Ethereum: How to Use WalletNotify
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WalletNotify is a mechanism to receive notifications from your Ethereum wallet when certain events occur, such as balance updates, transaction approvals, or even the creation of new Ethereum nodes. This is an optional feature that allows you to be notified of wallet activities in real time.
Using WalletNotify with JSON-RPC
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To use WalletNotify with a JSON-RPC call, you need to create a file called walletnotify.json
in the root directory of your Ethereum node configuration. This file specifies the notification handlers that your wallet uses. should follow them.
Here is an example of what this file might look like:
{
"notifier": {
"transactions": [
{
"event": "transaction.created",
"handler": "handle_transaction_created"
},
{
"event": "balance.increase",
"handler": "handle_balance_increase"
}
]
},
"handler": {
"type": "json-rpc",
"method": "eth_getTransactionCount",
"parameters": [],
"callOptions": {},
"value": {}
}
}
In this example, we specify two notification handlers: handle_transaction_created
and handle_balance_increase
. The “transaction.created” event is triggered when a new Ethereum transaction is created, while the “balance.crease” event is triggered when the wallet balance increases.
Writing to “walletnotify.json”
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To use WalletNotify with the wallet daemon, you need to write a script (called “transaction.sh”) that generates an HTTP request for each notification. This script should call the JSON-RPC method specified in the walletnotify.json
file.
Here is an example of what this script might look like:
#!/bin/bash

Get the current transaction countTX_COUNT=$(eth_getTransactionCount)
Create a notification messageprintf "Transaction created: %s\n" $(echo "$TX_COUNT")
Call the JSON-RPC method to get the new transaction counteth_getTransactionCount --gaslimit=2000000 --value=0 100
This script generates an HTTP request with the following headers:
Content-Type
: application/json
X-ChainId
: Ethereum chain ID (usually “0”)
X-Priority
: Priority level of the notification (usually “5”)
The response from the wallet daemon should be a JSON object containing the updated transaction count. You can then parse this response and use it as needed.
Example Use Case
—————
Let’s say you want to receive notifications when your balance is low. Ethereum is growing or when new transactions are created on the testnet. You will create a file “walletnotify.json” with the following content:
{
"notifier": {
"transactions": [
{
"event": "balance.increase",
"handler": "handle_balance_increase"
},
{
"event": "transaction.created",
"handler": "handle_transaction_created"
}
]
},
"handler": {
"type": "json-rpc",
"method": "eth_getTransactionCount",
"parameters": [],
"callOptions": {},
"value": {}
}
}
Next, you will run the transaction.sh
script to generate HTTP requests for each notification. You can use a tool like curl
or a web browser’s developer tools to inspect these requests and see how they are used.
Conclusion
———-
WalletNotify is an optional feature that allows you to be notified of your Ethereum wallet’s activities in real time. By specifying notification operators in `walletnotify.