Customize

If you are looking for how to configure EventFlow, look at the configuration documentation.

Whenever EventFlow doesn’t meet your needs, e.g. if you want to collect statistics on each command execution time, you can customize EventFlow.

Basically EventFlow relies on an IoC container to allow developers to customize the different parts of EventFlow.

Note: Read the section “Changing IoC container” for details on how to change the IoC container used if you have specific needs like e.g. integrating EventFlow into an Owin application.

You have two options for when you want to customize EventFlow

• Decorate an implementation
• Replace an implementation

Decorating implementations

In the case of collecting statistics, you might want to wrap the existing ICommandBus with a decorator class that can collect statistics on command execution times.

void ConfigureEventFlow()
{
  var resolver = EventFlowOptions.new
    .RegisterServices(DecorateCommandBus)
    ...
    .CreateResolver();
}

void DecorateCommandBus(IServiceRegistration sr)
{
  sr.Decorate<ICommandBus>((r, cb) => new StatsCommandBus(cb));
}

class StatsCommandBus : ICommandBus
{
  private readonly ICommandBus _internalCommandBus;

  public StatsCommandBus(ICommandBus commandBus)
  {
    _internalCommandBus = commandBus;
  }

  // Here follow implementations of ICommandBus that call the
  // internal command bus and logs statistics
  ...
}

Registering new implementations

The more drastic step is to completely replace an implementation. For this you use the Register(...) and related methods on IServiceRegistration instead of the Decorate(...) method.