Monitoring deployed contracts in Blockchain / Solidity - Step-by-Step Execution

Concept Flow - Monitoring deployed contracts

Deploy Contract

↓

Get Contract Address

↓

Set Up Monitoring Tool

↓

Listen to Contract Events

↓

Receive Event Data

↓

Trigger Alerts or Logs

↓

Analyze Contract Behavior

↓

Repeat Monitoring Cycle

This flow shows how after deploying a contract, you get its address, set up monitoring, listen to events, and react to contract activity continuously.

Execution Sample

Blockchain / Solidity

const contract = new ethers.Contract(address, abi, provider);
contract.on('Transfer', (from, to, amount) => {
  console.log(`Transfer from ${from} to ${to} of ${amount.toString()}`);
});

This code listens for 'Transfer' events on a deployed contract and logs details when such events happen.

Execution Table

Step	Action	Evaluation	Result
1	Deploy contract	Contract deployed on blockchain	Contract address obtained
2	Initialize contract object	Using address and ABI	Contract instance ready
3	Set event listener for 'Transfer'	Listening for events	Waiting for events
4	Event 'Transfer' emitted	Event data: from=0xA, to=0xB, amount=100	Event handler triggered
5	Log event details	Console output	Printed: Transfer from 0xA to 0xB of 100
6	Continue listening	No new events yet	Idle, waiting for next event

💡 Monitoring continues indefinitely until stopped manually

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 4	Final
contractAddress	undefined	0x123...abc	0x123...abc	0x123...abc	0x123...abc
contractInstance	undefined	undefined	Contract Object	Contract Object	Contract Object
eventData	undefined	undefined	undefined	{from: '0xA', to: '0xB', amount: 100}	undefined

Key Moments - 3 Insights

Why do we need the contract address after deployment?

The contract address identifies the deployed contract on the blockchain. Without it, we cannot create a contract instance to listen for events, as shown in Step 2 of the execution_table.

What happens if no events are emitted after setting the listener?

The monitoring tool stays idle, waiting for events. This is shown in Step 6 where the system waits without output until an event occurs.

How does the event listener know when to trigger the callback?

When the blockchain emits an event matching the listener's filter (e.g., 'Transfer'), the callback runs automatically, as in Step 4 and 5.

Visual Quiz - 3 Questions

Look at the execution_table, what is the contractAddress value after Step 1?

A 0x123...abc

B undefined

C Contract Object

D Event data

💡 Hint

Check the variable_tracker row for contractAddress at After Step 1

At which step does the event handler get triggered?

A Step 3

B Step 5

C Step 4

D Step 6

💡 Hint

Look at the execution_table row where event data is received and handler runs

If the contract emits no events, what will the monitoring tool do?

A Throw an error

B Stay idle waiting for events

C Stop monitoring

D Restart the contract

💡 Hint

Refer to Step 6 in the execution_table showing the system waiting for events

Concept Snapshot

Monitoring deployed contracts:
1. Deploy contract and get its address.
2. Create contract instance with address and ABI.
3. Set event listeners for contract events.
4. On event, callback runs to log or alert.
5. Monitoring runs continuously until stopped.

Full Transcript

Monitoring deployed contracts involves first deploying the contract and obtaining its blockchain address. Then, a contract instance is created using this address and the contract's ABI. Event listeners are set up on this instance to listen for specific events like 'Transfer'. When such an event occurs, the listener triggers a callback function that logs or processes the event data. The monitoring process continues indefinitely, waiting for new events to react to.