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2.0.0 • Public • Published

Backend SDK


This module is used to send notifications to EPNS channels easy. It Provides an abstraction layer above advanced internal EPNS notification functions.

It is written in typescript and requires node v10.0.0 or higher. Most features will work with nodejs v6.0.0 and higher but using older versions than v10.0.0 is not recommended.



npm install @epnsproject/backend-sdk


In order to use this package, you must first have created a channel at EPNS. Then note the private key of the account you used to create the channel, because we would be using it in this tutorial

// Import the required packages
EpnsSDK, { InfuraSettings, NetWorkSettings, EPNSSettings } = require("'@epnsproject/backend-sdk");
const ethers = require('ethers');

// Define the parameters we would need in order to initialize the SDK
const  CHANNEL_PK = '0x0000000000000000000000000000000000000000000000000000000000000fff'; // the private key of the channel

// Initialise the SDK
const  epnsSdk = new EpnsSDK(CHANNEL_PK);

// get the subscribers to your channel
const allSubscribers = await epnsSdk.getSubscribers()

// send a notification to your subscribers
const response = await epnsSdk.sendNotification(
      recipients, //the recipients of the notification
      pushNotificationTitle, // push notification title
      pushNotificationBody, //push notification body
      notificationTitle, //the title of the notification
      notificationBody, //the body of the notification
      notificationType, //1 - for broadcast, 3 - for direct message, 4 - for subset.
      link, //the CTA of the notification, the link which should be redirected to when they click on the notification


Initialising the SDK

new EpnsSDK(
	channelKey: string,
		communicatorContractAddress = config.communicatorContractAddress,
		communicatorContractABI = config.communicatorContractABI,
		channelAddress = null,
    networkToMonitor =  this.cSettings.networkToMonitor

	} = {}
Parameter Description Default Value
channelKey The private key of the account used to create a channel on EPNS N/A (This is the only parameter that is required)
communicatorContractAddress an override parameter if you intend to use a different communicator contract from the production one For Main Network:0xb3971BCef2D791bc4027BbfedFb47319A4AAaaAa and for Polygon Network: 0xb3971BCef2D791bc4027BbfedFb47319A4AAaaAa
communicatorContractABI The ABI of the communicator contract specified Defaults to the latest communicator contract published by EPNS
channelAddress The ethereum address used to create the channel defaults to ethers.utils.computeAddress(channelKey) which is the public key of the specified private key
networkKeys These are important if you want to perform any on chain activities, you will have to provide infura keys The type of the object containing the keys are as follows interface NetWorkSettings {alchemy?: string;infura?: {projectID: string;projectSecret:string;};etherscan?: string;}
notificationChainId The chain on which you want to send notifications defaults to 1 which is for the main network, other option is 137 which is for the polygon network
networkToMonitor The SDK has a method to get a contract, this parameter specifies the chain to fetch contracts for when initialising a contract using the SDK, it defaults to 1 which is for the main network, but it could potentially be any evm compatible chain.

Getting the subscribers of a particular channel

const  subscribers = await  epnsSdk.getSubscribedUsers();

This returns an array of addresses, which would be those already subscribed to your channel

Sending notifications using the SDK

* Send Notification
* @description Sends notification to a particular user
* @param user User Address
* @param title push notification title of Notification
* @param message push notification Message of Notification
* @param payloadTitle Full notification Title
* @param payloadMsg Full notification Content
public  async  sendNotification(
    recipient: string,
    pushNotificationTitle: string,
    pushNotificationMessage: string,
    notificationTitle: string,
    notificationMesssage: string,
    notificationType: number,
    cta: string | undefined,
    img: string | undefined,
    simulate: any,
  { offChain = true } = {}, //add optional parameter for offchain sending of notification
) {}
Parameter Description Value
recipient The recipient of the notification it would be equal to the channelAddress for a broadcast notification(type=1), it would be equal to the recipient address for a direct(targetted notification)(type=3), it would be equal to the comma seperated string of addresses for subset notifications(type=4) e.g0xaddress1, 0xaddress2, 0xaddress3
pushNotificationtitle This is the title of the notification which would be displayed on the push notification shorter form of the notification title, it could also be the same as the actual notification title
pushNotificationMessage This is the message which is going to be displayed on the push notification for this notification usually a shorter version of the message, but could also be the actual message
notificationTitle The title/heading of the notification about to be sent any string which is the title of your notification
notificationMesssage The content of the notification to be sent could be any string which contains some text
notificationType The type of notification being sent 1 ->Broadcast notification to every member of the channel. 3 -> Direct/targetted notification to a particular member of the channel 4 -> subset notifications to a group of subscribers of the channel
cta The url which you want user's to be redirected to upon clicking of the notifications URL or Undefined
img A url which links to an image you want to be displayed along with your notification
simulate An object which contains information used for testing purposes or simulating notification can safely be set to null
{ offChain = true } an optional parameter which is used to specify choosing to use off chain notifications defaults to use off chain notifications.

Getting a deployed contract from the sdk

async  getContract(
	address: string,
	abi: string
) {}
Parameter Description Default Value
address Specify the address of which the contract you seek exists N/A - required parameter
abi Specify the abi of which the contract you seek N/A - required parameter


MAINNET 1 EPNS CORE CONTRACT 0x66329Fdd4042928BfCAB60b179e1538D56eeeeeE
POLYGON 137 EPNS COMMUNICATOR CONTRACT 0xb3971BCef2D791bc4027BbfedFb47319A4AAaaAa




npm i @epnsproject/backend-sdk

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