play-api.md

Get hands dirty

Let's play with some API. There is no better way to understand what API is other than playing with it and seeing it in action.

Prerequisites

You need some software installed first.

CLI

Install websocat to perform WebSocket request from your terminal

Browser

• Get Postman account to use Postman Workspaces
• Install Postman Desktop Agent to perform WebSocket requests

Play with WebSocket API from Kraken

WebSocat

1. Establish a connection with the API

   websocat wss://ws.kraken.com

2. Ping the API to see if it responds. Just type the below message and hit Enter:

   {"event": "ping"}

3. Now subscribe to the event ticker stream that sends messages with currency price. Just type the below message and hit Enter:

   {  "event": "subscribe",  "pair": [    "XBT/USD",    "XBT/EUR"  ],  "subscription": {    "name": "ticker"  }}

4. You should now see a constant stream of data sent by the server. You do not have to ask the API every second for an update, as the update is pushed to you.

5. Now unsubscribe from info about one currency pair. Just type the below message and hit Enter:

   {    "event": "unsubscribe",    "pair": [        "XBT/USD"    ],    "subscription": {        "name": "ticker"    }}

6. You should see a message that you unsubscribed and the rest of the stream is just about EUR

Postman

1. Go to this Postman Workspace with WebSocket APIs.
2. Right-click on the Kraken API collection located at the left side of the page (alternatively, you can click on the ... icon, which shows when you hover on Kraken API).
3. Select the Create a fork option from the list.
4. Go to your forked workspace and use the Kraken API collection to ping the server.
5. Use the Kraken API collection to send the subscribe and unsubscribe messages.