What methods are used to implement interaction between microservices in the system?

Interaction between microservices is usually implemented in the following ways:

1. Synchronous interaction via HTTP/REST API — microservices exchange requests and responses over HTTP protocol, using REST or GraphQL. This is a simple and common method, but it creates tight coupling and requires high availability of services.

2. Asynchronous interaction via message queues — microservices exchange messages through brokers (RabbitMQ, Kafka, Redis Streams). This increases resilience and scalability, as services do not depend on each other's immediate availability.

3. gRPC or other binary protocols — for more efficient and faster data exchange, especially within infrastructure.

4. Shared cache or database — sometimes services interact through shared storage, but this is less preferred due to weak isolation.

An example of a simple HTTP request between microservices in Python using the requests library:

import requests

response = requests.get('http://service-b/api/data')
if response.status_code == 200:
    data = response.json()
    print(data)

The choice of method depends on requirements for reliability, latency, and system architecture.