Scratchpad

Scratchpad is a native data type in the Autonomi Network:

Key-addressed: Network address is derived from a BLS public key
Size: Up to 4MB mutable storage
Pay-once, free updates: Unlimited updates for free after initial payment
Versioned & signed: Includes a version counter and cryptographically verifiable signatures
Encrypted: Content is automatically encrypted with the owner's key

Client Methods

scratchpad_get_from_public_key

Retrieves a scratchpad from the network using the owner's public key.

Input:

public_key: &PublicKey - The owner's public key

Output:

Rust: Result<Scratchpad, ScratchpadError>
Python: Scratchpad or raises exception
Node.js: Promise<Scratchpad>

scratchpad_get

Retrieves a scratchpad from the network by its address.

Input:

address: &ScratchpadAddress - The scratchpad address

Output:

Rust: Result<Scratchpad, ScratchpadError>
Python: Scratchpad or raises exception
Node.js: Promise<Scratchpad>

scratchpad_check_existence

Checks if a scratchpad exists on the network. Much faster than scratchpad_get.

Input:

address: &ScratchpadAddress - The scratchpad address

Output:

Rust: Result<bool, ScratchpadError>
Python: bool or raises exception
Node.js: Promise<boolean>

scratchpad_verify

Verifies a scratchpad's signature and size constraints.

Input:

scratchpad: &Scratchpad - The scratchpad to verify

Output:

Rust: Result<(), ScratchpadError>
Python: None or raises exception
Node.js: void (throws on error)

scratchpad_put

Manually uploads a scratchpad to the network. Requires the scratchpad to be already created and signed.

Input:

scratchpad: Scratchpad - The scratchpad to store
payment_option: PaymentOption - Payment method

Output:

Rust: Result<(AttoTokens, ScratchpadAddress), ScratchpadError>
Python: tuple[str, ScratchpadAddress] (cost as string) or raises exception
Node.js: Promise<ScratchpadPut> with cost: string and addr: ScratchpadAddress

scratchpad_create

Creates and uploads a new scratchpad to the network. Encrypts the content automatically.

Input:

owner: &SecretKey - The owner's secret key
content_type: u64 - Application-specific content type identifier
initial_data: &Bytes - The initial data to store
payment_option: PaymentOption - Payment method

Output:

Rust: Result<(AttoTokens, ScratchpadAddress), ScratchpadError>
Python: tuple[str, ScratchpadAddress] (cost as string) or raises exception
Node.js: Promise<ScratchpadPut> with cost: string and addr: ScratchpadAddress

scratchpad_update

Updates an existing scratchpad with new content. This operation is free.

Input:

owner: &SecretKey - The owner's secret key
content_type: u64 - Content type identifier
data: &Bytes - The new data to store

Output:

Rust: Result<(), ScratchpadError>
Python: None or raises exception
Node.js: Promise<void>

scratchpad_update_from

Updates an existing scratchpad from a specific scratchpad instance. Used internally by scratchpad_update.

Input:

current: &Scratchpad - The current scratchpad
owner: &SecretKey - The owner's secret key
content_type: u64 - Content type identifier
data: &Bytes - The new data to store

Output:

Rust: Result<Scratchpad, ScratchpadError>
Python: Scratchpad or raises exception
Node.js: Not directly exposed

scratchpad_cost

Estimates the storage cost for a new scratchpad.

Input:

owner: &PublicKey - The owner's public key

Output:

Rust: Result<AttoTokens, CostError>
Python: str (cost as string) or raises exception
Node.js: Promise<string>

Language-Specific Type Differences

Error Handling

Rust: Uses Result<T, ScratchpadError> with detailed error variants
Python: Raises exceptions with simplified error messages as strings
Node.js: Uses Promise rejection with Error objects containing simplified messages

Numeric Types

Rust: Uses u64 for content_type, AttoTokens for costs
Python: Uses int for content_type, str for costs
Node.js: Uses bigint for content_type, string for costs

Data Types

Rust: Uses Bytes type for data
Python: Uses bytes for data
Node.js: Uses Buffer for data

Examples

use autonomi::{Client, SecretKey, AttoTokens, Bytes};
use autonomi::client::payment::PaymentOption;

async fn scratchpad_example() -> Result<(), Box<dyn std::error::Error>> {
    // Initialize client and wallet
    let client = Client::init_local().await?;
    let wallet = get_funded_wallet();
    let payment = PaymentOption::from(&wallet);

    // Create secret key for scratchpad
    let key = SecretKey::random();
    let public_key = key.public_key();
    
    // Check cost
    let cost = client.scratchpad_cost(&public_key).await?;
    println!("Scratchpad cost: {}", cost);

    // Create scratchpad
    let content_type = 42;
    let initial_data = Bytes::from("Hello, Autonomi!");
    let (cost, addr) = client
        .scratchpad_create(&key, content_type, &initial_data, payment.clone())
        .await?;
    println!("Created at {:?}, cost: {}", addr, cost);

    // Get scratchpad
    let scratchpad = client.scratchpad_get(&addr).await?;
    assert_eq!(scratchpad.counter(), 0);
    
    // Decrypt content
    let decrypted = scratchpad.decrypt_data(&key)?;
    assert_eq!(decrypted, initial_data);

    // Update scratchpad
    let new_data = Bytes::from("Updated content!");
    client.scratchpad_update(&key, content_type, &new_data).await?;

    // Get updated scratchpad
    let updated = client.scratchpad_get(&addr).await?;
    assert_eq!(updated.counter(), 1);
    let updated_content = updated.decrypt_data(&key)?;
    assert_eq!(updated_content, new_data);

    Ok(())
}

import asyncio
from autonomi_client import Client, SecretKey, Wallet, PaymentOption, Network

async def scratchpad_example():
    # Initialize client and wallet
    client = await Client.init_local()
    network = Network(True)
    private_key = "0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80"
    wallet = Wallet.new_from_private_key(network, private_key)
    payment = PaymentOption.wallet(wallet)

    # Create secret key for scratchpad
    key = SecretKey()
    public_key = key.public_key()

    try:
        # Check cost
        cost = await client.scratchpad_cost(public_key)
        print(f"Scratchpad cost: {cost}")

        # Create scratchpad
        content_type = 42
        initial_data = b"Hello, Autonomi!"
        cost, addr = await client.scratchpad_create(key, content_type, initial_data, payment)
        print(f"Created at {addr.hex}, cost: {cost}")

        # Get scratchpad
        scratchpad = await client.scratchpad_get(addr)
        assert scratchpad.counter() == 0
        
        # Decrypt content
        decrypted = scratchpad.decrypt_data(key)
        assert decrypted == initial_data

        # Update scratchpad (free)
        new_data = b"Updated content!"
        await client.scratchpad_update(key, content_type, new_data)

        # Get updated scratchpad
        updated = await client.scratchpad_get(addr)
        assert updated.counter() == 1
        updated_content = updated.decrypt_data(key)
        assert updated_content == new_data

    except Exception as e:
        print(f"Error: {e}")

asyncio.run(scratchpad_example())

import { Client, SecretKey, Wallet, Network, PaymentOption } from '@withautonomi/autonomi';

async function scratchpadExample() {
    try {
        // Initialize client and wallet
        const client = await Client.initLocal();
        const network = new Network(true);
        const privateKey = "0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80";
        const wallet = Wallet.newFromPrivateKey(network, privateKey);
        const payment = PaymentOption.fromWallet(wallet);

        // Create secret key for scratchpad
        const key = SecretKey.random();
        const publicKey = key.publicKey();

        // Check cost
        const cost = await client.scratchpadCost(publicKey);
        console.log(`Scratchpad cost: ${cost}`);

        // Create scratchpad
        const contentType = 42n;
        const initialData = Buffer.from("Hello, Autonomi!");
        const { cost: createCost, addr } = await client.scratchpadCreate(key, contentType, initialData, payment);
        console.log(`Created at ${addr.toHex()}, cost: ${createCost}`);

        // Get scratchpad
        const scratchpad = await client.scratchpadGet(addr);
        console.assert(scratchpad.counter() === 0n);
        
        // Decrypt content
        const decrypted = scratchpad.decryptData(key);
        console.assert(Buffer.compare(decrypted, initialData) === 0);

        // Update scratchpad (free)
        const newData = Buffer.from("Updated content!");
        await client.scratchpadUpdate(key, contentType, newData);

        // Get updated scratchpad
        const updated = await client.scratchpadGet(addr);
        console.assert(updated.counter() === 1n);
        const updatedContent = updated.decryptData(key);
        console.assert(Buffer.compare(updatedContent, newData) === 0);

        console.log("Scratchpad operations completed successfully!");

    } catch (error) {
        console.error('Error:', error.message);
    }
}

scratchpadExample();

Error Handling

Rust Errors

The ScratchpadError enum provides detailed error variants:

PutError - Failed to store scratchpad
Pay - Payment failure
GetError - Failed to retrieve scratchpad
Corrupt - Invalid scratchpad data
Serialization - Serialization error
ScratchpadAlreadyExists - Scratchpad already exists at address
CannotUpdateNewScratchpad - Cannot update non-existent scratchpad
ScratchpadTooBig - Exceeds maximum size (4MB)
BadSignature - Invalid signature
Fork - Multiple conflicting versions detected

Python Error Handling

try:
    scratchpad = await client.scratchpad_get(addr)
except Exception as e:
    if "RecordNotFound" in str(e):
        print("Scratchpad does not exist")
    elif "BadSignature" in str(e):
        print("Invalid scratchpad signature")
    else:
        print(f"Unexpected error: {e}")

Node.js Error Handling

try {
    const scratchpad = await client.scratchpadGet(addr);
} catch (error) {
    if (error.message.includes('RecordNotFound')) {
        console.log('Scratchpad does not exist');
    } else if (error.message.includes('BadSignature')) {
        console.log('Invalid scratchpad signature');
    } else {
        console.error('Unexpected error:', error.message);
    }
}

Due to compatibility issues, Python and Node.js bindings simplify types (and error types to string messages within exceptions/rejections). For full experience and control it's recommended to use Rust.

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Last updated 3 months ago