site/_src/_guides/tutorial-token-launch.md

layout	title	tagline	header
guide	Tutorial: Token distribution launch	Build a token launch with BigchainDB	header-token.jpg

You will learn:

• How BDB can be used to record the transactions made by a token distribution launch

• How to use divisible assets on BigchainDB

We show, how divisible assets work in BigchainDB by showing, how you could create your own token launch on BigchainDB. The token distribution is represented by divisible assets (tokens) linked to one specific application (company/network).

When creating a divisible asset in BigchainDB, the number of the sub-assets that you want to create should be specified.

Create divisible asset

const nTokens = 10000
let tokensLeft

function tokenLaunch() {

    const tx = BigchainDB.Transaction.makeCreateTransaction({
            token: tokenName.value,
            number_tokens: nTokens
        }, {
            datetime: new Date().toString()
        }, [BigchainDB.Transaction.makeOutput(BigchainDB.Transaction.makeEd25519Condition(tokenCreator.publicKey), nTokens.toString())],
        tokenCreator.publicKey
    )

    // Sign the transaction with private keys
    const txSigned = BigchainDB.Transaction.signTransaction(tx, tokenCreator.privateKey)

    conn.postTransaction(txSigned)
        .then(() => conn.pollStatusAndFetchTransaction(txSigned.id))
        .then(res => {
            lastTx = txSigned.id
            console.log('Create Transaction', txSigned, 'accepted')
            tokensLeft = nTokens
        })
}

We have decided to create 10000 tokens. For that there is an extra parameter to the makeOutput() function. Pay attention to give the function a String instead of a plain Number. With the tokenCreator keypair we indicate who the owner of the tokens will be. Once the transaction is accepted by BDB we update the value of the tokens left in the possesion of the creator.

Once the tokens are created we can start to spread it over our users.

Transfer tokens

const amountToSend = 200

function transferTokens() {
    const newUser = new BigchainDB.Ed25519Keypair()

    conn.listOutputs(tokenCreator.publicKey, 'false')
        .then((txs) => {
            conn.getTransaction(txs[0].transaction_id)
                .then((tx) => {
                    console.log('the search found', tx)

                    const createTranfer = BigchainDB.Transaction.makeTransferTransaction(
                        tx, {
                            tranferTo: 'john'
                        }, [BigchainDB.Transaction.makeOutput(
                                BigchainDB.Transaction.makeEd25519Condition(tokenCreator.publicKey), (tokensLeft - amountToSend).toString()),
                            BigchainDB.Transaction.makeOutput(
                                BigchainDB.Transaction.makeEd25519Condition(newUser.publicKey), amountToSend)
                        ],
                        0
                    )
                    const signedTransfer = BigchainDB.Transaction.signTransaction(createTranfer, tokenCreator.privateKey)
                    conn.postTransaction(signedTransfer)
                        .then(() => conn.pollStatusAndFetchTransaction(signedTransfer.id))
                        .then(res => {
                            tokensLeft -= amountToSend
                            console.log('Transfer Transaction', signedTransfer.id, 'accepted')
                        })
                })
        })
}

With listOutputs using false as the second argument we can retrieve all the outputs that were not spent yet. Then we query for that transaction and we make a transfer with it. As the transaction model of BigchainDB is designed, all of the inputs have to be spent in a transaction. That means that if we send part of the tokensLeft to some user, we have to send the rest to the tokenCreator to preserve that amount.