Category: Blockchain

Compiling, deploying and calling Ethereum smartcontract using Python

Posted on by yohanes.gultom@gmail.com

We use Python 3.5.3 on Ubuntu 16.04 with setup below: pip3 install web3==4.7.2 py-solc==3.2.0 python3 -m solc.install v0.4.24 export PATH=”$PATH:$HOME/.py-solc/solc-v0.4.24/bin” The core packages are: web3 : official python interface to interact with Ethereum blockchain py-solc: official python wrapper for solc (solidity compiler). Hence solc needs to be installed (covered in setup above) To compile a solidity… Read More

Sign Ripple transaction locally using ripple-lib-java

Posted on by yohanes.gultom@gmail.com

Since rippled 1.1.0 disables public signing by default, we either need to host our own API server or sign Ripple transaction locally. Fortunately, ripple-lib-java gives clue on how to do this in one of its example. Long story short, we can use this simple method to do the signing: import java.math.BigDecimal; import com.ripple.core.types.known.tx.txns.Payment; import com.ripple.core.types.known.tx.signed.SignedTransaction;… Read More

Check balance and send Ripple (XRP) using Java

Posted on by yohanes.gultom@gmail.com

Update: As mentioned in here, since rippled 1.1.0 remote sign API is not allowed by default anymore. If you try to call it on wss://s.altnet.rippletest.net:51233 you will get “Signing is not supported by this server” error. Check this post on how to sign transaction locally using Java Ripple (XRP) provides some options to interact with their… Read More

Node.js – smart contract integration with truffle-contract and infura.io

Posted on by yohanes.gultom@gmail.com

While running your own Ethereum node with geth by using web3js from node.js (backend) app is a common solution, connecting to a public Ethereum node such as infura.io and using [truffle-contract](https://github.com/trufflesuite/truffle-contract] gives some benefits: No need to maintain your own Ethereum node (syncing a full node requires huge storage space! (around 40 GB for Ropsten))… Read More

Sending Bitcoin programmatically using BlockCypher API

Posted on by yohanes.gultom@gmail.com

BlockCypher provides convenient REST APIs to send cryptocurrency like Bitcoin easily. Here are two APIs that we can use to send Bitcoin from one address to another: 1. Build transaction skeleton https://api.blockcypher.com/v1/btc/test3/txs/new 2. Push signed transaction https://api.blockcypher.com/v1/btc/test3/txs/send Here are the step by steps of using those APIs in JavaScript (Node.js) in testnet3 Bitcoin network. First,… Read More