Library for Scheduled Neon EVM Transaction

Note: this package is under development, run on neon test environment and is not ready for production use.

How to install and run tests

yarn install
cd packages/core
yarn test
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How to using it in code

Node: for more details run yarn test in packages/core folder and see solana-signer.spec.ts file.

First, it is necessary to initialize all variables and providers for Solana and Neon EVM RPCs.

const result = await getProxyState(`<neon_proxy_rpc_url>`);
const token = getGasToken(result.tokensList, NeonChainId.testnetSol);
const connection = new Connection(`<solana_rpc_url>`, 'confirmed');
const provider = new JsonRpcProvider(`<neon_proxy_rpc_url>`);
const neonClientApi = new NeonClientApi(`<neon_client_api_url>`);
const neonProxyRpcApi = result.proxyApi;
const neonEvmProgram = result.evmProgramAddress;
const chainId = Number(token.gasToken.tokenChainId);
const chainTokenMint = new PublicKey(token.gasToken.tokenMint);
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Next, connect a Solana wallet (in this example, a Keypair is used, but any other method for signing and sending transactions on the Solana network can also be used).

The SolanaNeonAccount class includes the Solana wallet, calculates the Neon wallet, and manages the balance account required for creating a Scheduled transaction and executing transactions on the Neon EVM.

const solanaPrivateKey = bs58.decode(`<you_private_key_base58>`);
const keypair = Keypair.fromSecretKey(solanaPrivateKey);
const solanaUser = SolanaNeonAccount.fromKeypair(keypair, neonEvmProgram, chainTokenMint, chainId);
await solanaAirdrop(connection, solanaUser.publicKey, 1e9);
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We create a Scheduled transaction and send it, embedding the contract address and the method call data. Additionally, we retrieve the nonce for the Neon wallet and include this information in the Scheduled transaction.

const nonce = Number(await neonProxyRpcApi.getTransactionCount(solanaUser.neonWallet));
const maxFeePerGas = 0x77359400;

const scheduledTransaction = new ScheduledTransaction({
  nonce: toBeHex(nonce),
  payer: solanaUser.neonWallet,
  target: `<contract_address>`,
  callData: `<call_contract_data>`,
  maxFeePerGas: toBeHex(maxFeePerGas),
  chainId: toBeHex(NeonChainId.testnetSol)
});
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We create a transaction for Solana, including all the previously defined data.

const transaction = await createScheduledNeonEvmTransaction({
  chainId,
  signerAddress: solanaUser.publicKey,
  tokenMintAddress: solanaUser.tokenMint,
  neonEvmProgram,
  neonWallet: solanaUser.neonWallet,
  neonWalletNonce: nonce,
  neonTransaction: scheduledTransaction.serialize()
});
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It is necessary to ensure that the balance account is initialized on Solana before the Scheduled transaction is executed. If it is not, an instruction to create the balance account must be added.

const account = await connection.getAccountInfo(solanaUser.balanceAddress);

if (account === null) {
  transaction.instructions.unshift(createBalanceAccountInstruction(neonEvmProgram, solanaUser.publicKey, solanaUser.neonWallet, solanaUser.chainId));
}
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Sign and send the transaction to the Solana network.

const { blockhash, lastValidBlockHeight } = await connection.getLatestBlockhash();
transaction.recentBlockhash = blockhash;
transaction.sign({ publicKey: solanaUser.publicKey, secretKey: solanaUser.keypair });
const signature = await connection.sendRawTransaction(transaction.serialize());
console.log('Transaction signature', signature);
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Wait for the Scheduled transaction to execute on the Neon EVM and display the results.

const [transaction] = await neonClientApi.waitTransactionTreeExecution(solanaUser.neonWallet, nonce, 5e3);
const { status, transaction_hash, result_hash } = transaction;
console.log(`Scheduled transaction result`, transaction);
console.log(await neonProxyRpcApi.getTransactionReceipt(`0x${transaction_hash}`));
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Creating Multiple Scheduled Transactions

Multiple Scheduled Transactions is an advanced use case for creating a ScheduledTransaction.

For example, you may need to execute three transactions that call contract methods with different parameters and are executed sequentially, or where one depends on the completion of the other two. Alternatively, a transaction may involve a large volume of data that exceeds the limits of a single transaction permissible within the Solana network.

To create a MultipleTransactions, you need to instantiate the MultipleTransactions class with a common nonce, maxFeePerGas, and maxPriorityFeePerGas. At the same time, maxFeePerGas must match the value that will be passed to each ScheduledTransaction. After that, you can add individual transactions to the MultipleTransactions instance.

const multiple = new MultipleTransactions(nonce, maxFeePerGas);
const transaction = new ScheduledTransaction({
  nonce: nonce,
  payer: solanaUser.neonWallet,
  index: 0,
  target: baseContract.address,
  callData: baseContract.transactionData(solanaUser.publicKey),
  maxFeePerGas: maxFeePerGas,
  chainId: NeonChainId.testnetSol
});
multiple.addTransaction(transaction, NO_CHILD_INDEX, 0);
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The addTransaction method accepts three parameters:

• transaction: The Scheduled transaction to be added.
• childIndex: The index of child transactions that must be executed before this transaction starts. If the transaction has no dependent child transactions, the constant NO_CHILD_INDEX is passed.
• successLimit: The number of successful transactions that must be completed before this transaction starts execution.

After adding all necessary transactions, you need to create a multiple transaction for Solana and send it for execution.

const createScheduledTransaction = await createScheduledNeonEvmMultipleTransaction({
  chainId,
  neonEvmProgram,
  neonTransaction: multiple.data,
  signerAddress: solanaUser.publicKey,
  tokenMintAddress: solanaUser.tokenMint,
  neonWallet: solanaUser.neonWallet,
  neonWalletNonce: nonce
});
await sendSolanaTransaction(connection, createScheduledTransaction, [solanaUser.signer!], true, { skipPreflight }, 'scheduled');
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At this stage, you need to pass the Scheduled transaction to a specific method in the Neon Proxy RPC. If everything is done correctly, the Neon Proxy RPC will return the hash of the transaction.

const {result} = await neonProxyRpcApi.sendRawScheduledTransaction(`0x${transaction.serialize()}`);
console.log(result === transaction.hash());
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Next, you need to wait for the transaction to be executed.

const transactions = await neonClientApi.waitTransactionTreeExecution(solanaUser.neonWallet, nonce, 5e3);
console.log(`Scheduled transactions result`, transactions);
for (const { transaction_hash, status } of transactions) {
  const { result } = await neonProxyRpcApi.getTransactionReceipt(`0x${transaction_hash}`);
  console.log(result);
}
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By following these steps, you can create and execute a batch of Multiple Scheduled Transactions on Solana using Neon Proxy RPC.

Building Docs

We can run TypeDoc with packages mode to generate a single docs folder in the root of the project.

# We need to build before building the docs so that `foo` can reference types from `bar`
# TypeDoc can't use TypeScript's build mode to do this for us because build mode may skip
# a project that needs documenting, or include packages that shouldn't be included in the docs
yarn build:all
# or
npm run build:all
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Now, we can run TypeDoc with packages mode to generate a single docs folder

yarn build:docs
# or
npm run build:docs
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