Introduction to Microservices and APIs

Overview

• Microservices: Services invoked remotely over the internet, providing access to data and services without needing to host them locally.
• APIs (Application Programming Interfaces): Also known as microservices; provide lightweight services available via simple interfaces and protocols over the internet.
• Use Cases: Message sending, text translation, streaming service searches, accessing COVID-19 data, airline timetables, geographic data, food nutrition data, weather data, etc.
• Internal Use: Companies like Facebook and Twitter use microservices internally to manage various functionalities.

What is an API?

• Functions called remotely over the internet, akin to local function calls but executed on different machines.
• Example: A client program calls an 'add' function that sends parameters over the internet to a server, which computes the result and sends it back.
• Communication: Standard web protocols like HTTP are used to package parameters and results.
  • HTTP Methods: GET, POST
  • Data Formats: JSON (JavaScript Object Notation) and XML (Extensible Markup Language)

JSON and XML

• JSON:
  • Syntax used in JavaScript for representing objects (similar to Python dictionaries).
  • Key-value pairs structure, can represent any JavaScript data structure.
  • Simple text format, easy to transport over the internet.
• XML:
  • More complex than JSON, can be extended using a schema.
  • Describes data structures in a structured text format.
  • Independent of programming languages.

Public Microservices and API Aggregators

• API Aggregators: Provide access to many microservices, making it easier to search and experiment with APIs.
  • Example: RapidAPI, offers documentation and gateways to APIs (free and paid accounts available).

Accessing Microservices with Python

• Python’s support for HTTP protocols makes it easy to access microservices.
• Example: Using OpenWeatherMap API to get weather data.
  • Requires API key and structured URL with city name and country code.

Example Code: Fetching Weather Data

import requests
import json
from apikey import API_key

url = "http://api.openweathermap.org/data/2.5/weather?q=Sydney,AU&appid=" + API_key
response = requests.get(url)
weather_data = json.loads(response.text)
print(weather_data)

Building Your Own Microservice with Python

• Framework: Bottle, a simple web framework for Python.
• Steps:
  1. Install Bottle module.
  2. Define endpoint using decorators.
  3. Write function to handle requests and return results.
  4. Run Bottle server.

Example Code: Bottle Microservice

Server Code

from bottle import route, run
import json

@route('/add/<a:int>/<b:int>')
def add(a, b):
    result = {'sum': a + b}
    return json.dumps(result)

run(host='localhost', port=8080)

Client Code

import requests
import json

url = "http://localhost:8080/add/1/2"
response = requests.get(url)
result = json.loads(response.text)
print(result)

Scalability and Cloud Services

• Scalability Concerns: Simple web servers like Bottle are not scalable for large numbers of clients.
• Cloud Solutions: AWS Lambda, API Gateway, etc., provide scalable cloud functions.

Conclusion

• Microservices and APIs are integral to modern internet systems, providing scalable and maintainable solutions for various functionalities.
• Available in many forms, both through public access and cloud services, making it easier to implement and manage.

Example Aggregators: RapidAPI