Read & Decode

Components for reading on-chain state and decoding ABI-encoded data — without sending any transactions.

Avoid public RPC endpoints

White Rabbit runs on shared infrastructure with a shared outbound IP pool. Public RPC URLs enforce rate limits per IP — under load this can cause errors across all workspaces sharing that IP. Use a private endpoint (Alchemy, Infura, QuickNode, or self-hosted). See Connecting to any chain.

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READ_EVM_CONTRACT

READ_EVM_CONTRACT Workflow Component

Call a read-only (view / pure) contract function using eth_call. Returns the raw ABI-encoded result — pipe into DECODE_EVM_FUNCTION_RESULT to extract the values.

Config

None.

Inputs

Field	Type	Description
jsonRpcUrl	string	JSON-RPC endpoint
contractAddress	string	Target contract address
calldata	string	ABI-encoded calldata (from BUILD_EVM_CALLDATA)

Outputs

Field	Type	Description
result	string	Raw ABI-encoded return data (hex)

Example: read ERC-20 balance

BUILD_EVM_CALLDATA (balanceOf ABI, [holder_address])
        │ calldata
        ▼
READ_EVM_CONTRACT (jsonRpcUrl, token_contract)
        │ result
        ▼
DECODE_EVM_FUNCTION_RESULT (balanceOf ABI, result)
        │
        ▼ balance (uint256 as string)

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DECODE_EVM_FUNCTION_RESULT

DECODE_EVM_FUNCTION_RESULT Workflow Component

ABI-decode the raw bytes returned from a contract call into typed values.

Config

Field	Type	Required	Description
functionName	string	Yes	Name of the function whose return type should be used for decoding (e.g. "balanceOf")

Inputs

Field	Type	Description
abi	AbiItem[]	ABI containing the function definition
encodedResult	string	Raw hex-encoded return data (output of READ_EVM_CONTRACT)

Outputs

Outputs are dynamic — one output per return value in the function's ABI definition. They are indexed as 0, 1, 2, etc. (matching the order of outputs in the ABI).

Field	Type	Description
0	depends on ABI	First decoded return value
1	depends on ABI	Second decoded return value (if any)
...	depends on ABI	Additional return values

SDK example

import { WorkspaceClient, ComponentModule } from 'caller-sdk';
const workspace = new WorkspaceClient({ apiKey: process.env.WR_API_KEY! });

// 1. Encode balanceOf(address) call
const calldata = await workspace.call(ComponentModule.BUILD_EVM_CALLDATA, {
  abi: [{
    type: 'function',
    name: 'balanceOf',
    inputs: [{ name: 'account', type: 'address' }],
    outputs: [{ name: '', type: 'uint256' }],
    stateMutability: 'view',
  }],
  args: ['0xHolderAddress'],
}).promise();

// 2. Read contract
const raw = await workspace.call(ComponentModule.READ_EVM_CONTRACT, {
  jsonRpcUrl: 'https://eth-mainnet.g.alchemy.com/v2/KEY',
  contractAddress: '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48', // USDC
  calldata: calldata.calldata,
}).promise();

// 3. Decode
const decoded = await workspace.call(ComponentModule.DECODE_EVM_FUNCTION_RESULT, {
  abi: [/* same ABI */],
  encodedResult: raw.result,
}).promise();

console.log(decoded.decoded[0]); // "1000000" (1 USDC)

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EVM_KECCAK256

EVM_KECCAK256 Workflow Component

Compute the keccak256 hash of any hex-encoded data. Used for signature preimages, topic filters, and function selectors.

Config

None.

Inputs

Field	Type	Description
data	string	Hex-encoded data to hash (0x... or without prefix)

Outputs

Field	Type	Description
hash	string	keccak256 hash (0x..., 32 bytes)

SDK example

import { WorkspaceClient, ComponentModule } from 'caller-sdk';
const workspace = new WorkspaceClient({ apiKey: process.env.WR_API_KEY! });

const hash = await workspace.call(ComponentModule.EVM_KECCAK256, {
  data: '0x095ea7b3', // approve(address,uint256) selector input
}).promise();
console.log(hash.hash); // "0x..."