Websocket API Guide for OKTC: Ethereum-Compatible Subscriptions

OKTC leverages Tendermint Core as its consensus engine and is built on the Cosmos SDK framework. While inheriting Tendermint's event format, OKTC adapts these responses to Ethereum-compatible types to support Web3 websocket functionality via Ethereum's PubSub API. This guide covers WebSocket setup, subscriptions, and supported events.

Getting Started with Websockets

To initiate an Ethereum-compatible WebSocket connection:

1. Start the REST server using the --wsport flag (default port: 8546)
2. Use a WebSocket client like ws to establish a connection

👉 Explore OKTC's developer tools for seamless integration.

Mainnet Websocket Endpoint

Connect to: wss://mainnet.oktc.io/ws (replace with actual OKTC mainnet URL)

Managing Subscriptions

Creating Subscriptions

Use eth_subscribe RPC call with:

• Method: eth_subscribe

• Parameters:

  1. Subscription name (e.g., newHeads)
  2. Optional filter criteria

Example Request:

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "eth_subscribe",
  "params": ["logs", {"address": "0x00..."}]
}

Canceling Subscriptions

Use eth_unsubscribe with:

• Method: eth_unsubscribe
• Parameters: Subscription ID

Example Request:

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "eth_unsubscribe",
  "params": ["0xab12..."]
}

Supported Subscription Types

1. New Block Headers (newHeads)

Triggers on new chain headers, including reorganizations.

Parameters: None
Example Output:

{
  "jsonrpc": "2.0",
  "method": "eth_subscription",
  "params": {
    "subscription": "0xab12...",
    "result": {
      "number": "0x1b4",
      "hash": "0x00...",
      "parentHash": "0x00..."
    }
  }
}

2. Logs

Filters and streams contract events.

Parameters:

• address: Single or array of contract addresses
• topics: Event signature filters

Example:

{
  "address": ["0x00..."],
  "topics": ["0x00..."]
}

3. Pending Transactions (newPendingTransactions)

Emits hashes of signed transactions entering mempool.

Parameters: None
Example Output: Transaction hash string

4. Sync Status (syncing)

Tracks node synchronization state.

Parameters: None
Output: Boolean or sync progress object

FAQs

Q: What's the difference between Tendermint and Ethereum WebSocket events?

A: OKTC translates Tendermint's native events into Ethereum-compatible formats for Web3 tooling interoperability.

Q: Can I filter logs by multiple contracts?

A: Yes, pass an array of addresses in the address parameter.

Q: How are chain reorganizations handled?

A: For logs subscriptions, removed logs include "removed": true. For newHeads, new canonical chain headers emit normally.

👉 Need advanced WebSocket configurations? Check OKTC's developer portal.

Best Practices

• Always handle removed flags in log events during reorgs
• Specify precise topic filters to reduce bandwidth
• Implement reconnection logic for stable long-running subscriptions

This implementation combines Cosmos SDK efficiency with Ethereum developer familiarity, enabling seamless dApp integration.