Processor Basic

The core concept of a Sentio project is Processor. A processor is usually a typescript project that contains logic to use blockchain data to generate user-defined data to sentio. The processor should be written using Sentio's SDK framework and be submitted and run on Sentio.

While Sentio processor provides max performance and flexibility, we also support hosted-subgraph that still have lots of feature like SQL/GraphQL API, analytic dashboard, multi-versioning. So that you could easily run data pipeline on Sentio without writing new code.

A Sentio processor could handle multiple contracts on multiple chains. To import a contract, simple copy the contract's ABI JSON file into abis directory. Run sentio build or sentio gen will generate contract processor files into the src/types directory.

Then you can use the generated contract processor class to bind to an address, and add different handlers, the SDK also comes up with several built-in contract processors, a minimal processor example with built-in ERC20 processor is:

import { ERC20Processor } from '@sentio/sdk/eth/builtin/erc20'

ERC20Processor.bind({ address: '0x1e4ede388cbc9f4b5c79681b7f94d36a11abebc9', network: EthChainId.ETHEREUM })
  .onEventTransfer((event, ctx) => {
    ctx.meter.Counter('token').add(event.args.value)
  }
)

The above code first bind ERC20 contract processor to a specific address on the ethereum mainnet (specify with network=CHAIN_IDS.ETHEREUM, can be omitted if just using Ethereum mainnet). Then it registers a function that handles Transfer event, for each of these events, we add the transfer value to a metric named token.

If you bring your own ABI, our codegen will automatically generate all event handler registration method in a typesafe way as well.