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Delayed Messages for Program Automation

Smart contracts on other blockchains typically rely on external, centralized resources to continue functioning. This means that the code of these contracts will not run and make changes to the blockchain's state until it is triggered by an off-chain transaction.

The external transaction serves as a "poke" to activate the smart contract and initiate its logic. For instance, someone can start an auction by sending a message to the auction contract. When the auction time has passed, the contract will need to process the result of the auction. However, this will not happen until someone sends the appropriate message to the contract to trigger this action.

Gear Protocol solves this issue by introducing delayed messaging functionality. Programs in Vara Network can execute themselves an unlimited number of blocks, as long as enough gas for execution is kept available. The gas reservation option ensures this. As a result, the need for including centralized components in dApps is eliminated, allowing them to function totally on-chain.

The msg::send_delayed function allows sending a message after a specified delay. The function takes the following parameters:

  • program - the program (or user) to which the message will be sent
  • payload - the payload of the message
  • value - the amount of tokens to be sent with the message
  • delay - the delay in blocks after which the message will be sent

The delayed message will be executed after the specified delay measured in blocks. For example, on a network with a block production time of 3 seconds, a delay of 20 blocks is equal to 1 minute.

Gear Protocol enables the message processing to be paid with reserved gas by using the msg::send_delayed_from_reservation function, which takes a reservation ID as the first parameter.

Considering the auction example, the auction can be started by sending a message to the auction program. After completing all the necessary logic, the auction program will send a delayed message to itself, which will settle the auction after the indicated time.