The Indexer (Envio)

Instead of the LICEN Orchestrator constantly querying the blockchain for new events, we use Envio HyperIndex to build a real-time, queryable GraphQL API.

Why an Indexer?

Scanning the blockchain block-by-block is slow and computationally expensive. Envio processes blocks instantly and stores our custom DataPolicy events in a PostgreSQL database, exposing them via GraphQL.

Configuration

The indexer is configured in two main files located in packages/indexer/:

1. config.yaml: Defines the network (0G Testnet), the smart contract address, and the specific events to listen for (e.g., AccessGranted).
2. schema.graphql: Defines the database schema. Every time an event is detected, it is mapped to an entity defined here.

Event Handlers

The logic that maps raw blockchain events to GraphQL entities is written in TypeScript in packages/indexer/src/EventHandlers.ts.

When an AccessGranted event is detected, the handler creates a new Job entity with a status of Granted.

The GraphQL API

The Orchestrator polls the Envio GraphQL API using a simple query to find pending jobs:

query GrantedJobs {
  Job(where: { state: { _eq: "Granted" } }) {
    id
    datasetRoot
    requestedEpochs
  }
}

Hosting

During local development, you can run the indexer using Docker (pnpm dev inside the indexer folder).

For production, the indexer is deployed to the Envio Hosted Service, providing a reliable, always-on GraphQL endpoint for the Orchestrator to query.