Aggregate Transaction

Aggregated Transactions merge multiple transactions into one, allowing trustless swaps, and other advanced logic. NEM does this by generating a one-time disposable smart contract. When all involved accounts have cosigned the aggregate transaction, all the inner transactions are executed at the same time.

Aggregate complete

An aggregate transaction is complete when all the required participants have signed it.

The cosigners can sign the transaction without using the blockchain. Once it has all the required signatures, one of them can announce it to the network. If the inner transaction setup is valid, and there is no validation error, the transactions will get executed at the same time.

Aggregate complete transactions enable adding more transactions per block by gathering multiple inner transactions.

Sending payouts

Dan announces an aggregate transaction that merges two transfer transactions.

As he is the only required signatory, the transaction is considered complete after he signed. After announcing it to the network, Alice and Bob will receive the mosaics at the same time.

../_images/aggregate-sending-payouts.png

Sending payouts with aggregate complete transactions

Aggregate bonded

An aggregate transaction is bonded when it requires signatures from other participants.

Note

Before sending an aggregate bonded transaction, an account must first announce a hash lock transaction and get its confirmation with at least 10 cat.currency.

Once an aggregate bonded is announced, it reaches partial state and notifies its status through WebSockets or HTTP API calls.

Every time a cosignatory signs the transaction and announces an aggregate bonded cosignature, the network checks if all the required cosigners have signed. When all signatures are acquired, the transaction changes to unconfirmed state until the network includes it in a block.

../_images/aggregate-bonded-transaction-cycle.png

Aggregate bonded transaction cycle

Multi-Asset Escrowed Transactions

In this example, Alice is buying tickets with currency.euro mosaic. When the ticket distributor cosigns the aggregate transaction, the swap will happen atomically.

../_images/aggregate-escrow-1.png

Multi-Asset Escrowed Transactions

Paying for others fees

Alice sends 10 currency.euro to Bob using an app to make payments. But she doesn’t have any cat.currency to pay the blockchain transaction fee.

By creating an aggregate bonded transaction, she can convert EUR to cat.currency to pay the fee. Now Alice and Bob can use NEM blockchain without ever having to buy or hold cat.currency.

Since the app creator can put their own branding on the open source payment app, Alice and Bob may not even know they are using blockchain.

../_images/aggregate-paying-for-others-fees.png

Paying for others fees

Guides

Schemas

Note

Configuration parameters are editable . Public network configuration may differ.

AggregateTransaction

Version: 0x02

Entity type: 0x4141 (complete), 0x4241 (bonded)

Inlines:

Transaction

Property Type Description
payloadSize uint32 The transaction payload size in bytes. In other words, the total number of bytes occupied by all inner transactions.
transactions array(byte, payloadSize) The array of transactions initiated by different accounts. An aggregate transaction can contain up to 1000 inner transactions involving up to 15 different cosignatories. Other aggregate transactions are not allowed as inner transactions.
cosignatures array(byte, size - payloadSize) An array of transaction cosignatures.

DetachedCosignature

Cosignature transactions are used to sign announced aggregate bonded transactions with missing cosignatures.

Inlines:

Property Type Description
parentHash 32 bytes (binary) The aggregate bonded transaction hash to cosign.

Cosignature

Property Type Description
signer 32 bytes (binary) The cosigner public key.
signature 64 bytes (binary) The transaction signature.

HashLockTransaction

Alias: LockFundsTransaction

Announce a hash lock transaction before sending a signed aggregate bonded transaction to prevent network spamming.

Once the related aggregate bonded transaction is confirmed, the locked funds become available in the account that signed the initial hash lock transaction.

If the aggregate bonded transaction duration is reached without being signed by all cosignatories, the locked amount is collected by the block harvester at the height where the lock expires.

Version: 0x01

Entity type: 0x4148

Inlines:

Property Type Description
mosaic Mosaic Locked mosaic, must be at least 10 cat.currency.
duration uint64 The lock duration.
hash 32 bytes (binary) The aggregate bonded transaction hash that has to be confirmed before unlocking the mosaics.