Click to Pay Setup

Merchant setup

To process Click to Pay payments, register as a Digital Payments Application (DPA). Set up Click to Pay in the Connections dashboard which automatically registers and configures the DPA with Mastercard.

Prepare the server

Before loading Click to Pay with Secure Fields into the checkout, generate a checkout session via the API. This is made easy with the server-side SDKs.

Install a server-side SDK

Use the package manager in the preferred programming language to install the server-side SDK. Generating a checkout session can only be done server side and doing this client side is not recommended as it exposes the API key to customers.

dotnet add package Gr4vy

go get github.com/gr4vy/gr4vy-go

# Please check for the latest version
implementation 'com.gr4vy:sdk:1.0.0'

composer require "gr4vy/gr4vy-php"

pip install gr4vy

npm install @gr4vy/sdk
# or: yarn add @gr4vy/sdk

Please install the latest release of the preferred SDK.

Initialize the SDK client

Next, initialize the SDK with the ID of the instance and the private key.

using Gr4vy;
using Gr4vy.Models.Components;
using System.Collections.Generic;

// Loaded the key from a file, env variable, 
// or anywhere else
var privateKey = "..."; 

var sdk = new Gr4vySDK(
    id: "example",
    server: SDKConfig.Server.Sandbox,
    bearerAuthSource: Auth.WithToken(privateKey),
    merchantAccountId: "default"
);

package main

import (
	"context"
	gr4vy "github.com/gr4vy/gr4vy-go"
	"github.com/gr4vy/gr4vy-go/models/operations"
	"log"
	"os"
)

func main() {
	ctx := context.Background()

	privateKey := "...." // Private key loaded from disk or env var
	withToken := gr4vy.WithToken(privateKey, []JWTScope{ReadAll, WriteAll}, 60)

	s := gr4vy.New(
		gr4vy.WithID("example"),
		gr4vy.WithServer(gr4vy.ServerSandbox),
		gr4vy.WithSecuritySource(withToken),
		gr4vy.WithMerchantAccountID("default"),
	)
}

package hello.world;

import com.gr4vy.sdk.BearerSecuritySource;
import com.gr4vy.sdk.Gr4vy;
import com.gr4vy.sdk.Gr4vy.AvailableServers;
import com.gr4vy.sdk.models.components.AccountUpdaterJobCreate;
import com.gr4vy.sdk.models.errors.*;
import com.gr4vy.sdk.models.operations.ListTransactionsRequest;
import java.lang.Exception;
import java.util.List;

public class Application {

    public static void main(String[] args) throws Exception {

        String privateKey = "-----BEGIN PRIVATE KEY-----\n...."; // a valid private key

        Gr4vy sdk = Gr4vy.builder()
                .id("example")
                .server(AvailableServers.SANDBOX)
                .merchantAccountId("default")
                .securitySource(new BearerSecuritySource.Builder(privateKey).build())
            .build();
    }
}

declare(strict_types=1);

require 'vendor/autoload.php';

use Gr4vy;
use Gr4vy\Auth;

// Loaded the key from a file, env variable, 
// or anywhere else
$privateKey = "..."; 

$sdk = Gr4vy\SDK::builder()
    ->setId('example')
    ->setServer('sandbox')
    ->setSecuritySource(Auth::withToken($privateKey))
    ->setMerchantAccountId('default')
    ->build();

from gr4vy import Gr4vy, auth
import os

client = Gr4vy(
    id="example",
    server="production",
    merchant_account_id="default",
    bearer_auth=auth.with_token(open("./private_key.pem").read())
)

import fs from "fs";
import { Gr4vy, withToken } from "@gr4vy/sdk";

const gr4vy = new Gr4vy({
    server: "sandbox",
    id: "example",
    bearerAuth: withToken({
      privateKey: fs.readFileSync("private_key.pem", "utf8"),
    }),
});

This SDK needs to be initialized on your server-side. Please do not expose your private key to your client-side code.

This assumes the key you created in the previous step is kept in a secure location and can be loaded as a string. You could store this key in an environment variable or a secure vault.

To learn more about the API authentication, and how to generate a bearer token for use without the SDKs, please see the more extensive authentication guide.

Create a Checkout Session

With the SDK installed, use it to create a checkout session for use with Click to Pay.

const response = await client.newCheckoutSession();

response = client.create_new_checkout_session()

$checkout_session = $client->newCheckoutSession()

CheckoutSession session = client.newCheckoutSession()

curl -i -X POST "https://api.{instance_id}.gr4vy.app/checkout-sessions" \
    -H "Authorization: Bearer [JWT_TOKEN]" \
    -H "Content-Type: application/json"

Please refer to the API reference to learn more about our Checkout Sessions and the additional options that can be passed when creating them.

Create your checkout

With your checkout session ready, it’s time to start creating a card form that can support Click to Pay. The frontend integration is called Secure Fields and it essentially wraps each of your credit card input fields in a secure element, keeping you PCI-compliant and allowing for seamless integration with Click to Pay.

For more information on Secure Fields, please see the detailed guide which covers all the available options, events, and theming customizations available.

Install Secure Fields

There are three ways to install Secure Fields for use with Click to Pay: either as a React library, a Node library or straight off the CDN.

React
Node/CDN

npm install @gr4vy/secure-fields-react --save
# or: yarn add @gr4vy/secure-fields-react

Initializing Secure Fields

With Secure Fields installed it’s now possible to initialize the connection to your instance. It expects the checkout session ID you created earlier.

import { SecureFields } from "@gr4vy/secure-fields-react";

<SecureFields
  gr4vyId="example"
  environment="sandbox"
  sessionId="8e2adc90-681d-442b-acd4-2d5182e62c72"
  // enable debugging
  debug
>
  <Form />
</SecureFields>

When SecureFields is loaded without a valid sessionId it will error. We recommend only loading the component if the session ID is set.

{sessionId && (
  <SecureFields>
    ...
  </SecureFields>
)}

Create a card form

Next, add any of the 3 individual card fields to the form. Mix and match these with custom forms, and add custom labels.Let’s start by adding the form with 4 fields: the card holder’s name, the card number, card expiration date, and the security code for the card.

import { 
  CardForm, 
  CardNumber, 
  ExpiryDate, 
  SecurityCode,
  useSecureFields
} from '@gr4vy/secure-fields-react'

const secureFields = useSecureFields()

{/* This card form will automatically hide  */}
<CardForm
  onVisibilityChange={(visible: boolean) => {
    console.log('Card form visibility changed. Visible', visible)
  }}
>
  <div id="cc-form" className="max-w-xs">
    {/* You can add your own fields as well as secure fields */}
    <label for="cc-holder-name">Name</label>
    <input id="cc-holder-name" placeholder="Name on the card" />
    
    {/* These are fields that will become secure fields */}
    <label htmlFor="cc-number">Card number</label>
    <CardNumber styles={styles} />

    <label htmlFor="cc-expiry-date">Expiry date</label>
    <ExpiryDate styles={styles} />

    <label htmlFor="cc-security-code">Security code</label>
    <SecurityCode styles={styles} />

    <button onClick={() => secureFields.submit()}>Pay</button>
  </div>
</CardForm>

Each secure field should now be loaded on the page. Please see our more extensive guides on how to add event listeners and custom styles to Secure Fields.

Add Click to Pay

Next, add the Click to Pay components to show and hide their UI on demand.

import { 
  ClickToPay,
  ClickToPaySignIn
} from '@gr4vy/secure-fields-react'

 {/* The main Click to Pay component */}
<ClickToPay
  srcDpaId='{SRC_DPA_ID}'
  dpaName='{DPA_NAME}'
  dpaLocale='en_AU'
  cardBrands={['mastercard', 'visa', 'amex']}
  consentCheckbox='#click-to-pay-consent-checkbox'
  learnMoreLink="#click-to-pay-learn-more-link"
  // email='john@example.com' // optional: define a Click to Pay user e-mail instead of capturing it with the sign-in form
  /* mobileNumber={{
    countryCode: "61",
    phoneNumber: "491570159"
  }} */ // optional: define a Click to Pay user phone instead of capturing it with the sign-in form
/>

 {/* An optional sign-in with email or phone for Click to Pay would go here */}
<ClickToPaySignIn data-testid="sign-in">
  <label>Access your Click to Pay stored cards</label>
  <input type="text" className="email" ref={ref} />
  {/* This shows how to sign in with email. For the mobile number use the `mobileNumber` with a `countryCode` and `number` */}
  <button onClick={() => secureFields.clickToPay.signIn({ email: ref.current.value })}>
    Sign in
  </button>
</ClickToPaySignIn>

<CardForm>
  {/* ... */}

  <input type="checkbox" id="click-to-pay-consent-checkbox" />
  <label htmlFor="click-to-pay-consent-checkbox">
    Store my card with Click to Pay <a href="javascript:void(0)" id="click-to-pay-learn-more-link">Learn more</a>
  </label>

  {/* ... */}
</CardForm>

Secure Fields will automatically display and hide the Click to Pay Component, the sign in form, and your card form, based on the status of Click to Pay.

Handle form submission

Once the data has been submitted, use the onCardVaultSuccess property on the SecureFields component to create a transaction.

<SecureFields onCardVaultSuccess={async () => {
    // call your API
  }}
>...</SecureFields>

For more information on Secure Fields, please see our detailed guide which will cover all the available options, events, and theming customizations available.

npm install @gr4vy/secure-fields --save
# or: yarn add @gr4vy/secure-fields

<script src="https://cdn.{gr4vyId}.gr4vy.app/secure-fields/latest/secure-fields.js"></script>
<link
  rel="stylesheet"
  href="https://cdn.{gr4vyId}.gr4vy.app/secure-fields/latest/secure-fields.css"
/>

<!-- Please replace the `{gr4vyId}` with the name of your instance. -->

When using the CDN the latest version of the library is always pulled straight from the server for every request.

Initializing Secure Fields

With Secure Fields installed it’s now possible to initialize the connection to your instance. It expects the checkout session ID you created earlier.

import SecureFields from "@gr4vy/secure-fields";
// set up the environment
const gr4vyId = "example";
const environment = "sandbox";
const sessionId="8e2adc90-681d-442b-acd4-2d5182e62c72"
// initialize the SDK
const secureFields = new SecureFields({
  gr4vyId,
  environment,
  sessionId,
});
// enable debugging
secureFields.setDebug(true);

Create a card form

<form id="cc-form">
  <!-- You can add your own fields as well as secure fields -->
  <label for="cc-holder-name">Name</label>
  <input id="cc-holder-name" placeholder="Name on the card" />

  <!-- These are fields that will become secure fields -->
  <label for="cc-number">Card Number</label>
  <input id="cc-number" />

  <label for="cc-expiry-date">Expiry date</label>
  <input id="cc-expiry-date" />

  <label for="cc-security-code">Security Code</label>
  <input id="cc-security-code" />

  <input type="submit">Pay</button>
</form>

It is important to add all the card inputs including the number, expiration date, and security code. Without each of these fields, a transaction can not be processed. Additional inputs can be added to your form but they will not be handled by our library.Next, initialize each of the inputs as a secure field.

// Add fields using a querySelector compatible string
const number = secureFields.addCardNumberField("#cc-number", {
  placeholder: "Enter card number",
});

const securityCode = secureFields.addSecurityCodeField("#cc-security-code", {
  placeholder: "Enter CVV",
});

// Alternatively an HTML element can be passed directly
const expiryDate = secureFields.addExpiryDateField(
  document.querySelector("#cc-expiry-date"),
  {
    placeholder: "Enter expiry date",
  }
);

This example replaces each of the <input> fields for the card form with a new PCI secure field. It’s worth noting that we did not attach a secure field for the card holder name, instead, this field will remain a regular HTML input

Every field that Secure Field is attached to needs to be an HTML element. In this case, we attached the fields to <input> fields. The fields can be attached to any element using a querySelector-compatible query.

Each secure field should now be loaded on the page. Please see our more extensive guides on how to add event listeners and custom styles to Secure Fields.

Add Click to Pay

Next, add a placeholder component to your form so we know where to render the Click to Pay component. Additionally, add a checkbox to allow a customer not already enrolled to determine if they want to share the card data with Click to Pay or not. Finally, add the rest of the Click to Pay components to show and hide their UI on demand.

<div id="click-to-pay"></div>

<!-- Small form to let users sign in with Click to Pay, hidden by default -->
<div id="click-to-pay-sign-in" style="display: none;">
  <label>Access your Click to Pay stored cards</label>
  <input type="text" id="phoneOrEmail" />
  <button id="signInButton">Continue</button>
</div>

<form id="cc-form" style="display: none;">
  <!-- ...Secure fields inputs added previously -->

  <input type="checkbox" id="click-to-pay-consent-checkbox" />
  <label for="click-to-pay-consent-checkbox">
    Store my card with Click to Pay. <a href="javascript:void(0)" id="click-to-pay-learn-more-link">Learn more</a>
  </label>

  <input type="submit">Pay</button>
</form>

<script>
  var phoneOrEmail = document.querySelector('#phoneOrEmail')
  var signInButton = document.querySelector('#signInButton')
  signInButton.addEventListener('click', function () {
    clickToPay.signIn({ email: phoneOrEmail.value })
  })
</script>

Next, attach the secure field for Click to Pay to this element. This will require an HTML query for the consent checkbox that controls if the card data for a new card is shared with Click to Pay or not. Next to the consent label, add a link to let users learn more about Click to Pay. References to the card form and sign in HTML containers you added previously are also required.

const clickToPay = secureFields.addClickToPay('#click-to-pay', {
  srcDpaId: '{SRC_DPA_ID}',
  dpaName: '{DPA_NAME}',
  dpaLocale: 'en_AU',
  cardBrands: ['mastercard', 'visa', 'american-express'],
  consentCheckbox: "#click-to-pay-consent-checkbox",
  learnMoreLink: "#click-to-pay-learn-more-link",
  cardForm: "#cc-form",
  signIn: "#click-to-pay-sign-in"
  // email: 'john@example.com', // optional: define a Click to Pay user e-mail instead of capturing it with the sign-in form
  /* mobileNumber: {
    countryCode: "61",
    phoneNumber: "491570159"
  }, */ // optional: define a Click to Pay user phone instead of capturing it with the sign-in form
})

Secure Fields will automatically display and hide the Click to Pay Component, the sign in form, and your card form, based on the status of Click to Pay.

Handle form submission

To handle a form submission, listen to the submission of the <form> element or a click of the submit button. Then prevent the default behavior and submit Secure Fields. This will instruct the fields to post the card data (regular, or Click to Pay) to the API.

document.querySelector('#cc-form').addEventListener(
  "submit",
  (e) => {
    e.preventDefault()
    secureFields.submit()
  }
)

Once the data has been submitted, use the secureFields object to listen to the card data being successfully, or unsuccessfully vaulted.

secureFields.addEventListener(
  SecureFields.Events.CARD_VAULT_SUCCESS,
  () => {
    // Make an API call to your server to complete the transaction
  }
)

secureFields.addEventListener(
  SecureFields.Events.CARD_VAULT_FAILURE,
  () => {
    // Handle the inability to store the card data
  }
)

In the case of a single-page app, it might be useful to unload any of the event listeners when the form is unloaded.

Create a payment

With the card data stored in the vault, create a transaction on the server-side. To create a transaction, pass the amount, currency, as well as the payment method, in this case a checkout session.

var transaction = await client.Transactions.CreateAsync(
    transactionCreate: new TransactionCreate()
    {
        Amount = 1299,
        Currency = "USD",
        Country = "US",
        PaymentMethod =
            TransactionCreatePaymentMethod.CreateCheckoutSessionWithUrlPaymentMethodCreate(
                new CheckoutSessionWithUrlPaymentMethodCreate()
                {
                    Id = checkoutSession.Id,
                }
            ),
    }
);

amount := int64(1299)
currency := "USD"

checkoutSessionWithURLPaymentMethodCreate := components.CheckoutSessionWithURLPaymentMethodCreate{
    ID: checkoutSession.ID,
}
paymentMethod := components.CreateTransactionCreatePaymentMethodCheckoutSessionWithURLPaymentMethodCreate(checkoutSessionWithURLPaymentMethodCreate)

transactionCreate := components.TransactionCreate{
    Amount:        amount,
    Currency:      currency,
    PaymentMethod: &paymentMethod,
}

transaction, err := client.Transactions.Create(ctx, transactionCreate, nil, nil)

// handle response

CreateTransactionResponse transactionResponse = gr4vyClient.transactions().create()
    .transactionCreate(TransactionCreate.builder()
        .amount(1299L)
        .currency("USD")
        .paymentMethod(TransactionCreatePaymentMethod.of(CheckoutSessionWithUrlPaymentMethodCreate.builder()
            .id(checkoutSession.id())
            .build()))
        .build())
    .call();

Transaction transaction = transactionResponse.transaction().orElse(null);

// handle response

$transactionCreate = new TransactionCreate(amount: 1299, currency: 'USD', paymentMethod: new CheckoutSessionWithUrlPaymentMethodCreate(id: $checkoutSession->id));
$response = self::$sdk->transactions->create($transactionCreate);
$transaction = $response->transaction;

transaction: models.Transaction = client.transactions.create(
    amount=1299,
    currency="USD",
    payment_method={
        "method": "checkout-session",
        "id": checkout_session.id,
    }
)

const transaction = await gr4vy.transactions.create({
    amount: 1299,
    currency: "USD",
    paymentMethod: {
    method: "checkout-session",
    id: checkoutSession.id
    }
})

The returned transaction includes details about the payment method used, and the status of the transaction.

{
  "type": "transaction",
  "id": "fe26475d-ec3e-4884-9553-f7356683f7f9",
  "status": "authentication_succeeded",
  "amount": 1299,
  "currency": "AUD",
  "payment_method": {
    "type": "payment-method",
    "id": "77a76f7e-d2de-4bbc-ada9-d6a0015e6bd5",
    "method": "card",
    "scheme": "visa",
    "expiration_date": "07/24",
    ...
  },
  ...
}

Client-side vs server-side

A transaction should be created server-side instead of client-side, as there are many reasons why a success message may never reach your server, leaving you in a state where it’s unclear if your transaction has succeeded.

Error handling

The available error codes for Click to Pay are as follows. It is recommended to catch and handle Click to Pay errors as required.

CODE_INVALID - The user entered an incorrect OTP. An error message is also displayed on the OTP component.
INVALID_CARD - The user entered incorrect card details, or the details of a card that is not one of the supported schemes.
ACCT_INACCESSIBLE - The user’s account is temporarily not accessible.
USER_NOT_RECOGNIZED - The user is not recognized by Click to Pay (typically when a user hasn’t signed in yet).
UNKNOWN - An unknown error occurred. These are usually unrecoverable. For example, the Click to Pay library was not initialized due to an invalid parameter.
RETRIES_EXCEEDED - The user has exceeded the maximum number of retries filling in their one-time password (OTP) and their profile is locked. An error message is also displayed in the OTP component. It is recommended to hide the Click to Pay component for the user at this point.
SIGN_OUT_FAILED - When attempting to sign out via the “Not you?” link, it is possible that Click to Pay is not able to sign out the user. It is recommended to hide the Click to Pay component for the user at this point.

React
Node/CDN

<SecureFields
  ...
  onClickToPayError={({ error }) => {
    if (error.code === 'RETRIES_EXCEEDED' ||
        error.code === 'SIGN_OUT_FAILED') {
      // Hide the Click to Pay component
      setClickToPayVisible(false);
    }
    console.error(error);
  }}
/>

secureFields.addEventListener(
  SecureFields.Events.CLICK_TO_PAY_ERROR,
  ({ error }) => {
    console.error(error);

    if ((error.code === 'RETRIES_EXCEEDED' || 
          error.code === 'SIGN_OUT_FAILED') &&
          clickToPay) {
      // Hide the Click to Pay form
      clickToPay.hide();
    }
  }
)

Events

React
Node/CDN

The following props can be used on the SecureFields component to listen to specific Click to Pay events.

Name	Event	Description
`onMethodChange`	`METHOD_CHANGE`	Triggered when a user switches between the card and the Click to Pay payment methods.
`onClickToPayInitialized`	`CLICK_TO_PAY_INITIALIZED`	Triggered when Click to Pay is loaded and its `init` method called successfully.
`onClickToPayReady`	`CLICK_TO_PAY_READY`	Triggered when a Click to Pay user is identified correctly and can start using Click to Pay.
`onClickToPaySignOut`	`CLICK_TO_PAY_SIGN_OUT`	Triggered when a Click to Pay user signs out using the “Not me” / “Not my cards” functionality.
`onClickToPayError`	`CLICK_TO_PAY_ERROR`	See Error Handling
`onClickToPayCancel`	`CLICK_TO_PAY_CANCEL`	Triggered when a Click to Pay user cancels the checkout process from within the UI.
`onClickToPayCheckoutWithNewCard`	`CLICK_TO_PAY_CHECKOUT_WITH_NEW_CARD`	Triggered when a Click to Pay user starts the process of checking out with a new (not enrolled) card.
`onClickToPayUnableToLoadDpa`	`CLICK_TO_PAY_UNABLE_TO_LOAD_DPA`	Triggered when the provided Click to Pay DPA cannot be loaded.

Additionally, you can add the prop onVisibilityChange to the ClickToPay, ClickToPaySignIn and CardForm components to listen to visibility change events (CLICK_TO_PAY_VISIBILITY_CHANGE, CLICK_TO_PAY_CARD_FORM_VISIBILITY_CHANGE, CLICK_TO_PAY_SIGN_IN_VISIBILITY_CHANGE).

<CardForm onVisibilityChange={(visible) => console.log('Card form visible', visible)} />

The following Click to Pay events can be listened to by attaching an event handler to the SecureFields instance using the addEventListener method.

Name	Description
`METHOD_CHANGE`	Triggered when a user switches between the card and the Click to Pay payment methods.
`CLICK_TO_PAY_INITIALIZED`	Triggered when Click to Pay is loaded and its `init` method called successfully.
`CLICK_TO_PAY_READY`	Triggered when a Click to Pay user is identified correctly and can start using Click to Pay.
`CLICK_TO_PAY_SIGN_OUT`	Triggered when a Click to Pay user signs out using the “Not me” / “Not my cards” functionality.
`CLICK_TO_PAY_ERROR`	See Error Handling
`CLICK_TO_PAY_CANCEL`	Triggered when a Click to Pay user cancels the checkout process from within the UI.
`CLICK_TO_PAY_CHECKOUT_WITH_NEW_CARD`	Triggered when a Click to Pay user starts the process of checking out with a new (not enrolled) card.
`CLICK_TO_PAY_UNABLE_TO_LOAD_DPA`	Triggered when the provided Click to Pay DPA cannot be loaded.
`CLICK_TO_PAY_VISIBILITY_CHANGE`	Triggered when the Click to Pay element is shown or hidden.
`CLICK_TO_PAY_CARD_FORM_VISIBILITY_CHANGE`	Triggered when the card form container is shown or hidden.
`CLICK_TO_PAY_SIGN_IN_VISIBILITY_CHANGE`	Triggered when the sign in container is shown or hidden.

// Listen for the different Click to Pay events
secureFields.addEventListener(
  SecureFields.Events.METHOD_CHANGE, () => {
    console.log('Method changed');
  }
)

Testing

To test Click to Pay in the sandbox environment, use the test resources below. These sandbox environments and test cards are provided and maintained by the card networks.

Click to Pay test cards — test card numbers for Click to Pay scenarios.
Mastercard sandbox account — manage your Mastercard Click to Pay sandbox account and enrolled cards.
Visa sandbox account — manage your Visa Click to Pay account and enrolled cards.

Links

Quick start: Secure fields

Guide: Vault Forward

API Reference: New checkout session

API Reference: New transaction

Get started

Integration guides

Best Practices

Resources

Features

Other

Click to Pay Setup

Merchant setup

Prepare the server

Install a server-side SDK

Initialize the SDK client

Create a Checkout Session

Create your checkout

Install Secure Fields

Initializing Secure Fields

Create a card form

Add Click to Pay

Handle form submission

Initializing Secure Fields

Create a card form

Add Click to Pay

Handle form submission

Create a payment

Client-side vs server-side

Error handling

Events

Testing

Links

​Merchant setup

​Prepare the server

​Install a server-side SDK

​Initialize the SDK client

​Create a Checkout Session

​Create your checkout

​Install Secure Fields

​Initializing Secure Fields

​Create a card form

​Add Click to Pay

​Handle form submission

​Initializing Secure Fields

​Create a card form

​Add Click to Pay

​Handle form submission

​Create a payment

​Client-side vs server-side

​Error handling

​Events

​Testing

​Links

Merchant setup

Prepare the server

Install a server-side SDK

Initialize the SDK client

Create a Checkout Session

Create your checkout

Install Secure Fields

Initializing Secure Fields

Create a card form

Add Click to Pay

Handle form submission

Initializing Secure Fields

Create a card form

Add Click to Pay

Handle form submission

Create a payment

Client-side vs server-side

Error handling

Events

Testing

Links