In dfuse, how do I use `get_action_traces` to get notifications when certain transaction is created and when it's irreversible?

Question

Could someone point me to how to use get_action_traces to get notification when certain transaction is created and when it's irreversible?

How should I structure the code?

Answer 1

There is currently no direct way to get notified when a certain transaction is created. You will need to use both get_action_traces and get_transaction_lifecycle to achieve what you want.

The overall idea is the following:

• Listen for specific actions via get_action_traces
• For each matching action, extract transaction ID from the ActionTrace response.
• Listen on get_transaction_lifecycle
• Wait for a TransactionLifecycle for which the execution_irreversible is true (meaning the transaction is now irreversible).

Here a quick example using eosws-js that does that:

import { socketFactory, runMain, waitFor } from "./config"
import {
  EoswsClient,
  InboundMessage,
  InboundMessageType,
  createEoswsSocket,
  ActionTraceData,
  ErrorData,
  TransactionData
} from "@dfuse/eosws-js"

const CONTRACTS = ["eosmechanics", "eosknightsio", "eosiotokener"]

const client = new EoswsClient(createEoswsSocket(socketFactory))

let actionStream: any
let transactionStream: any
let terminate = false
let transactionListening = false

const onMessage = (message: InboundMessage<any>) => {
  switch (message.type) {
    case InboundMessageType.ERROR:
      const error = message.data as ErrorData
      console.log(`Received error: ${error.message} (${error.code})`, error.details)
      break

    case InboundMessageType.ACTION_TRACE:
      onActionMessage(message)
      break

    case InboundMessageType.TRANSACTION_LIFECYCLE:
      onTransactionMessage(message)
      break
  }
}

const onActionMessage = (message: InboundMessage<any>) => {
  const data = message.data as ActionTraceData<any>
  const action = data.trace.act

  if (!transactionListening) {
    transactionListening = true

    console.log(`Action "${action.name}" received for account "${action.account}".`)
    console.log(`About to listening for transaction "${data.trx_id}" to become irreversible`)

    actionStream.unlisten()

    transactionStream = client.getTransactionLifecycle(data.trx_id, { req_id: "transaction" })
    transactionStream.onMessage(onMessage)
  }
}

const onTransactionMessage = (message: InboundMessage<any>) => {
  const data = message.data as TransactionData
  const lifecycle = data.lifecycle

  if (lifecycle.execution_irreversible === true && terminate !== true) {
    console.log("Transaction passed irreveribility.")
    terminate = true
    transactionStream.unlisten()
  } else {
    console.log("Transaction progressing through irreveribility ...")
  }
}

async function main() {
  await client.connect()

  actionStream = client.getActionTraces({
    accounts: CONTRACTS.join("|"),
    action_names: "transfer|issue"
  })

  console.log("Waiting for filtered action to appear...")
  actionStream.onMessage(onMessage)

  while (!terminate) {
    await waitFor(2500)
  }
}

runMain(main)