This folder contains services written in Java that connect to Apache Kafka as means of communication between the services.
Tech stack:
- Java 8
- Spring Boot 1.5.x
- Spring Cloud Streams
- Apache Kafka
For the workflow engine you can decide between:
- Camunda (folder *-camunda)
- Zeebe (folder *-zeebe)
You can either
- Docker Compose with pre-built images from Docker Hub (simplest)
- Build (Maven) and start via Docker Compose
- Build (Maven) and start manually (including Zookeeper, Kafka)
The default is that Camunda is used in these settings. When you want to use Zeebe you have to manually build and run it.
For Camunda there is an enterprise edition available with [https://camunda.com/products/cockpit/#/features](additional features in Cockpit) (the monitoring tool). It is quite handy to use this when playing around with the example. You can easily switch to use enterprise edition:
- Get a trial license if you don't have a license yet: https://camunda.com/download/enterprise/
- Adjust Camunda version used in pom (order and payment use Camunda): ./order-camunda/pom.xml#L19, ./order-camunda/pom.xml#L69, ./payment-camunda/pom.xml#L13 and ./payment-camunda/pom.xml#L63
- Note that this only works if you build the projects locally, not with the pre-build images
Note that you do not need the enterprise edition to run the examples, the community edition will also do fine, you just cannot see and do that much in Camunda Cockpit.
- Download docker-dist/docker-compose.yml or clone the source code
- Goto directory where you downloaded this file
cd docker-dist
- Start using docker compose:
docker-compose up
- After everything has started up you are ready to visit the overview page http://localhost:8099
- You can place an order via http://localhost:8090
- You can inspect insided of Order via http://localhost:8091
- You can inspect insides of Payment via http://localhost:8092
- You can inspect all events going on via http://localhost:8095
If you like you can connect to Kafka from your local Docker host machine too. Because of so called advertised endpoints you have to map the Kafka container hostname to localhost. This is because the cluster manager of Kafka (Zookeeper) gives you his view of the Kafka cluster which containes of this hostname, even if you connected to localhost in the first place.
For example, on Windows append this entry to C:\Windows\System32\drivers\etc\hosts:
127.0.0.1 kafkaserver
On Linux edit the /etc/hosts accordingly.
- Download or clone the source code
- Run a full maven build
mvn install
- Build Docker images and start them up
docker-compose build
docker-compose up
- After everything has started up you are ready to visit the overview page http://localhost:8099
- You can place an order via http://localhost:8090
- You can inspect insided of Order via http://localhost:8091
- You can inspect insides of Payment via http://localhost:8092
- You can inspect all events going on via http://localhost:8095
If you like you can connect to Kafka from your local Docker host machine too. Because of so called advertised endpoints you have to map the Kafka container hostname to localhost. This is because the cluster manager of Kafka (Zookeeper) gives you his view of the Kafka cluster which containes of this hostname, even if you connected to localhost in the first place.
For example, on Windows append this entry to C:\Windows\System32\drivers\etc\hosts:
127.0.0.1 kafkaserver
On Linix edit the /etc/hosts accordingly.
- Download or clone the source code
- Run a full maven build
mvn install
- Install and start Kafka on the standard port
- Create topic "flowing-retail"
kafka-topics.sh --create --zookeeper localhost:2181 --replication-factor 1 --partitions 1 --topic flowing-retail
- You can check & query all topics by:
kafka-topics.sh --list --zookeeper localhost:2181
- Start the different microservices components by Spring Boot one by one, e.g.
mvn -f checkout exec:java
mvn -f order-camunda exec:java
...
Here you could easily switch to use order-zeebe instead. In this case make sure that you startup your Zeebe broker and create the default-topic first as described in Install Zeebe.
You can also import the projects into your favorite IDE and start the following class yourself:
checkout/io.flowing.retail.java.CheckoutApplication
...
- Now you can place an order via http://localhost:8090
- You can inspect insided of Order via http://localhost:8091
- You can inspect insides of Payment via http://localhost:8092
- You can inspect all events going on via http://localhost:8095