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Introduction

As mentioned earlier, Qubic smart contracts run directly on bare metal—no virtual machine involved. But how does it actually work? Let’s explore.

How It Works​

In Qubic, a smart contract is simply a C++ class with methods. The state of your contract is stored in the members of its nested StateData struct, accessed via state.get() (read) and state.mut() (write).

Functions and Procedures​

  • Procedure: If a method modifies the state (via state.mut()), it’s called a Procedure.
  • Function: If a method only reads the state (via state.get()) without modifying it, it’s called a Function.

Interacting with Smart Contracts in Qubic​

  • Function: Invoked via TCP messages. You send a message to a node requesting it to call a specific function, and the node immediately returns the response.
  • Procedure: Invoked via transactions. Since it modifies the contract state, all nodes must execute it and update the state. The transaction specifies the contract address, the procedure to call, and its parameters.