DID Tasks

Motivation

Stretch goal: develop a very quick POC that shows how a user might go through the flow of 1) creating the suggested-required off-chain data, 2) grab the URI of that off-chain data and post it on-chain, and 3) have a singular DB that indexes and aggregates the important information from both the on-chain and off-chain data.

Stretch goal 2: Index information from another, centralized DB into the singular DB, and provide an endpoint that allows users to run very basic queries on the aggregated data set.

Summary

This POC mais goal is to allow an user to create a DID (Decentralized Identifier) to save off-chain data and to refer it on-chain

How it works

Technologies

• Ceramic Newtork and ComposeDB as the off-chain decentralized database
• Ethereum Sepolia as the on-chain storage
• Web3 app based on React, Hardhat and Infura
• Metamask wallet
• The Graph
• Solidity smart contract

Requirements

Install dependencies and run Wheel as described in here. After running the wheel you have the CLI for ceramic and composeDB, and a new /ceramic-app created:

• Node.js v16 (tip: use nvm to choose version 16)
• jq
• ./wheel

Use CLI to generate a random private key and the associated DID (e.g. did:key:z6M...icbamu)

$ composedb did:generate-private-key
$ composedb did:from-private-key <private-key>

Add the DID to the /ceramic-app/daemon_config.json file under the admin-dids list.

Creating a custom composite

ComposeDB has some pre-defined models that you can use:

$ composedb model:list –table # list models
$ composedb composite:from-model <model> # using a pre-defined model

For this app we will create a simple composite in graphql. Run the following commands to create, deploy and compile the composite:

$ composedb composite:create tasks.graphql --output=tasks-composite.json --did-private-key=<private-key>
$ composedb composite:deploy tasks-composite.json --ceramic-url=http://localhost:7007 --did-private-key=<private-key>
$ composedb composite:compile tasks-composite.json runtime-tasks-composite.json

The tasks.graphql file:

type Tasks @createModel(accountRelation: LIST, description: "A simple list of Tasks")
@createIndex(fields: [{path: "title"}])
@createIndex(fields: [{path: "description"}])
@createIndex(fields: [{path: "status"}])
{
  title: String! @string(minLength: 1, maxLength: 100)
  description: String @string(minLength: 1, maxLength: 100)
  status: TaskStatus! @string(minLength: 1, maxLength: 100)
  hours: Int
}

enum TaskStatus {
  NOT_STARTED
  STARTED
  FINISHED
  BLOCKED
  CANCELED
}

Also generate a definition for the app:

$ composedb composite:compile tasks-composite.json definition.js --ceramic-url=http://localhost:7007 

Setup the environment

Start a local Ceramic node connected to the Clay Testnet at https://localhost:7007

$ ceramic daemon --config daemon_config.json

Start a ComposeDB Yoda GraphiQL server at https://localhost:5005 using the private-key created and the runtime-tasks-composite.json composite

$ composedb graphql:server --ceramic-url=http://localhost:7007 --graphiql runtime-tasks-composite.json --did-private-key=<private-key> --port=5005

Configuring for Sepolia testnet

1. Change Metamask network to Sepolia testnet
2. Give you some credits using a Sepolia faucet
3. Create an account on Infura or Alchemy

Create an account and a project on Infura, take note of project ID

Project: My POC
ID: 1f9**********20d

Add Sepolia network to file hardhat.config.js

sepolia: {
      url: "https://sepolia.infura.io/v3/4b4d5e12505f4248ab2ba918fdcec22c",
      accounts: [`0x${process.env.PRIVATEKEY}`]
    }

Compile solidity source code

$ npx hardhat compile

Export the Metamask private-key and set as an environment variable, so that Hardhat can deploy the contract on the accounter's behalf

$ export PRIVATEKEY="<private key of sepolia account on Metamask>"

Deploy the contract to Sepolia testnet:

$ npx hardhat run scripts/deploy.js --network sepolia
> Contract deployed to: 0xB8d**********************88C1

Update the contract address to the /src/App.js file.

Check the contract at Etherscan for Sepolia Testnet

Usage

$ npm start

Event listener

$ ts-node events.ts

REST HTTP API

$ ts-node api.ts