SimulateTransactionRequest

public final class SimulateTransactionRequest : @unchecked Sendable

Request parameters for simulating a Soroban transaction.

SimulateTransactionRequest configures how a transaction should be simulated by the Soroban RPC server.

Parameters:

  • transaction: The transaction to simulate (must contain InvokeHostFunction operation)
  • resourceConfig: Optional resource budget configuration (default: 3000000 instruction leeway)
  • authMode: Authorization simulation mode (protocol 23+)
  • useUpgradedAuth: Request protocol-27 V2 credential arms in the simulation response (default true)

Authorization modes (protocol 23+):

  • “enforce”: Strict authorization checking (default)
  • “record”: Record auth entries without enforcing
  • “record_allow_nonroot”: Allow non-root authorization

useUpgradedAuth flag

The key "useUpgradedAuth" is always included as a sibling of "transaction" in the JSON-RPC params, carrying the current flag value. When true (the default), the RPC records ADDRESS_V2 credential arms; when false, legacy ADDRESS arms. Set the flag to false on a network below protocol 27, where V2 credential arms invalidate the transaction.

RPC servers that do not support useUpgradedAuth silently ignore the key and return legacy ADDRESS credential arms. The caller must detect V2 support by inspecting the credential arm of the returned entries, not by expecting an error.

Example:

let request = SimulateTransactionRequest(
    transaction: transaction,
    resourceConfig: ResourceConfig(instructionLeeway: 5000000)
)

let response = await server.simulateTransaction(simulateTxRequest: request)

See also:

  • [SorobanServer.simulateTransaction] for running simulations
  • [SimulateTransactionResponse] for simulation results
  • [ResourceConfig] for resource configuration
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  • Transaction to simulate (must contain InvokeHostFunction operation).

    Declaration

    Swift

    public let transaction: Transaction
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  • Resource limits for simulation (instruction leeway, memory bounds).

    Declaration

    Swift

    public let resourceConfig: ResourceConfig?
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  • Support for non-root authorization. Only available for protocol >= 23 Possible values: “enforce” | “record” | “record_allow_nonroot”

    Declaration

    Swift

    public let authMode: String?
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  • Selects the credential arm the simulation records.

    When true (the default), ADDRESS_V2 credential arms are requested; when false, legacy ADDRESS arms. The key is always sent in the JSON-RPC params with the current value. Set to false on a network below protocol 27, where V2 arms invalidate the transaction. RPC servers without support silently ignore this flag and return legacy ADDRESS entries.

    Declaration

    Swift

    public let useUpgradedAuth: Bool
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  • Creates a request for simulating Soroban transaction execution.

    Declaration

    Swift

    public init(transaction: Transaction, resourceConfig: ResourceConfig? = nil, authMode: String? = nil, useUpgradedAuth: Bool = true)
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  • Builds JSON-RPC request parameters from the simulation configuration.

    Declaration

    Swift

    public func buildRequestParams() -> [String : Any]
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