The JSON RPC module implements the JSON RPC API layer, something that dApp developers use to interact with the blockchain.
It includes support for standard json-rpc endpoints, as well as websocket endpoints.
The Polygon SDK uses the blockchain interface to define all the methods that the JSON RPC module needs to use, in order to deliver its endpoints.
The blockchain interface is implemented by the Minimal server. It is the base implementation that's passed into the JSON RPC layer.
All the standard JSON RPC endpoints are implemented in:
The Filter Manager is a service that runs alongside the JSON RPC server.
It provides support for filtering blocks on the blockchain.
Specifically, it includes both a log and a block level filter.
The Filter Manager relies heavily on Subscription Events, mentioned in the Blockchain section
Filter Manager events get dispatched in the Run method: