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Kin Python SDK

The Kin Python SDK enables developers use Kin inside their backend servers. It contains support for blockchain actions such as creating accounts and sending payments, as well a webhook handler class to assist with implementing Agora webhooks.

Requirements

Python 3.6 or higher

Installation

pip install kin-sdk-v2

Overview

The SDK contains two main components: the Client and the WebhookHandler. The Client is used for blockchain actions, such as creating accounts sending payments, while the WebhookHandler is meant for developers who wish to make use of Agora Webhooks. It is recommended that developers read the website documentation prior to using this SDK.

Client

The main component of this library is the Client class, which facilitates access to the Kin blockchain.

Initialization

At a minimum, the client needs to be instantiated with an Environment.

from agora.client import Client, Environment 

client = Client(Environment.TEST)

Apps with registered app indexes should initialize the client with their index:

from agora.client import Client, Environment

client = Client(Environment.TEST, app_index=1)

Usage

The following outlines some example usages of the client. See the documentation for more details.

Create an Account

The create_account method creates an account with the provided private key.

To create a new account, first generate a new private key, then submit it using create_account:

from agora.client import Client, Environment
from agora.keys import PrivateKey

client = Client(Environment.TEST, app_index=1)

private_key = PrivateKey.random()
client.create_account(private_key)

Get a Transaction

The get_transaction method gets transaction data by transaction id.

from agora.client import Client, Environment

client = Client(Environment.TEST, app_index=1)

# tx_id is either a 32-byte Stellar transaction hash or a 64-byte Solana transaction signature 
tx_id = b'<txid>'
transaction_data = client.get_transaction(tx_id)

Get an Account Balance

The get_balance method gets the balance of the provided account, in quarks.

from agora.keys import PrivateKey
from agora.client import Client, Environment

client = Client(Environment.TEST, app_index=1)
public_key = PrivateKey.random().public_key
balance = client.get_balance(public_key)

Submit a Payment

The submit_payment method submits the provided payment to Agora.

from agora.client import Client, Environment
from agora.keys import PrivateKey, PublicKey
from agora.model import Payment, TransactionType
from agora.utils import kin_to_quarks

client = Client(Environment.TEST, app_index=1)
sender = PrivateKey.from_string('SXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX')
dest = PublicKey.from_string('GXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX')
payment = Payment(sender, dest, TransactionType.EARN, kin_to_quarks("1"))

tx_hash = client.submit_payment(payment)

Submit an Earn Batch

The submit_earn_batch method submits a batch of earns to Agora from a single account. It batches the earns into fewer transactions where possible and submits as many transactions as necessary to submit all the earns.

from agora.client import Client, Environment
from agora.keys import PublicKey, PrivateKey
from agora.model import Earn, EarnBatch
from agora.utils import kin_to_quarks

client = Client(Environment.TEST, app_index=1)
sender = PrivateKey.from_string('SXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX')
dest1 = PublicKey.from_string('GXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX1')
dest2 = PublicKey.from_string('GXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX2')

# Send two earns of 1 Kin each
earns = [
    Earn(dest1, kin_to_quarks("1")),
    Earn(dest2, 100000),  # also equivalent to 1 Kin
    ...
]
batch = EarnBatch(sender, earns)

batch_earn_result = client.submit_earn_batch(batch)

Examples

A few examples for creating an account and different ways of submitting payments and batched earns can be found in examples/client.

Webhook Handler

The WebhookHandler class is designed to assist developers with implementing the Agora webhooks.

Only apps that have been assigned an app index can make use of Agora webhooks.

Initialization

The WebhookHandler must be instantiated with the app's configured webhook secret.

from agora.client import Environment
from agora.webhook.handler import WebhookHandler

webhook_handler = WebhookHandler(Environment.TEST, 'mysecret')

Usage

Currently, WebhookHandler contains support for the following webhooks:

Events Webhook

To use the WebhookHandler with the Events webhook, developers should define a function that accepts a list of events and processes them in some way:

from typing import List

from agora.webhook.events import Event


def process_events(events: List[Event]) -> None:
    # some processing logic
    return

This function can be used with WebhookHandler.handle_events inside your events endpoint logic as follows:

from typing import List

from agora.client import Environment
from agora.webhook import WebhookHandler, AGORA_HMAC_HEADER
from agora.webhook.events import Event

webhook_handler = WebhookHandler(Environment.TEST, 'mysecret')


def process_events(events: List[Event]) -> None:
    # some processing logic
    return


# This will vary depending on which framework is used.
def events_endpoint_func(request):
    status_code, request_body = webhook_handler.handle_events(
        process_events,
        request.headers.get(AGORA_HMAC_HEADER),
        request.body,
    )
    
    # respond using provided status_code and request_body  

Sign Transaction Webhook

The sign transaction webhook is used to sign Kin 3 transactions with a whitelisted Kin 3 account to remove fees. On Kin 4, the webhook can be used to simply approve or reject transactions submitted by mobile clients.

To use the WebhookHandler with the Sign Transaction webhook, developers should define a function that accepts a sign transaction request and response object and verifies the request in some way and modifies the response object as needed:

from agora.webhook.sign_transaction import SignTransactionRequest, SignTransactionResponse

def verify_request(req: SignTransactionRequest, resp: SignTransactionResponse) -> None:
    # verify the transaction inside `req`, and modify `resp` as needed.
    return

This function can be used with WebhookHandler.sign_transaction inside your sign transaction endpoint logic as follows:

from agora.client import Environment
from agora.webhook import WebhookHandler, AGORA_HMAC_HEADER
from agora.webhook.sign_transaction import SignTransactionRequest, SignTransactionResponse

webhook_handler = WebhookHandler(Environment.TEST, 'mysecret')

def verify_request(req: SignTransactionRequest, resp: SignTransactionResponse) -> None:
    # verify the transaction inside `req`, and modify `resp` as needed (e.g. by calling `sign`).
    return

# This will vary depending on which framework is used.
def sign_tx_endpoint_func(request):
    status_code, request_body = webhook_handler.handle_sign_transaction(
        verify_request,
        request.headers.get(AGORA_HMAC_HEADER),
        request.body,
    )
    
    # respond using provided status_code and request_body  

Example Code

A simple example Flask server implementing both the Events and Sign Transaction webhooks can be found in examples/webhook/app.py. To run it, first install all required dependencies (it is recommended that you use a virtual environment):

make deps
make deps-dev

Next, run it as follows from the root directory (it will run on port 8080):

export WEBHOOK_SECRET=yoursecrethere
export WEBHOOK_SEED=SXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

python -m examples.webhook.app

API Reference

The API reference can be found here.