v0.50.3124

• New: While EventFlow tries to limit the about of painful API changes, the
  introduction of execution/command results are considered a necessary step
  towards as better API.

  Commands and command handlers have been updated to support execution
  results. Execution results is meant to be an alternative to throwing domain
  exceptions to do application flow. In short, before you were required to
  throw an exception if you wanted to abort execution and "return" a failure
  message.

  The introduction of execution results changes this, as it allows
  returning a failed result that is passed all the way back to the command
  publisher. Execution results are generic and can thus contain e.g. any
  validation results that a UI might need. The ICommandBus.PublishAsync
  signature has changed to reflect this.

  from

      Task<ISourceId> PublishAsync<TAggregate, TIdentity, TSourceIdentity>(
        ICommand<TAggregate, TIdentity, TSourceIdentity> command)
        where TAggregate : IAggregateRoot<TIdentity>
        where TIdentity : IIdentity
        where TSourceIdentity : ISourceId

  to

      Task<TExecutionResult> PublishAsync<TAggregate, TIdentity, TExecutionResult>(
        ICommand<TAggregate, TIdentity, TExecutionResult> command,
        CancellationToken cancellationToken)
        where TAggregate : IAggregateRoot<TIdentity>
        where TIdentity : IIdentity
        where TExecutionResult : IExecutionResult

  Command handler signature has changed from

      Task ExecuteAsync(
          TAggregate aggregate,
          TCommand command,
          CancellationToken cancellationToken);

  to

      Task<TExecutionResult> ExecuteCommandAsync(
          TAggregate aggregate,
          TCommand command,
          CancellationToken cancellationToken)

  Migrating to the new structure should be seamless if your current code base
  inherits its command handlers from the provided CommandHandler<,,> base
  class.

• Breaking: Source IDs on commands have been reworked to "make room" for
  execution results on commands. The generic parameter from ICommand<,,>
  and ICommandHandler<,,,> has been removed in favor of the new execution
  results. ICommand.SourceId is now of type ISourceId instead of using
  the generic type and the ICommandBus.PublishAsync no longer returns
  Task<ISourceId>

  To get code that behaves similar to the previous version, simply take the
  ISourceId from the command, i.e., instead of this

  var sourceId = await commandBus.PublishAsync(command);

  write this

  await commandBus.PublishAsync(command);
  var sourceId = command.SourceId;

  (CancellationToken and .ConfigureAwait(false) omitted fromt he above)

• Breaking: Upgraded NuGet dependency on RabbitMQ.Client from >= 4.1.3
  to >= 5.0.1