# Example of defining the boundaries and interfaces of a User microservice in Python using FastAPI

# user.py - User microservice

from fastapi import FastAPI

app = FastAPI()

@app.get("/users/{user_id}")
async def get_user(user_id: int):
    # Logic to fetch user data from database
    return {"user_id": user_id, "name": "John", "age": 30}

@app.post("/users")
async def create_user(user_data: dict):
    # Logic to create a new user in the database
    return {"user_id": 1, "name": user_data["name"], "age": user_data["age"]}

# Example of communication patterns between User and Order microservices using RESTful APIs in Node.js with Express

// user-service.js - User microservice

const express = require('express');
const app = express();

app.get('/users/:userId', (req, res) => {
  // Logic to fetch user data from database
  res.json({ userId: req.params.userId, name: 'John', age: 30 });
});

// order-service.js - Order microservice

const express = require('express');
const app = express();

app.post('/orders', (req, res) => {
  // Logic to create a new order in the database
  // and communicate with User microservice to fetch user data
  // Example of making API call to User microservice
  axios.get(`http://user-service/users/${req.body.userId}`)
    .then(response => {
      // Process user data and create order
      res.json({ orderId: 1, userId: req.body.userId, productName: req.body.productName });
    })
    .catch(error => {
      // Handle error
      res.status(500).json({ error: 'Failed to create order' });
    });
});

// Example of data management in microservices using a message queue (RabbitMQ) in Java with Spring Boot

// user-service - User microservice

@RestController
public class UserController {

  @Autowired
  private UserService userService;

  @GetMapping("/users/{userId}")
  public User getUser(@PathVariable("userId") int userId) {
    // Logic to fetch user data from database
    return userService.getUserById(userId);
  }
}

// order-service - Order microservice

@RestController
public class OrderController {

  @Autowired
  private OrderService orderService;

  @Autowired
  private RabbitTemplate rabbitTemplate;

  @PostMapping("/orders")
  public Order createOrder(@RequestBody OrderDto orderDto) {
    // Logic to create a new order in the database
    // Publish order data to RabbitMQ message queue for processing
    rabbitTemplate.convertAndSend("order-exchange", "order.create", orderDto);
    return orderService.createOrder(orderDto);
  }
}

@Component
public class OrderConsumer {

  @RabbitListener(queues = "order-queue")
  public void processOrder(OrderDto orderDto) {
    // Logic to process order data, communicate with User microservice, and create order
  }
}

# Example of deployment strategy using Docker Compose for a microservices architecture with multiple services

version: '3'
services:
  user-service:
    build: ./user-service
    ports:
      - "8001:8001"
    networks:
      - my-network
  order

# Example of installing Docker Engine on Ubuntu using Docker's official installation script

# Update package index
sudo apt update

# Install dependencies
sudo apt install apt-transport-https ca-certificates curl software-properties-common

# Add Docker repository
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/trusted.gpg.d/docker.gpg
sudo add-apt-repository "deb [arch=$(dpkg --print-architecture signed-by /etc/apt/trusted.gpg.d/docker.gpg)] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"

# Update package index again
sudo apt update

# Install Docker
sudo apt install docker-ce docker-ce-cli containerd.io

# Start and enable Docker service
sudo systemctl start docker
sudo systemctl enable docker

# Verify Docker installation
docker --version

# Example of Docker Compose configuration for local development and testing

version: '3'
services:
  user-service:
    build: ./user-service
    ports:
      - "8001:8001"
    networks:
      - my-network
  order-service:
    build: ./order-service
    ports:
      - "8002:8002"
    networks:
      - my-network

networks:
  my-network:

# Example of installing Kubernetes using Minikube for container orchestration

# Install dependencies
sudo apt update
sudo apt install curl

# Install kubectl
sudo snap install kubectl --classic

# Install Minikube
curl -LO https://storage.googleapis.com/minikube/releases/latest/minikube-linux-amd64
sudo install minikube-linux-amd64 /usr/local/bin/minikube

# Start Minikube cluster
minikube start

# Verify Kubernetes installation
kubectl version

# Monolithic code for an e-commerce application

def process_order(order):
    # Process order logic here
    # ...
    return result

def get_customer_info(customer_id):
    # Get customer info logic here
    # ...
    return customer_info

def calculate_shipping_cost(order):
    # Calculate shipping cost logic here
    # ...
    return shipping_cost

# Other functionalities...

# Microservice 1: Order Service

def process_order(order):
    # Process order logic here
    # ...
    return result

# Other functionalities specific to order service...

# Microservice 2: Customer Service

def get_customer_info(customer_id):
    # Get customer info logic here
    # ...
    return customer_info

# Other functionalities specific to customer service...

# Microservice 3: Shipping Service

def calculate_shipping_cost(order):
    # Calculate shipping cost logic here
    # ...
    return shipping_cost

# Other functionalities specific to shipping service...

# Each microservice is a separate module or application that can be developed, tested, and deployed independently.

# Dockerfile for Order Service microservice

# Use a base image
FROM python:3.9

# Set working directory
WORKDIR /app

# Copy source code into the container
COPY . .

# Install dependencies
RUN pip install --no-cache-dir -r requirements.txt

# Expose necessary ports
EXPOSE 8001

# Run the microservice
CMD ["python", "app.py"]

# Docker Compose configuration for local development and testing

version: '3'
services:
  order-service:
    build: ./order-service
    ports:
      - "8001:8001"
    networks:
      - my-network

# Other services and networks...

# Logstash configuration file

input {
  beats {
    port => 5044
  }
}

filter {
  # Filter logic here
}

output {
  elasticsearch {
    hosts => ["elasticsearch:9200"]
    index => "my-microservice-%{+YYYY.MM.dd}"
  }
}

// Log4j2 logging code in a Java microservice

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

public class MyMicroservice {
  private static final Logger LOGGER = LogManager.getLogger(MyMicroservice.class);

  public void processOrder(Order order) {
    // Process order logic here

    // Log an info level message
    LOGGER.info("Order processed successfully: {}", order);
  }
}

# Prometheus monitoring code in a Python microservice

from prometheus_client import Counter, start_http_server

# Define a counter for tracking order requests
ORDER_REQUESTS = Counter('order_requests_total', 'Total number of order requests')

def process_order(order):
    # Process order logic here

    # Increment the order requests counter
    ORDER_REQUESTS.inc()

    # ...

// Zipkin distributed tracing code in a Java microservice

import brave.Span;
import brave.Tracer;

public class MyMicroservice {
  private final Tracer tracer;

  public MyMicroservice(Tracer tracer) {
    this.tracer = tracer;
  }

  public void processOrder(Order order) {
    // Process order logic here

    // Start a new Zipkin span
    Span span = tracer.newTrace().name("processOrder").start();

    try {
      // ... Processing logic ...
    } finally {
      // End the Zipkin span
      span.finish();
    }
  }
}