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11. Use cardano-api

· 2 min read




  • To implement Hydra Head's ledger we have been working with the ledger-specs packages which provide a low-level interface to work with transactions and ledgers
    • We also use a lightly wrapped ledger-specs API as our interface for Off-chain transaction submission. This introduced some boilerplate in order to align with cardano-api and provide JSON serialisation.
  • In our initial experiments connecting directly to a cardano node we have also been using the ledger API for building transactions for want of some scripts-related features in the cardano-api
  • cardano-api is expected to be the supported entrypoint for clients to interact with Cardano chain while ledger-specs is reserved for internal use and direct interactions with ledgers
  • cardano-api now provides all the features we need to run our on-chain validators



  • Use cardano-api types and functions instead of ledger-specs in Hydra.Chain.Direct component
  • Use cardano-api types instead of custom ones in Hydra.Ledger.Cardano component


  • Removes the boilerplate in Hydra.Ledger.Cardano required to map cardano-api types sent by clients to builtin and ledger-specs types
  • Simplifies the Hydra.Chain.Direct component:
    • Replaces custom transaction building in Tx
    • Replaces custom transaction fees calculation and balancing in Wallet
    • Replace low-level connection establishment using cardano-api functions connecting to the node (keeping the chain sync subscription)