Plutus Application Backend

Pre-requisites

Install Plutus Application Backend.
In order to be able to balance Plutus transaction we need funds on the wallet. In case of Testnet we can request tADA from the faucet.

Overview

This guide is to show how to invoke Plutus contracts with cardano-wallet.

Workflow

Once you have created a smart contract with PAB you can execute it via cardano-wallet.

There are three endpoints that need to be invoked to follow the workflow:

POST /wallets/{walletId}/transactions-balance - for balancing transaction from PAB.
POST /wallets/{walletId}/transactions-sign - for signing transaction.
POST /wallets/{walletId}/transactions-submit - for submitting transaction to the network.

Plutus Application Backend provides a payload of an unbalanced transaction. This transaction needs to be balanced with wallet's inputs such that it can be submitted to the network. The response from this endpoint returns fee and coin_selection of the balanced transaction as well as CBOR-encoded transaction represented in base64 encoding. We will need the returned transaction value to pass on to POST /wallets/{walletId}/transactions-sign endpoint.

> curl -X POST http://localhost:8090/v2/wallets/1b0aa24994b4181e79116c131510f2abf6cdaa4f/transactions-balance \
-d '{"transaction":"84a500800d80018183581d704d72cf569a339a18a7d9302313983f56e0d96cd45bdcb1d6512dca6a1a001e84805820923918e403bf43c34b4ef6b48eb2ee04babed17320d8d1b9ff9ad086e86f44ec02000e80a10481d87980f5f6","redeemers":[],"inputs":[]}' \
-H "Content-Type: application/json" | jq .transaction

hKYAgYJYIJs6ATvbNwo5xpOkjHfUzr9Cv4zuFLFicFwWwpPC4ltBAw2AAYKDWB1wTXLPVpozmhin2TAjE5g/VuDZbNRb3LHWUS3KahoAHoSAWCCSORjkA79Dw0tO9rSOsu4Eur7RcyDY0bn/mtCG6G9E7IJYOQDsKgV69YfvMZdbfIT11OqtWL9bv7n++Jx0f+TDFwodcRLCv14tOV5BoBhV6ODYaS1MNdWnvKCjgBq2bfNOAhoAApgxDoALWCAvUOolRvjOAgykW/zyq+sC/xivIoNGb4iK5IkYSz0tOaEEgdh5gPX2

Sign transaction

Once the transaction is balanced we need to sign it using our wallet's secure passphrase and pass the previously returned CBOR-encoded transaction . The sign endpoint will again return CBOR-encoded transaction which is needed to be passed further to POST /wallets/{walletId}/transactions-submit endpoint.

> curl -X POST http://localhost:8090/v2/wallets/1b0aa24994b4181e79116c131510f2abf6cdaa4f/transactions-sign \
-d '{"passphrase":"Secure Passphrase",
"transaction":"hKYAgYJYIJs6ATvbNwo5xpOkjHfUzr9Cv4zuFLFicFwWwpPC4ltBAw2AAYKDWB1wTXLPVpozmhin2TAjE5g/VuDZbNRb3LHWUS3KahoAHoSAWCCSORjkA79Dw0tO9rSOsu4Eur7RcyDY0bn/mtCG6G9E7IJYOQDsKgV69YfvMZdbfIT11OqtWL9bv7n++Jx0f+TDFwodcRLCv14tOV5BoBhV6ODYaS1MNdWnvKCjgBq2bfNOAhoAApgxDoALWCAvUOolRvjOAgykW/zyq+sC/xivIoNGb4iK5IkYSz0tOaEEgdh5gPX2"}' \
-H "Content-Type: application/json" | jq .transaction

hKYAgYJYIJs6ATvbNwo5xpOkjHfUzr9Cv4zuFLFicFwWwpPC4ltBAw2AAYKDWB1wTXLPVpozmhin2TAjE5g/VuDZbNRb3LHWUS3KahoAHoSAWCCSORjkA79Dw0tO9rSOsu4Eur7RcyDY0bn/mtCG6G9E7IJYOQDsKgV69YfvMZdbfIT11OqtWL9bv7n++Jx0f+TDFwodcRLCv14tOV5BoBhV6ODYaS1MNdWnvKCjgBq2bfNOAhoAApgxDoALWCAvUOolRvjOAgykW/zyq+sC/xivIoNGb4iK5IkYSz0tOaIAgYJYIAVUtVUzi4FodRYiBmO9mD5hQGo2YjjYDoCgw5gn+/w9WEAyVhMWNiK88QKW6HBXIVxQyu0E+9epkIQbCQwNjKur5ORLojHxIZtZDDfkT6caz0yxp92t4Y7rDwsDw4geMOkJBIHYeYD19g==

Submit transaction

We have our balanced and signed CBOR-encoded transaction represented in base64 encoding. Now we can submit it to the network with POST /wallets/{walletId}/transactions-submit endpoint.

> curl -X POST http://localhost:8090/v2/wallets/1b0aa24994b4181e79116c131510f2abf6cdaa4f/transactions-submit \
-d '{"transaction":"hKYAgYJYIJs6ATvbNwo5xpOkjHfUzr9Cv4zuFLFicFwWwpPC4ltBAw2AAYKDWB1wTXLPVpozmhin2TAjE5g/VuDZbNRb3LHWUS3KahoAHoSAWCCSORjkA79Dw0tO9rSOsu4Eur7RcyDY0bn/mtCG6G9E7IJYOQDsKgV69YfvMZdbfIT11OqtWL9bv7n++Jx0f+TDFwodcRLCv14tOV5BoBhV6ODYaS1MNdWnvKCjgBq2bfNOAhoAApgxDoALWCAvUOolRvjOAgykW/zyq+sC/xivIoNGb4iK5IkYSz0tOaIAgYJYIAVUtVUzi4FodRYiBmO9mD5hQGo2YjjYDoCgw5gn+/w9WEAyVhMWNiK88QKW6HBXIVxQyu0E+9epkIQbCQwNjKur5ORLojHxIZtZDDfkT6caz0yxp92t4Y7rDwsDw4geMOkJBIHYeYD19g=="}' \
-H "Content-Type: application/json"

{"id":"c287cd5a752ff632e07747109193ed8f8b8e446211563951e7f8e470ed859782"}

We can monitor status of the submitted transaction using GET /wallets/{walletId}/transactions/{transactionId} endpoint.

> curl -X GET http://localhost:8090/v2/wallets/1b0aa24994b4181e79116c131510f2abf6cdaa4f/transactions/c287cd5a752ff632e07747109193ed8f8b8e446211563951e7f8e470ed859782 | jq

{
  "status": "in_ledger",
...
"amount": {
  "quantity": 2170033,
  "unit": "lovelace"
},
"inserted_at": {
  "height": {
    "quantity": 3324947,
    "unit": "block"
  },
  "epoch_number": 187,
  "time": "2022-02-16T11:22:12Z",
  "absolute_slot_number": 50641316,
  "slot_number": 226916
},
...

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