This example consists of two applications:
- Producer App:
- Publish messages using a Spring Messaging approach
- Store and retrieve information using Spring Data CrudRepository
- Implements a Workflow with Dapr Workflows
- Consumer App:
- Subscribe to messages
To run these examples you will need:
- Java SDK
- Maven
- Docker or a container runtime such as Podman
From the spring-boot-examples/
directory you can start each service using the test configuration that uses
Testcontainers to boostrap Dapr by running the following command:
cd producer-app/
../../mvnw -Dspring-boot.run.arguments="--reuse=true" spring-boot:test-run
This will start the producer-app
with Dapr services and the infrastructure needed by the application to run,
in this case RabbitMQ and PostgreSQL. The producer-app
starts on port 8080
by default.
The -Dspring-boot.run.arguments="--reuse=true"
flag helps the application to connect to an existing shared
infrastructure if it already exists. For development purposes, and to connect both applications we will set the flag
in both. For more details check the DaprTestContainersConfig.java
classes in both, the producer-app
and the consumer-app
.
Then run in a different terminal:
cd consumer-app/
../../mvnw -Dspring-boot.run.arguments="--reuse=true" spring-boot:test-run
The consumer-app
starts in port 8081
by default.
Now that both applications are up you can place an order by sending a POST request to :8080/orders/
You can use curl
to send a POST request to the producer-app
:
curl -X POST localhost:8080/orders -H 'Content-Type: application/json' -d '{ "item": "the mars volta EP", "amount": 1 }'
If you check the producer-app
logs you should see the following lines:
...
Storing Order: Order{id='null', item='the mars volta EP', amount=1}
Publishing Order Event: Order{id='d4f8ea15-b774-441e-bcd2-7a4208a80bec', item='the mars volta EP', amount=1}
If you check the consumer-app
logs you should see the following lines, showing that the message
published by the producer-app
was correctly consumed by the consumer-app
:
Order Event Received: Order{id='d4f8ea15-b774-441e-bcd2-7a4208a80bec', item='the mars volta EP', amount=1}
Next, you can create a new customer to trigger the customer's tracking workflow:
curl -X POST localhost:8080/customers -H 'Content-Type: application/json' -d '{ "customerName": "salaboy" }'
A new Workflow Instance was created to track the customers interactions. Now, the workflow instance is waiting for the customer to request a follow-up.
You should see in the producer-app
logs:
Workflow instance <Workflow Instance Id> started
Let's register the customer: salaboy
Customer: salaboy registered.
Let's wait for the customer: salaboy to request a follow up.
Send an event simulating the customer request for a follow-up:
curl -X POST localhost:8080/customers/followup -H 'Content-Type: application/json' -d '{ "customerName": "salaboy" }'
In the producer-app
logs you should see that the workflow instance id moved forward to the Customer Follow Up activity:
Customer follow-up requested: salaboy
Let's book a follow up for the customer: salaboy
Customer: salaboy follow-up done.
Congratulations the customer: salaboy is happy!
You can run the same example on a Kubernetes cluster. Check the Kubernetes tutorial here.