simulateTransaction

Submit a trial contract invocation to get back return values, expected ledger footprint, and expected costs.

Parameters

• <xdr.TransactionEnvelope> - The transaction to be simulated (serialized in base64)

Returns

• <object>
  • cost: <object> - Information about the fees expected, instructions used, etc.
    • cpuInsns: <string> - Stringified-number of the total cpu instructions consumed by this transaction
    • memBytes: <string> - Stringified-number of the total memory bytes allocated by this transaction
  • footprint: <xdr.LedgerFootprint> -Array of ledger keys expected to be written by this transaction. (serialized in base64)
  • results: <object[]> - If error is present then results will not be in the response
    • xdr: <xdr.ScVal> - (optional) Only present on success. xdr-encoded return value of the contract call
  • latestLedger: <string> - Stringified-number of the current latest ledger observed by the node when this response was generated.
  • error: <string> - (optional) only present if the transaction failed. This field will include more details from stellar-core about why the invoke host function call failed.

Examples

The example transaction below invokes the increment function from the increment example contract.

Request

{
  "jsonrpc": "2.0",
  "id": 8675309,
  "method": "simulateTransaction",
  "params": {
    "transaction": "AAAAAgAAAAAdq+kGxmBG/ikQNdYHQ2fBAG+8Av/xp1ZfPZ9Xt42ragAAJxAAAAAAAAAAAgAAAAEAAAAAAAAAAAAAAABjzuFcAAAAAAAAAAEAAAAAAAAAGAAAAAAAAAACAAAABAAAAAEAAAAGAAAAIBv6ziOnWcVRdGMZjtFKSWnLSndMp9JPVLLXxQqAvKqJAAAABQAAAAlpbmNyZW1lbnQAAAAAAAAAAAAAAAAAAAAAAAAA"
  }
}

Response

{
  "jsonrpc": "2.0",
  "id": 8675309,
  "result": {
    "results": [
      {
        "xdr": "AAAAAQAAAAY="
      }
    ],
    "footprint": "AAAAAgAAAAYb+s4jp1nFUXRjGY7RSklpy0p3TKfST1Sy18UKgLyqiQAAAAMAAAADAAAAB9QqWUc9AUjduz5qrbJgYb/gACScB4Jq7yTT6x0QJfZfAAAAAQAAAAYb+s4jp1nFUXRjGY7RSklpy0p3TKfST1Sy18UKgLyqiQAAAAUAAAAHQ09VTlRFUgA=",
    "cost": {
      "cpuInsns": "163642",
      "memBytes": "1506"
    },
    "latestLedger": "230473"
  }
}