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Watchers

tip

Start by reading the Architecture section if you haven't already.

Watchers are off-chain operators that monitor blockchain activity and host the App-Gateway, a contract that enables custom off-chain logic. They execute logic defined by application developers and generate a proof, which is then passed to a Transmitter for onchain verification by a Switchboard.

Watchers act as a bridge between the user and the blockchain, enabling developers to insert useful off-chain logic before onchain smart contracts are executed.

watcher diagram

Today, when users interact with your application, they typically do so directly onchain, facing issues like high gas fees, complex bridging, and multi-chain interactions. Watchers help streamline this process by handling some of the logic off-chain, improving performance and user experience.

Key Role of Watchers​

  • Hosts App-Gateways: Watchers run specialized virtual machines (VMs) that host App-Gateway contracts, which execute custom off-chain logic defined by application developers.

  • Generate Proofs: Watchers observe blockchain events, execute logic, and generate proofs that are later verified onchain by Switchboards.

  • Passive Role: Anyone can become a Watcher by running a node. There are no special permissions required to participate.

Read more about the relationship between Watchers and Switchboards here.

How Watchers Fit into the Protocol​

  1. User signs an off-chain message and sends it to a Watcher where the App-Gateway logic is executed.
  2. The Watcher generates a proof, which is passed to a Transmitter.
  3. The Transmitter submits the proof onchain, where it is verified by a Switchboard before triggering the onchain smart contract.

Watchers are a critical component of the SOCKET protocol, providing flexibility to developers to introduce custom logic that can improve security, reduce costs, and enhance user experience.