Module frame_system::offchain

Module helpers for off-chain calls.

Overview

This module provides transaction related helpers to:

• Submit a raw unsigned transaction
• Submit an unsigned transaction with a signed payload
• Submit a signed transaction.

Usage

Please refer to example-offchain-worker for a concrete example usage of this crate.

Submit a raw unsigned transaction

To submit a raw unsigned transaction, SubmitTransaction can be used.

Signing transactions

To be able to use signing, the following trait should be implemented:

• AppCrypto: where an application-specific key is defined and can be used by this module’s helpers for signing.
• CreateSignedTransaction: where the manner in which the transaction is constructed is defined.

Submit an unsigned transaction with a signed payload

Initially, a payload instance that implements the SignedPayload trait should be defined. See PricePayload

The payload type that is defined defined can then be signed and submitted onchain.

Submit a signed transaction

Signer can be used to sign/verify payloads

Structs

• Account
  Details of an account for which a private key is contained in the keystore.
• ForAll
  Marker struct used to flag using all supported keys to sign a payload.
• ForAny
  Marker struct used to flag using any of the supported keys to sign a payload.
• Signer
  Provides an implementation for signing transaction payloads.
• SubmitTransaction
  Provides the ability to directly submit signed and unsigned transaction onchain.

Traits

• AppCrypto
  A type binding runtime-level Public/Signature pair with crypto wrapped by RuntimeAppPublic.
• CreateInherent
  Interface for creating an inherent.
• CreateSignedTransaction
  Interface for creating an old-school signed transaction.
• CreateTransaction
  Interface for creating a transaction.
• CreateTransactionBase
  Common interface for the CreateTransaction trait family to unify the Call type.
• SendSignedTransaction
  Submit a signed transaction to the transaction pool.
• SendUnsignedTransaction
  Submit an unsigned transaction onchain with a signed payload
• SignMessage
  A message signer.
• SignedPayload
  Utility trait to be implemented on payloads that can be signed.
• SigningTypes
  A wrapper around the types which are used for signing.