The Curator-Project – Architecture Backend

Before I’ll start with the code some thoughts what has to bee done and what is additional work.

Data structure

How should the content be structured to display it to the user? The easiest way is to implement something that feels like a folder structure for navigation and add tags to get some clusters.


  • The category entity should work like a folder-structure. It references one parent category entity and might have some sub/child-categories.
  • The media entity links to category to get something similar like a path. Media groups contain multiple documents. In this way for example an audio book with more then one file can be accomplished.
  • The document entity references a single file. The path might contain a file path as well as a reference to a S3.
  • The tag entity clusters the media independent on category or media-type. For example it could group all media with excavator (song, instruction, images, …)
  • The user entity represents a basic user. For now this will be real basic and will be moved in future to the authentication service.


The Frontend should communicate via REST with the Backend


To get an abstraction between the DB-Entities and the Rest-Endpoint we’ll implement some converters.

DTOs & Views

DTOs will act as a abstraction of an Entity. Views are an specialized object which might contain only a reduced set of an entity or a mix of several entities.


As productive and development database I’ll use PostgreSQL. The schema is created by JPA

    database-platform: org.hibernate.dialect.PostgreSQLDialect
    show-sql: true
    generate-ddl: true
      ddl-auto: create-drop
      hibernate.jdbc.time_zone: UTC
      hibernate.format_sql: true

The attribute ddl-auto: create-drop creates the schema and the tables for the entities. Liquibase or something similar would be a much better approach, but would take much more effort for now.


To get some initial data I’ll do this direct via Java. Like the setup of the DB schema technical it would be a much better approach to do this with Liquibase. The benefit of using the CRUD-Services is that these services can be tested on the bootup.


public class CategoryBootstrap { 
    public void init() {

Document storage

As storage I’ll use Minio which is fully compatible with S3. I’m using tobi312/minio because it works on my raspberry pi. Feel free to use a different container like minio/minio.

This part of my docker-compose-file shows the configuration. of the minio-service

    container_name: minio
    image: tobi312/minio:latest
    restart: always
    command: [ "server", "--address", ":9000", "--console-address", ":9001", "/data" ]
      MINIO_ROOT_USER: admin
      - "9000:9000"
      - "9001:9001"
      - "/opt/minio/data:/data:rw"
      test: [ "CMD", "curl", "--fail", "http://localhost:9000/minio/health/live" ]
      interval: 60s
      timeout: 10s
      retries: 3
      - curatornet