Writing an Auction Smart Contract

Using PyTeal and Beaker

Footer sample to go here

May 4, 2022

English Auction

​

• Start auction
• Define asset being auctioned
• Define amount being auctioned
• Define starting price
• Define end time

​

• Bid
• Place bid
• Return previous bid

​

• End
• Give winner the asset
• Giver auctioneer the highest bid

​

2

Algorand L1 Features

​

• Fees
• 0.001 ALGO per transaction
• Only increases during congestion

​

• Minimum Balance Requirement
• Accounts must have at least 0.1 ALGO
• Increases per app/asset created/opted in

​

• Atomic Transactions
• 16 transactions can be grouped together
• Smart contract can read transactions in group
• Can pool fees

3

Algorand Asset Features

​

• Algorand Standard Asset (ASA)
• Tokens are native, not smart contracts

​

• Opt In
• Allow ledger to track asset balance for given account
• Increase MBR by 0.1 ALGO
• Asset transfer fails if receiver is not opted in

4

Algorand Smart Contract Features

​

• Contract Account
• A account in the ledger associated with contract
• Only contract logic can spend from account

​

• Storage
• Global storage: key/value pairs in contract

​

• Resource Access
• Must pre-defined touched assets, apps, and accounts

​

• ABI: Application Binary Interface (ARC-0004)
• Standard for method definition
• Standard for type encoding/decoding

5

Auction Smart Contract

​

• Start auction
• Save parameters in global storage
• Fund contract to meet MBR
• Opt contract into asset
• Send asset to contract in atomic transaction

​

• Bid
• Send bid in atomic transaction
• Return previous bid with inner transaction

​

• End
• Attempt to transfer asset to winner with inner transaction
• Send ALGO to auction creator with inner transaction

​

6

The Code

https://github.com/algorand-devrel/beaker-auction

7