RPC API

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Overview

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Connection Methods

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HTTP/HTTPS

# Start node with HTTP RPC
tomo --rpc --rpcaddr 0.0.0.0 --rpcport 8545 --rpcapi "eth,net,web3"

• --rpc: Enable HTTP-RPC server
• --rpcaddr: HTTP-RPC server listening interface (default: “localhost”)
• --rpcport: HTTP-RPC server listening port (default: 8545)
• --rpcapi: API’s offered over HTTP-RPC interface
• --rpccorsdomain: Comma separated list of domains to accept cross-origin requests
• --rpcvhosts: Comma separated list of virtual hostnames to accept requests

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WebSocket

# Start node with WebSocket RPC
tomo --ws --wsaddr 0.0.0.0 --wsport 8546 --wsapi "eth,net,web3"

• --ws: Enable WS-RPC server
• --wsaddr: WS-RPC server listening interface (default: “localhost”)
• --wsport: WS-RPC server listening port (default: 8546)
• --wsapi: API’s offered over WS-RPC interface
• --wsorigins: Origins from which to accept websocket requests

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IPC (Inter-Process Communication)

# IPC endpoint is created automatically
# Default location: ~/.tomo/tomo.ipc

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API Namespaces

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eth (Ethereum Compatible)

• eth_blockNumber: Get latest block number
• eth_getBalance: Get account balance
• eth_getBlockByNumber: Get block by number
• eth_getBlockByHash: Get block by hash
• eth_getTransactionByHash: Get transaction details
• eth_getTransactionReceipt: Get transaction receipt
• eth_sendRawTransaction: Send signed transaction
• eth_call: Execute read-only contract call
• eth_estimateGas: Estimate gas for transaction
• eth_getLogs: Get event logs
• eth_subscribe: Subscribe to events (WebSocket only)

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net

• net_version: Get network ID
• net_listening: Check if client is listening
• net_peerCount: Get number of connected peers

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web3

• web3_clientVersion: Get client version
• web3_sha3: Calculate Keccak-256 hash

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personal

• personal_newAccount: Create new account
• personal_unlockAccount: Unlock account
• personal_sendTransaction: Send transaction
• personal_sign: Sign data

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txpool

• txpool_content: Get pending and queued transactions
• txpool_inspect: Inspect transaction pool
• txpool_status: Get transaction pool status

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debug

• debug_traceTransaction: Trace transaction execution
• debug_traceBlock: Trace block execution
• debug_getBlockRlp: Get RLP-encoded block

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Making RPC Calls

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Using cURL

# Get latest block number
curl -X POST \
  -H "Content-Type: application/json" \
  --data '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":1}' \
  http://localhost:8545

# Get balance
curl -X POST \
  -H "Content-Type: application/json" \
  --data '{"jsonrpc":"2.0","method":"eth_getBalance","params":["0x...","latest"],"id":1}' \
  http://localhost:8545

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Using JavaScript (Node.js)

const axios = require('axios');

async function getBlockNumber() {
  const response = await axios.post('http://localhost:8545', {
    jsonrpc: '2.0',
    method: 'eth_blockNumber',
    params: [],
    id: 1
  });
  
  console.log('Block number:', parseInt(response.data.result, 16));
}

getBlockNumber();

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RPC Server Implementation

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Server Features

• Concurrent Request Handling: Multiple requests processed simultaneously
• Out-of-Order Responses: Responses can be sent back in any order
• Multiple Codecs: JSON-RPC over HTTP, WebSocket, and IPC
• Service Registration: Dynamic method registration
• Publish/Subscribe: Real-time event subscriptions

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Method Requirements

1. Object must be exported
2. Method must be exported
3. Method returns 0, 1 (response or error), or 2 (response and error) values
4. Method arguments must be exported or builtin types
5. Method return values must be exported or builtin types

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Example Service

type CalculatorService struct {}

func (s *CalculatorService) Add(a, b int) int {
    return a + b
}

func (s *CalculatorService) Div(a, b int) (int, error) {
    if b == 0 {
        return 0, errors.New("divide by zero")
    }
    return a/b, nil
}

// Register the service
server := rpc.NewServer()
server.RegisterName("calculator", new(CalculatorService))

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Subscriptions (WebSocket)

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Available Subscriptions

• newHeads: New block headers
• logs: Event logs matching filter criteria
• newPendingTransactions: New pending transactions
• syncing: Sync status changes

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Subscription Example

const Web3 = require('web3');
const web3 = new Web3('ws://localhost:8546');

// Subscribe to new blocks
web3.eth.subscribe('newBlockHeaders', (error, blockHeader) => {
  if (!error) {
    console.log('New block:', blockHeader.number);
  }
});

// Subscribe to logs
web3.eth.subscribe('logs', {
  address: '0x...', // Contract address
  topics: ['0x...']  // Event signature
}, (error, log) => {
  if (!error) {
    console.log('New log:', log);
  }
});

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Rate Limiting and Security

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Best Practices

1. Never expose personal API publicly: personal namespace should only be used locally
2. Use HTTPS in production: Encrypt RPC traffic
3. Implement rate limiting: Use reverse proxy (nginx, HAProxy)
4. Restrict API methods: Only enable necessary namespaces
5. Configure CORS carefully: Restrict origins in --rpccorsdomain
6. Use firewall rules: Limit access to RPC ports

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Production Configuration

tomo \
  --rpc --rpcaddr 127.0.0.1 --rpcport 8545 \
  --rpcapi "eth,net,web3" \
  --rpccorsdomain "https://yourdapp.com" \
  --ws --wsaddr 127.0.0.1 --wsport 8546 \
  --wsapi "eth,net,web3" \
  --wsorigins "https://yourdapp.com"

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Batch Requests

const batch = new web3.BatchRequest();

batch.add(web3.eth.getBalance.request('0x...', 'latest', callback));
batch.add(web3.eth.getTransactionCount.request('0x...', 'latest', callback));

batch.execute();

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Error Handling

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Common Error Codes

• -32700: Parse error
• -32600: Invalid request
• -32601: Method not found
• -32602: Invalid params
• -32603: Internal error
• -32000: Server error (custom)

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Example Error Response

{
  "jsonrpc": "2.0",
  "id": 1,
  "error": {
    "code": -32601,
    "message": "Method not found"
  }
}

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Performance Optimization

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Connection Management

• Keep-Alive: HTTP connections use TCP keep-alive (30s interval)
• Timeout Settings: Default dial timeout is 10s, write timeout is 10s
• Subscription Buffer: Max buffer size is 8000 items

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Payload Limits

• Max Request Size: 128KB (131,072 bytes)
• Max WebSocket Payload: Configurable per connection

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Public RPC Endpoints

• HTTP: https://rpc.viction.xyz
• WebSocket: wss://ws.viction.xyz

• HTTP: https://rpc-testnet.viction.xyz
• WebSocket: wss://ws-testnet.viction.xyz

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Next Steps

• Web3 Integration Guide
• Testing and Development
• Smart Contract Development