Summary

Why use APIs?

• You already use it in daily internet browsing!
• Accessing data
• Analysis Services (e.g., translation api)

How the internet works

• YouTube playlist from Code.org
• Protocols (http)
• An API (application programming interface) is how applications talk to each other on the internet

Requests vs Responses

• Client (e.g., your phone, your computer, some other device) sends a request
• Server (e.g., data service, cloud service) sends a response
  • Response will contain a status code (see list)

Two Types of Requests

• GET: Get data
  • Parameters are included in URL
• POST: Modify data
  • Parameters are included in request body

What's inside of a POST request

• JSON: Contains key-value pairs
• Header: Parameters that are consistent each time you send a request (e.g., authentication information)
• Body: Parameters that change based on what you need.

Demos

• Local API
  • Postman: Great for demos. Not required for development.
  • R: httr, jsonlite, r lists
• Public APIs
  • Documentation
    • URL
    • GET vs POST
    • parameters (what goes into header vs body)
    • authentication
    • usage limits

Activity

• Find a Public API and its documentation (preferably no authentication required)
  • Try to connect to it using R
  • A few demos afterwards of ones that don't require authentication

Other considerations

• Authentication tokens: Don't share them and keep them safe!
• Webscraping: Not always legal. There's a reason some sites don't offer data through APIs.
• Security: If you are loading data to a service, make sure it doesn't contain PHI/PII.