Updated on February 19, 2021

How to listen for transactions receipts

Use the Orchestrate SDK to listen for successful transactions (mined) on any Blockchain network. The process of sending transactions on Ethereum is asynchronous, meaning that Orchestrate notifies Kafka once the transaction receipt is ready.

Orchestrate allows you to:

• Listen and decode the events of transactions from smart contracts registered in Orchestrate.
• Listen to all external transactions of the network.

Get a transaction receipt

Prerequisites

• A registered chain
• A running listener (see example below)
• A successfully sent transaction

Steps

1. Instantiate a consumer connected to Kafka: const consumer = new Consumer(['localhost:9092']).
2. Execute the connect() function of the consumer.
3. Register an event listener on the consumer (see example below).
4. Execute the consume() function on the consumer.

Important

For each successfully received transaction receipt, we recommend executing the commit() function to notify Kafka the message has been successfully processed and that it should not be read again even if the listener restarts.

Example

JavaScript (SDK)

await consumer.connect()

  // Register the event listener before calling consume
  consumer.on(EventType.Response, async (message: ResponseMessage) => {
    const { offset, topic, value } = message.content()

    console.log('Message received !', {
      Id: value.id,
      jobUUID: value.jobUUID,
      offset,
      topic,
      chain: value.chain
    })

    if (value.errors && value.errors.length !== 0) {
      console.log('Transaction failed!', { errors: value.errors, txContext: value.txContext })
    } else {
      console.log('Receipt:', value.receipt)
    }

    // We commit every message
    await message.commit()
  })

  await consumer.consume()

Output on successful transaction

Message received ! {
  Id: '34e7fb86-a971-462b-bd96-ad973eb31e6e',
  jobUUID: '83e8defa-2c0c-4a03-b56d-a6949a1c98b0',
  offset: '0',
  topic: 'topic-tx-decoded',
  chain: 'besu'
}
Receipt: {
  blockHash: '0x42ba84709344d4456c77f138b26be875ce6b9197f2864956c0edc2b75208e4c1',
  blockNumber: 21,
  txIndex: 0,
  txHash: '0xd1e8a764c563d315267389aa5e08de797a8879038f555b484f86fa490c5717ee',
  status: true,
  contractAddress: '0x2F4aeA4fcff7b774fccd649818285C69a9e87A76',
  gasUsed: 1017305,
  cumulativeGasUsed: 1017305,
  postState: undefined,
  bloom: '0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000008000000008000000000000000000000000000020000000000020000000000000000000800000000000000000000000010000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000080000000000000000000000000000000000000002000000000000000000000000000000000000000000000040000020000400000000000000000000000000000000000000000400000000000000000000',
  logs: [
    {
      address: '0x2F4aeA4fcff7b774fccd649818285C69a9e87A76',
      topics: [Array],
      data: '0x00000000000000000000000000000000000000000000021e19e0c9bab2400000',
      event: 'Transfer(address,address,uint256)',
      decodedData: [Object],
      blockNumber: 21,
      txHash: '0xd1e8a764c563d315267389aa5e08de797a8879038f555b484f86fa490c5717ee',
      txIndex: 0,
      blockHash: '0x42ba84709344d4456c77f138b26be875ce6b9197f2864956c0edc2b75208e4c1',
      index: 0,
      removed: false
    }
  ],
  revertReason: undefined,
  output: undefined,
  privateFrom: undefined,
  privateFor: [],
  privacyGroupId: undefined
}

Decode the revert reason

Revert reason, if handled by the smart contract, is an information returned by nodes in case of error in the smart contracts execution. Smart contracts have to use the revert or require features to be able to return a revert reason.

The ERC20 token smart contract for instance can return a revert reason when not enough tokens are available at the source address when transferring tokens. The message “ERC20: transfer amount exceeds allowance” is then returned to the user in the transaction receipt.

Requirements

• The revert reason must be configured on nodes. For instance on Hyperledger Besu, the --revert-reason-enabled option must be set.
• The smart contract to which transactions are sent must implement a revert reason on failure.

Read the revert reason

Orchestrate helps by decoding the revert reason and displays the clear message in the output. Simply retrieve the revertReason field of the receipt.

Decoded revert reason

The revertReason property in the transaction receipt JSON output has the decoded ERC20: transfer amount exceeds balance string value instead of the encoded raw value.