This a'la Enterprise Service Bus (ESB) service is a part of a project that required Service Oriented Architecture (SOA) implementation. We worked on a project in a group of four for a Master's class at the University of Aveiro. It demanded effective teamwork and communication skills.

• OAuth e.g. Login via Google / Github / Facebook are feasible to implement
• Contracts... In SOA, a contract defines the agreed-upon rules and expectations for service communication between providers and consumers.
• Cookie-Based Auth is vulnerable to CSRD attacks, next time use more modern approach featuring Edge Auth
• Consider using REST API instead of Queues when there is a need to reply-back
• Repository pattern: isolates persistence layer from the app very well
• Factory Pattern: When there is many of new Factories appearing, consider Abstract Factory for objects inheriting from the same parent class
• Parametrizing environment variables is a must approach when the app meets deployment. Never push hardcoded secrets.
• Authenticate, document and version REST API

• REST:GET/POST/PUT/DELETE
• "APIs are like resources"
• "The issue with REST is that the server always must reply back… Synchronous nature…"

1. Never use verbs, use nouns
   1. DO NOT: /getAllProducts
   2. DO: /products
2. Use plurals
   1. DO NOT: /product/all
   2. DO:/products
3. Use parameters
   1. DO NOT: /getProductsByName
   2. DO: /products?name=’ABC'
4. Use proper HTTP codes - there is more than 200, 403, 500, especially errors
5. Always version your APIs
   1. DO NOT: /products
   2. DO: /v1/products, later /v2/products
6. Use pagination (when you expose data to public and load balancing is done wrong)
   1. DO NOT: /products?limit=99999999
   2. DO: /products?limit=25&offset=50
7. Supported formats (mostly JSON or legacy XML)
8. Use OpenAPI specifications // documentation

• "No need to reply back"

1. Asynchronous
2. Reliable queuing
3. 1-to-1 interaction with failure resillience
4. 1-to-many interaction - improve performance, “the message reaches everyone”
5. many-to-many - as in replicated services for large amount of clients
6. Allow to implement complex interaction patterns
7. Flexibility at the cost of performance
8. Queues promote clustering

• Backend: FastAPI
• Auth: Auth0
• Middlewares: ActiveMQ, Kubernetes Traefik (Ingress)
• Persistence: MySQL