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Fungible Tokens

Introduction - Fungible vs Non-Fungible Tokens​

  • Fungibility refers to an asset's ability to be exchanged for something else of equal value;
  • Some examples of fungible assets include currencies, commodities, and precious stones;
  • Non-fungible assets are unique, requiring much more complex valuation before a sale and include things like real estate, art, and sports cards.

Throughout the lab, you will need to convert values from decimals to hex to ascii, etc. Use this tool to make your job easier.

Practice​

Think about the following example if fungible or non-fungible:

  • Diamond rock;
  • Penthouse apartment in Manhattan;
  • Mona Lisa painting;
  • LeBron James sport card;
  • LeBron James shirt he played in the 2020 NBA Finals;
  • A character in World of Warcraft.

Issuance of fungible ESDT tokens​

ESDT tokens are issued via a request to the Metachain, which is a transaction submitted by the Account which will manage the tokens. When issuing a token, one must provide a token name, a ticker, the initial supply, the number of decimals for display purpose and optionally additional properties. The issuance cost is set to 0.05 EGLD.

The receiver address erd1qqqqqqqqqqqqqqqpqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqzllls8a5w6u is a built-in system smart contract (not a VM-executable contract), which only handles token issuance and other token management operations, and does not handle any transfers. The contract will add a random string to the ticker thus creating the token identifier. The random string starts with “-” and has 6 more random characters (3 bytes - 6 characters hex encoded). For example, a token identifier could look like ALC-6258d2.

Read more about issuance of fungible ESDT tokens here.

Issuance example:​

IssuanceTransaction {
    Sender: <account address of the token manager>
    Receiver: erd1qqqqqqqqqqqqqqqpqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqzllls8a5w6u
    Value: 50000000000000000 # (0.05 EGLD)
    GasLimit: 60000000
    Data: "issue" +
          "@" + <token name in hexadecimal encoding> +
          "@" + <token ticker in hexadecimal encoding> +
          "@" + <initial supply in hexadecimal encoding> +
          "@" + <number of decimals in hexadecimal encoding>
}

Practice​

  • Issue a token of your own. Choose whatever name and ticker you want. Check the existance of your token via Testnet Explorer.

Mint fungible ESDT tokens​

NOTE

Actions issue and mint are distinct! First, one must issue the token to exist on the blockchain. Second, the owner/issuer of the token must mint tokens.

The transaction to mint tokens is:

LocalMintTransaction {
    Sender: <address with ESDTRoleLocalMint role>
    Receiver: <same as sender>
    Value: 0
    GasLimit: 300000
    Data: "ESDTLocalMint" +
          "@" + <token identifier in hexadecimal encoding> +
          "@" + <supply to mint in hexadecimal encoding>
}

Note that the sender and the receiver are the same address, which is the creator of the token. After this transaction, he will receive in his wallet the minted tokens.

Practice​

  • Use the token created at the previous section to mint some tokens. Verifiy on the Testnet Explorer and in your wallet.

Setting ESDT Roles​

Notice the Properties section in a Token page. UTK tokens

There are several roles assigned to a token. To change those roles we need to make a blockchain transaction:

RolesAssigningTransaction {
    Sender: <address of the ESDT manager>
    Receiver: erd1qqqqqqqqqqqqqqqpqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqzllls8a5w6u
    Value: 0
    GasLimit: 60000000
    Data: "setSpecialRole" +
          "@" + <token identifier in hexadecimal encoding> +
          "@" + <address to assign the role(s) in a hexadecimal encoding> +
          "@" + <role in hexadecimal encoding> +
          "@" + <role in hexadecimal encoding> +
          ...
}

Practice​

  • Observe the roles of your newly created token.
  • Add ESDTRoleLocalMint and ESDTRoleLocalBurn for your address.
  • Mint 1000 tokens.

You can read more about roles in the documentation.

Burning ESDT Tokens​

Anyone that holds an amount of ESDT tokens may burn it at their discretion, effectively losing them permanently. This operation reduces the total supply of tokens, and cannot be undone, unless the token manager mints more tokens.

Do you have roles for burning?

LocalBurnTransaction {
    Sender: <address with ESDTRoleLocalBurn role>
    Receiver: <same as sender>
    Value: 0
    GasLimit: 300000
    Data: "ESDTLocalBurn" +
          "@" + <token identifier in hexadecimal encoding> +
          "@" + <supply to burn in hexadecimal encoding>
}

Practice​

  • Burn 500 tokens

Other actions for ESDTTokens​

Pausing and Unpausing​

The manager of an ESDT token may choose to suspend all transactions of the token, except minting, freezing/unfreezing and wiping. Check more details here.

Freezing and Unfreezing​

The manager of an ESDT token may freeze the tokens held by a specific Account. As a consequence, no tokens may be transferred to or from the frozen Account. Freezing and unfreezing the tokens of an Account are operations designed to help token managers to comply with regulations. The manager of an ESDT token may choose to suspend all transactions of the token, except minting, freezing/unfreezing and wiping. Check more details here.

Wiping​

The manager of an ESDT token may wipe out all the tokens held by a frozen Account. This operation is similar to burning the tokens, but the Account must have been frozen beforehand, and it must be done by the token manager. Wiping the tokens of an Account is an operation designed to help token managers to comply with regulations. The manager of an ESDT token may choose to suspend all transactions of the token, except minting, freezing/unfreezing and wiping. Check more details here.