HATEOAS Driven Rest Api - Microservice Architecture with Spring Cloud, Docker, Kafka and ELK.
This is a project structure.
All applications in the project are dockerized.
In the center of this schema, you can see Eureka Discovery Server from Spring Cloud Netflix and 2 Spring Boot microservices registered to this server. The first microservice is Restful CRUD API, and it is uses PostgreSQL as a database. The second microservice is a mail sending service, and it is uses MailHog for SMTP testing.
In addition to these, 2 microservices communicate with each other with Apache Kafka and Zookeeper. API service sends message to Kafka and mail sending service receives this message and sends it by e-mail.
Also, elastic stack used for log-analysis solution. Filebeats binds the dockerized container logs and ships these to ElasticSearch. Then, Kibana visualize these logs.
HATEOAS (Hypermedia as the Engine of Application State) is a constraint of the REST application architecture that lets us use the hypermedia links in the response contents. It allows the client can dynamically navigate to the appropriate resources by traversing the hypermedia links.
JSON Hypermedia API Language (HAL) is a response's content-type: application/hal+json with pagination.
All applications in this project are dockerized. To achieve this, 3 docker-compose files are created.
Then, all applications can be started with a single docker-compose command:
docker-compose -f docker-compose-app.yml -f docker-compose-elk.yml -f docker-compose-kafka.yml up --build -d
PS: For local development, up docker-compose-kafka-local.yml, then start microservices.
docker-compose -f docker-compose-kafka-local.yml up -d
JUnit5, Mockito and Github-Faker are used in this project.
This snippet shows that unit test for Get by id request and usage of Arrange-Act-Assert (3A) pattern. Additionally, checks status of response.
This snippet checks whether expected and returned objects are equal according to the fields.
This snippet checks whether invalid request returns the HTTP status 400 Bad Request.
Used Spring Actuator for health check.
http://localhost:8081/actuator/health
{ "status": "UP" }
Used PostgreSQL as database.
DB Diagram:
spring.datasource.initialization-mode:always for database initialization from schema.sql
Database Schema Generation - Sql: ./flight-booking-service/src/main/resources/schema.sql
Database Inserts - Sql: ./flight-booking-service/src/main/resources/db-inserts.sql`
BaseEntity class with @MappedSuperClass annotation and is used by all entity classes as a super class. BaseEntity consists of id, creationTimestamp, updateTimestamp and deletionTimestamp fields.
Additionally, there are ManyToOne and OneToMany relations between entities.
Kafka Producer in microservice 1(flight-booking-service), that sends the email message to Kafka.
Kafka Consumer in microservice 2(mail-service), that receives the published email message from Kafka and sends it by e-mail.
MailHog, that catches e-mail was sent by microservice 2(mail-service).
Additionally, this whole process can be monitored and analyzed through Kibana with Elasticsearch.
Docs located ./docs folder in the main project folder.
Used javadoc standards for method comments.
Run mvn javadoc:javadoc for create javadocs.
Used Swagger and Api-Docs for RestAPI endpoints.
http://localhost:8081/swagger-ui/index.html?configUrl=/api-docs/swagger-config
- MapStruct is used for mapping between DTOs.
- Lombok is used for autogenerate boilerplate zero-value codes.
Scenario 1: Create a new customer, create a new flight and customer books this flight
... TO DO ...
...
Flight Booking API is developed under the MIT License.
Görkem Taşçı, 2021
LinkedIn: https://www.linkedin.com/in/tascigorkem/