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LOG

Supported Network​

Network

Supporting

Ethereum Mainnet

✅

Ethereum Testnet (sepolia)

✅

Ethereum Testnet (holesky)

✅

Polygon Mainnet

✅

Polygon Testnet (amoy)

✅

Arbitrum Mainnet

✅

Arbitrum Testnet (sepolia)

✅

Optimism Mainnet

✅

Optimism Testnet (sepolia)

✅

Kaia Mainnet

✅

Kaia Testnet (kairos)

✅

Aptos Mainnet

❌

Aptos Testnet

❌



Conditions

When eventType is set to LOG, the available condition object fields are listed below.

Key

Type

Description

Required

Example Value

address

String

Contract address where the event to monitor is defined.

true

0xdAC17F958D2ee523a2206206994597C13D831ec7

topics[4]

Array of String

Topic array object for the event log to monitor. Can contain up to 4 strings.

true

["0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef",
"0x000000000000000000000000b7aa2d3c833a6827c4f39bef9622d7cddf66b7e7",
"0x0000000000000000000000003264039cfaa37a70a0e8ccfbf4b7e60bedce5c9f"]

Important notes when using the Topics field

When entering data of the Address type in an event signature, the value must be provided in Hex Format, not decoded format.

I have an event log I want to monitor. What value should I put in the Topic field?

The Topic field for the event you want to monitor is used to filter data associated with smart contract events. Each topic contains the event signature and indexed parameter information for the event.

topics[0]: Event Signature

  • topics[0] is always the Keccak256 hash of the event signature.
    For example, for the Transfer(address indexed from, address indexed to, uint256 value) event, the event signature can be obtained by running the following:
    Keccak256("Transfer(address,address,uint256)")
    = 0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef

topics[1], topics[2], topics[3]: Indexed Parameters

  • Starting from topics[1], each entry corresponds to an indexed parameter value of the event. Only event parameters declared with the indexed keyword in the smart contract are included in the topics. For the Transfer event above, the from address corresponds to topics[1] and the to address corresponds to topics[2]. To filter only events where a specific address appears as the from address, enter that address value in topics[1]. The remaining non-indexed parameters can be found in the data field of the retrieved log.

How to find Topic values

  • From the smart contract code: Identify the event definition in the Solidity code, locate the indexed parameters and event signature, then compute the topic value using Keccak256 hashing.
  • Using a block explorer: Select a sample transaction to trace, navigate to the transaction detail, and find the topic values in the "Logs" section. Below is an example screen from Etherscan (https://etherscan.io) showing the log for a USDC (ERC20) Transfer event.

Response Example​

subscription_connected The user(8350954814192461336) is connected. 
registered messageId: 123,
subscriptionId: 5096
subscription Event :  subscriptionId: 5096,
  eventType: LOG,
  event: {
  "targetAddress": "0xdAC17F958D2ee523a2206206994597C13D831ec7",
  "topics": [
    "0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef"
  ],
  "messages": [
    {
      "address": "0xdac17f958d2ee523a2206206994597c13d831ec7",
      "topics": [
        "0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef",
        "0x0000000000000000000000009696f59e4d72e237be84ffd425dcad154bf96976",
        "0x000000000000000000000000586197da4971fadf8604b8fd81f2a576032402d2"
      ],
      "data": "0x0000000000000000000000000000000000000000000000000000009e52bdc040",
      "block_number": 21570934,
      "transaction_hash": "0x905de51ac1f611942343d1a4b9b913bd392b5b3bcb100f22167ef2670a36df18",
      "transaction_index": 10,
      "log_index": 22,
      "block_hash": "0xc3f7d16da3dd3649e20dfec4346b2a967f9ff369b770d1e1f979fbe58e77e8ce",
      "block_timestamp": 1736232887,
      "removed": false,
      "type": "log"
    }
  ]
}