The integration framework Apache Camel provides a set of components integrating Debezium (Postgres and other connectors) with Apache Camel. This example demonstrates a sample application (A Q&A site, inspired by StackOverflow) and an integration pipeline capturing changes in the database generated by the application.
The example consists of multiple components:
- application accepting REST calls representing questions and answers to the questions
- PostgreSQL database to which the application writes the questions and answers
- MailHog test SMTP server
- Apache Camel pipeline that
- captures database changes
- converts the raw changes into domain Java classes
- creates an aggregate object from answers and associated question using Infinispan-based message store
- sends an email to author for every question created
- sends an email to the author of the question and author of the answer for every answer created
- when a question has three answers a message is sent to a Twitter timeline
Build the application and the pipeline and start PostgreSQL instance and MailHog server by running:
# Terminal One
$ mvn clean package
Start the deloyment (you need a Twitter developer account)
$ env TWITTER_CONSUMER_KEY=<...> TWITTER_CONSUMER_SECRET=<...> TWITTER_ACCESS_TOKEN=<...> TWITTER_ACCESS_TOKEN_SECRET=<...> docker-compose up
Create a question and three answers to it
# Terminal Two
$ curl -v -X POST -H 'Content-Type: application/json' http://0.0.0.0:8080/question/ -d @src/test/resources/messages/create-question.json
$ curl -v -X POST -H 'Content-Type: application/json' http://0.0.0.0:8080/question/1/answer -d @src/test/resources/messages/create-answer1.json
$ curl -v -X POST -H 'Content-Type: application/json' http://0.0.0.0:8080/question/1/answer -d @src/test/resources/messages/create-answer2.json
$ curl -v -X POST -H 'Content-Type: application/json' http://0.0.0.0:8080/question/1/answer -d @src/test/resources/messages/create-answer3.json
Check the emails sent in MailHog UI (http://localhost:8025/) in browser - four emails should be visible and your Twitter account should containe a message like Question 'How many legs does a dog have?' has many answers (...).