Permissionless Blockchain Programming
Fri Jul 27, 2018 · 910 words

Leverage the blockchain so your app needs neither permission nor forgiveness. This is my quick adventure into using NodeJS and the Ethereum blockchain to write an unstoppable app.

TLDR; I built an app that takes the Gitcoin Bounties and creates an RSS Feed using NodeJS, Web3JS, AWS S3, and AWS Lambda

Anyone who has deployed an app to the Google Play Store or the Apple App Store or built something using the Twitter API or anything that requires permission to do can tell you that the rug can be pulled out from under you at any moment. You can wake up to an email about your app “violating” some obscure Terms of Service clause or hit some limit or maybe things just stop working and you have to just figure it out.

One of the interesting things about programming with a distributed ledger system, the Ethereum blockchain in this case, is that if you can talk the protocol then you can use the ecosystem. That’s it. No Terms of Service need to be accepted, no API keys to revoke, you need only the documentation to get started. In the case of Ethereum, you need only work within the confines of the public smart contract interface. If the code works, it will work forever. It’s a nice feeling.

The project is pretty straightforward: Take the Gitcoin bounties and turn them into an RSS feed.

If you are not familiar with Gitcoin, they are a community where you can get paid in cryptocurrencies to complete work on open-source repositories, among other great things. Check them out, the community is excellent. Gitcoin does not currently have an RSS feed and I really enjoy both the Gitcoin community and consuming things via RSS so it seemed like a useful goal to help at least 1 person (me).

How the data is structured:

A solution would include:

Other considerations:

My approach:

A quick diagram will help us:

Gitcoin RSS Sequence Diagram

The more interesting part of the app is how to interact with a smart contract using Web3JS, let’s have a look:

// load the contract data so we can use its methods
const abiArray = require('../contract-abi.json');

const Web3 = require('web3');

const contract = (nconf) => {
    const ethNodeAddress = nconf.get('eth_address');

    // set the connection info
    const web3 = new Web3(
        new Web3.providers.HttpProvider(ethNodeAddress));
    // load the contract and make an object out of its
    // interface
    const BountyContract = web3.eth.contract(abiArray);
    // link the contract to a current deployment
    const contractInstance =

    // call a method on the contract with no args
    const getNumBounties = (cb) => {

    // return a promise for a contract method that
    // takes an arg and has returned data
    const getBountyData = (bountyId) => {
        return new Promise((resolve, reject) => {
             (error, bountyData) => {
                if (error) {
                } else {
                    resolve([bountyId, bountyData]);

    return {
        getBountyData: getBountyData,
        getNumBounties: getNumBounties


Pretty straightforward. You can get the ABI ( Application Binary Interface ) for lots of contracts via, ours is at The JSON in contract-abi.json is simply copy pasted from there. The ABI is an interface description of how to interact with the contract.

That’s about it. You can get the feed at: and find the full project at Which has the full implementation.


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