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This guide explains how to configure Decentralized Verifier Networks (DVNs), Executors, and message libraries for your IOTA OApp or OFT using the SDK.

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Overview

Configuration is done through the OApp SDK instance. All examples use sdk.getOApp(packageId) to get the OApp instance, then call SDK methods for configuration. Configuration flow:
  1. Set message libraries (optional)
  2. Configure DVNs for send/receive (optional but recommended)
  3. Set enforced options (optional)
  4. Set peer addresses (required - opens pathway, call last!)

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SDK Setup

import {SDK} from '@layerzerolabs/lz-iotal1-sdk-v2';
import {Stage} from '@layerzerolabs/lz-definitions';

const sdk = new SDK({client, stage: Stage.MAINNET});
const oapp = sdk.getOApp(yourPackageId); // Always use SDK factory

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Configuration Methods

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Set Peer

// Configure peer for destination chain
await oapp.setPeerMoveCall(tx, dstEid, peerBytes32);
Address format: Use package ID for IOTA peers, 32-byte address for other chains.

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Set Message Libraries

// Set custom send library
await oapp.setSendLibraryMoveCall(tx, dstEid, libraryAddress);

// Set custom receive library
await oapp.setReceiveLibraryMoveCall(tx, srcEid, libraryAddress, gracePeriod);
Default: Uses Endpoint defaults if not configured.

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DVN Configuration

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Configure Receive DVN (Inbound)

import {
  SDK,
  OAppUlnConfigBcs,
  PACKAGE_ULN_302_ADDRESS,
  OBJECT_ULN_302_ADDRESS,
  PACKAGE_DVN_LAYERZERO_ADDRESS,
} from '@layerzerolabs/lz-iotal1-sdk-v2';
import {Stage} from '@layerzerolabs/lz-definitions';

const sdk = new SDK({client, stage: Stage.MAINNET});
const oapp = sdk.getOApp(yourPackageId);

// Encode configuration
const config = OAppUlnConfigBcs.serialize({
  use_default_confirmations: false,
  use_default_required_dvns: false,
  use_default_optional_dvns: true,
  uln_config: {
    confirmations: 15,
    required_dvns: [PACKAGE_DVN_LAYERZERO_ADDRESS[Stage.MAINNET]],
    optional_dvns: [],
    optional_dvn_threshold: 0,
  },
}).toBytes();

// Two-step Call pattern
const tx = new Transaction();
const configCall = await oapp.setConfigMoveCall(
  tx,
  PACKAGE_ULN_302_ADDRESS[Stage.MAINNET],
  30184, // Remote EID
  3, // CONFIG_TYPE_RECEIVE_ULN
  config,
);

tx.moveCall({
  target: `${PACKAGE_ULN_302_ADDRESS[Stage.MAINNET]}::uln_302::set_config`,
  arguments: [tx.object(OBJECT_ULN_302_ADDRESS[Stage.MAINNET]), configCall],
});

await client.signAndExecuteTransaction({transaction: tx, signer: keypair});

​
Configure Send DVN (Outbound)

// Same pattern, use CONFIG_TYPE_SEND_ULN = 2
const configCall = await oapp.setConfigMoveCall(
  tx,
  PACKAGE_ULN_302_ADDRESS[Stage.MAINNET],
  30184,
  2, // CONFIG_TYPE_SEND_ULN
  config,
);
Config types: 1 = Executor, 2 = Send ULN, 3 = Receive ULN DVN addresses: Use PACKAGE_DVN_LAYERZERO_ADDRESS[Stage.MAINNET] or see Deployed Contracts.

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Set Enforced Options

import {Options} from '@layerzerolabs/lz-v2-utilities';

const options = Options.newOptions()
  .addExecutorLzReceiveOption(60000, 0) // Gas for destination
  .toBytes();

await oapp.setEnforcedOptionsMoveCall(tx, dstEid, msgType, options);

​
Gas Limit Recommendations

Based on gas profiling:

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OApp/OFT Operations

OperationGas Used (IOTA)Recommended BudgetNotes
lz_receive2,000-4,1723,500-5,000For OApps and custom business logic, this needs independent profiling
oft_send4,728,6206,700,000Includes endpoint + ULN
dvn_verify5,684,1087,700,000Verification submission
dvn_commit517,2482,500,000Commit verification

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Enforced Options Examples

For EVM destinations: 
import {Options} from '@layerzerolabs/lz-v2-utilities';

// Standard OApp message
const options = Options.newOptions()
  .addExecutorLzReceiveOption(60000, 0) // 60k gas, no msg.value
  .toBytes();

// OFT with compose
const optionsCompose = Options.newOptions()
  .addExecutorLzReceiveOption(200000, 0) // Higher for compose
  .toBytes();
For IOTA destinations: 
const optionsForIOTA = Options.newOptions()
  .addExecutorLzReceiveOption(5000, 0) // 5k gas units, no msg.value
  .toBytes();
Note: Based on gas profiling, IOTA lz_receive uses 2,000-5,000 gas units. No msg.value needed - IOTA handles storage internally.

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Common Issues

Errors:
  • InvalidBCSBytes → Use OAppUlnConfigBcs.serialize() for DVN config
  • oapp_registry::get_messaging_channel abort code: 1 → Used object ID instead of package ID as peer
  • Channel not initialized → Registration creates MessagingChannel automatically (no manual init needed)

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Next Steps