Webhooks

Table of Contents

• Why?
• Webhook
• Visual Flow
• Step-by-Step Flow
• Implementation Details

Why?

• your server keeps asking did anything changed x3 every few seconds to other server.
• every few seconds.
• (in polling)
• its waste of resources.

Webhook

• flips this, the provider tells you whenever something is changed.
• you just give a URL ← it sends a HTTP POST.

Flow

Step 1

Register your webhook URL. (to any service Shopify)

Step 2

Event occur on the service → step 3 (a order gets registered)

Step 3

Server (service) sends a HTTP POST to your URL.

• also sends a signature header for verification.

Crucial Step 4

Respond with a HTTP 200 fast, schedule job for processing data, as if not responded fast it will try again.

In b/w of responding back you have to do step 5 (verify).

Step 5

• anyone on internet can POST to your URL.
• always verify signature.
• using webhook secret.

Implementation Details

• we saw, as parsing changes the bytes. (express.json() × on.raw)
• so you get original HMAC Buffer Verification.