class ExampleSystem : BaseGameJobSystem<TJob> 
{
  // Or you can provide operations service that has been created in DI container
  public override INativeOperationsService ProvideNativeOperationsService()
    => new NativeOperationsService();

  public override int GetChunkSize(EcsSystems systems)
    => 10;

  public override EcsFilter GetFilter(EcsWorld world) 
  {
    return world.Filter<Component1>().Inc<Component2>().End();
  }

  // Here you should set entities pool
  public override void SetData(EcsSystems systems, ref TJob job) 
  {
    var world = systems.GetWorld();
    var filter = GetFilter()
    
    job.Filter = GetFilterWrapper(filter);

    job.Component1Operations = OperationsService
      .GetReadOnlyOperations<Component1>(systems);

    job.Component2Operations = OperationsService
      .GetReadOnlyOperations<Component2>(systems); 

    job.Component3Operations = OperationsService
      .GetReadWriteOperations<Component3>(systems);
  }
}

struct Component1
{
  int a;
}

struct Component2 
{
  int b;
}

struct Component3 
{
  int c;
}

[BurstCompile]
public struct SummAndWriteJob : IJobParallelFor
{
  public NativeFilterWrapper Filter;

  public ReadOnlyNativeEntityOperations<Component1> Component1Operations;
  public ReadWriteNativeEntityOperations<Component2> Component2Operations;
  public ReadWriteNativeEntityOperations<Component3> Component3Operations;

  public void Execute(int index) 
  {
    var entity = Filter.Entity(index);

    var component1Value = Component1Operations.Get(entity);
    var component2Value = Component2Operations.Get(entity);

    ref var component3Value = ref Component3Operations.Add(entity);

    component3Value = component1Value + component2Value;

    Component2Operations.Del(entity);
  }
}