BlockchainProcessingCustomOrchestrator.cs

//Example of creating a simple custom blockchain crawler orchestrator that stops the crawling at transaction receipt.
//This is done as crawling currently does not disable steps before getting the data.

using Nethereum.BlockchainProcessing.Processor;
using Nethereum.BlockchainProcessing.BlockProcessing;
using Nethereum.BlockchainProcessing.BlockProcessing.CrawlerSteps;
using Nethereum.RPC.Eth.DTOs;
using Nethereum.Web3;
using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using Nethereum.Contracts.Services;
using Nethereum.BlockchainProcessing.ProgressRepositories;
using Nethereum.BlockchainProcessing;
using Nethereum.RPC.Eth.Blocks;

public class BlockProcessing_CustomOrchestrator {
  /// <summary>
  /// Demonstrates how to create a custom orchestrator
  /// </summary>
  public static async Task Main(string[] args) {
    var blocks = new List < BlockWithTransactions > ();

    var web3 = new Web3("https://rinkeby.infura.io/v3/7238211010344719ad14a89db874158c");

    //if we need to stop the processor mid execution - call cancel on the token
    var cancellationTokenSource = new CancellationTokenSource();

    var blockProcessingSteps = new BlockProcessingSteps();
    blockProcessingSteps.BlockStep.AddSynchronousProcessorHandler(b => {
      blocks.Add(b);
      cancellationTokenSource.Cancel();
    });

    //create our orchestrator
    var orchestrator = new SimpleBlockCrawlOrchestrator(web3.Eth, blockProcessingSteps);

    // create progress repository
    var progressRepository = new InMemoryBlockchainProgressRepository();

    // last confirmation strategy / service (using web3.Eth.Blocks.GetBlockNumber) 
    var lastConfirmedBlockNumberService = new LastConfirmedBlockNumberService(web3.Eth.Blocks.GetBlockNumber, 12);

    var processor = new BlockchainProcessor(orchestrator, progressRepository, lastConfirmedBlockNumberService);
    //crawl the required block range
    await processor.ExecuteAsync(
      cancellationToken: cancellationTokenSource.Token, 2830144);

    Console.WriteLine($"Expected 1 block, actual block count: {blocks.Count}");
  }

  public class SimpleBlockCrawlOrchestrator: BlockCrawlOrchestrator {
    public SimpleBlockCrawlOrchestrator(IEthApiContractService ethApi, BlockProcessingSteps blockProcessingSteps): base(ethApi, blockProcessingSteps) {

    }

    protected override async Task CrawlTransactionReceipt(CrawlerStepCompleted < TransactionVO > completedStep) {
      //Stopping processing on CrawlingTransactionReceipt and out putting the input
      Console.WriteLine(completedStep.StepData.Transaction.Input);
    }
  }
}