Creating offline transactions on the Ethereum blockchain using Java and Pushtx API
The Ethereum blockchain is a decentralized, public and safe platform for storing and transmitting transactions. One of its key features is the ability to create and transmit offline transactions through Pushtx API from external applications, such as mobile applications or web customers. In this article, we will explore how to create an offline transaction in Java that can be broadcast on the Ethereum blockchain using Pushtx API.
Background
Pushtx API allows developers to send gross transactions to a node in the Ethereum network, without waiting for the transaction to be checked by a colleague (ie another knot). This makes it possible to create and disseminate offline transactions from external applications. To use Pushtx API, you need to get an Ethereum’s ETHREUM wallet address that is not already used as a wallet.
Choosing between bitcoinj and pushtx
There are two popular libraries for the interaction with the Ethereum blockchain in Java: Bitcoinj and Pushtx. Here is a short comparison:
* Bitcoinj : A client library with complete features that allows you to interact with Ethereum blockchain using various protocols (for example, JSON-RPC, HTTP). However, it requires a wallet address and is not specially designed for offline transactions.
* Pushtx : A library developed by Infura, a cloud -based infrastructure provider for the interaction with the Ethereum network. Pushtx offers a simple API for creating and sending gross transactions to the nodes in the Ethereum network.
For this example, we will use pushtx.
Creating an offline transaction in Java
To create an offline transaction using Pushtx, you must:
Pushtx class:Java
IMPORT COM.INFURA.PUSHTX.PUSHTX;
IMPORT COM.INFURA.PUSHTX.PUSHTRANSACTION;
Public Class offlinetransactionexample {
Public Static Void Main (String [] Args) {
// set -va URL of the Ethereum node (for example, "
String nodeurl = "
// Create a new instance of Pushtx class
Pushtx Pushtx = New Pushtx (Nodeurl);
}
}
`Java
// Set the Ethereum wallet address
String Walletaddress = "0xyour_wallet_address";
Java
// create a new pushtransction object
Pushtransction transaction = pushtx.createtransction (
NEW STRING [] {"0x1234567890ABCDEF", "your transaction data"})
);
signing offline transaction
To sign the offline transaction, you must use the "Signmessage" methodPushtx ‘:
`Java
// sign the transaction using your private key
String signtransction = pushtx.signtransction (transaction, string new [] {"you_private_key"});
Offline transaction broadcast
Once you have created and signed the offline transaction, you can transmit it to the Ethereum network using Pushtx API. Here's an example of how to do this:
Java
// Create a new instance of Pushtx class with the same URL and Node wallet
Pushtx Pushtx = New Pushtx (Nodeurl);
// set the transaction signed as a useful task for broadcasting
String utload = signedransction;
// broadcasts transaction using Pushtx API
Pushtx.Broadcast (useful task, new string [] {"0x1234567890ABCDEF", "Your transaction data"});
Code samples
Here is an example of a code sample that demonstrates how to use the above steps:
` Java
IMPORT COM.INFURA.PUSHTX.PUSHTX;
IMPORT COM.INFURA.PUSHTX.PUSHTRANSACTION;
Public Class offlinetransactionexample {
Public Static Void Main (String [] Args) {
// set -va URL of the Ethereum node (eg.
