Lesson 2. API — How Services Communicate

Lesson 2. API — How Services Communicate#

Why This Matters#

API (Application Programming Interface) is the language programs use to talk to each other. Understanding APIs is important for setting up integrations.

Key Idea#

API = "translator" between services

One service sends a request, the other responds. For example, your bot sends a "write data" request to Google Sheets, and Sheets responds "done".

How API Works (Simple Analogy)#

Imagine a restaurant:

• Customer (your bot) wants to order food

• Waiter (API) takes the order and brings it to the kitchen

• Kitchen (the service, e.g., Google Sheets) prepares the order

• Waiter (API) brings the finished dish back

The API is the waiter who delivers your requests and brings back responses.

Types of API Requests#

GET — retrieve data

Example: "Show me the list of clients"

POST — send data

Example: "Add a new client"

PUT — update data

Example: "Change the client's phone number"

DELETE — delete data

Example: "Remove the client"

Real-World API Example#

Scenario: a bot records a client in Google Sheets

1. The bot sends a POST request to Google Sheets API:

   • "Write to the spreadsheet: name — Ivan, phone — +7-999-111-22-33"

2. Google Sheets receives the request, writes the data

3. Google Sheets responds: "Done, written to row 15"

4. The bot receives the response and tells the client: "I've recorded you!"

What You Need to Work with APIs#

1. URL (API address) — where to send requests

   Example: https://sheets.googleapis.com/v4/spreadsheets/...

2. Authorization key (API key or token) — so the API knows it's you

   Example: Bearer abc123xyz456

3. Request data — what to send

   Example: {"name": "Ivan", "phone": "+7-999-111-22-33"}

4. Data format — usually JSON (more on that next)

What to Know#

• Most modern services provide APIs

• You do NOT need to program — no-code platforms do it all for you

• API is the standard way to integrate in 2026

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