure

This stack requires you to architect/structure your code is a particular way.

api

This is where the core APIs live. APIs are exposed as command and queries which a client can use to interact with the system. This package also contains the Domain Events leveraged by commands and queries

command

This package contains model which serves the command side of application. These model serves the commands only.

query

This package contains model which serves the query side of application. These model serves the queries only.

client

This package contains a domain service for test purposes.

---

set up

For this DEMO, I am using the Event store which comes as part of AXON stack.

1. spin up the docker container instance of AXON server : docker run -it --rm --name axonserver -p 8024:8024 -p 8124:8124 axoniq/axonserver

Check AXON dasboard : http://localhost:8024/

2. spin up the docker container instance of postgres : docker run -it --rm --name postgres -p 5432:5432 -e POSTGRES_USER=planmatch -e POSTGRES_PASSWORD=secret postgres:9.6

---

run application

Run this as springboot app

---

verify

Check the console log to see your commands and queries in action.

2019-09-23 13:09:00.013 DEBUG 5200 --- [main] com.example.match.client.DomainService : issuing create command 2019-09-23 13:09:00.201 INFO 5200 --- [.match.query]-0] o.a.e.TrackingEventProcessor : Using current Thread for last segment worker: TrackingSegmentWorker{processor=com.example.match.query, segment=Segment[0/0]} 2019-09-23 13:09:00.213 INFO 5200 --- [.match.query]-0] o.a.e.TrackingEventProcessor : Fetched token: null for segment: Segment[0/0] 2019-09-23 13:09:00.225 INFO 5200 --- [.match.query]-0] o.a.a.c.event.axon.AxonServerEventStore : open stream: 0 Security framework of XStream not initialized, XStream is probably vulnerable. 2019-09-23 13:09:00.350 DEBUG 5200 --- [mmandReceiver-0] com.example.match.command.Inquiry : handling cmd InquiryCreateCommand(id=d6a323cc-fd78-425a-9825-a3032c6998b8, firstName=simar, status=create) 2019-09-23 13:09:00.355 DEBUG 5200 --- [mmandReceiver-0] com.example.match.command.Inquiry : applying evt InquiryCreatedEvent(id=d6a323cc-fd78-425a-9825-a3032c6998b8, firstName=simar, status=create) 2019-09-23 13:09:00.545 DEBUG 5200 --- [.match.query]-0] c.e.match.query.InquirySummaryProjector : projecting evt InquiryCreatedEvent(id=d6a323cc-fd78-425a-9825-a3032c6998b8, firstName=simar, status=create) 2019-09-23 13:09:00.570 DEBUG 5200 --- [main] com.example.match.client.DomainService : issuing score command 2019-09-23 13:09:00.619 DEBUG 5200 --- [mmandReceiver-1] com.example.match.command.Inquiry : applying evt InquiryCreatedEvent(id=d6a323cc-fd78-425a-9825-a3032c6998b8, firstName=simar, status=create) 2019-09-23 13:09:00.622 DEBUG 5200 --- [mmandReceiver-1] com.example.match.command.Inquiry : handling cmd InquiryScoreCommand(id=d6a323cc-fd78-425a-9825-a3032c6998b8, score=5, status=complete) 2019-09-23 13:09:00.623 DEBUG 5200 --- [mmandReceiver-1] com.example.match.command.Inquiry : applying evt InquiryScoredEvent(id=d6a323cc-fd78-425a-9825-a3032c6998b8, score=5, status=complete) 2019-09-23 13:09:00.644 DEBUG 5200 --- [.match.query]-0] c.e.match.query.InquirySummaryProjector : projecting evt InquiryScoredEvent(id=d6a323cc-fd78-425a-9825-a3032c6998b8, score=5, status=complete) 2019-09-23 13:09:00.660 DEBUG 5200 --- [main] com.example.match.client.DomainService : querying inquiry 2019-09-23 13:09:00.744 DEBUG 5200 --- [main] com.example.match.client.DomainService : inquiry queried InquirySummaryView(id=d6a323cc-fd78-425a-9825-a3032c6998b8, firstName=simar, initialState=create, currentState=complete, score=5)

              yuhu 

Some other tests will help gain better understanding. Try to issue command in following different scenarios.

1. firstName is 'invalid'
2. score is 0 or less

---

Summary

Congratulations on spinning up your microservices with AXON stack.

More information can be found here: https://medium.com/@bawa.simar/building-microservices-by-applying-ddd-cqrs-and-event-sourcing-on-axon-java-sprint-boot-platform-2e12289b8a2b