CsvExportMessageHandler.cs

public class CsvExportMessageHandler : IHandleMessages<BeginCsvExportMessage>
{
    public IExportFileCreator FileCreator { get; set; }
    public IExportFormatter Formatter { get; set; }
    public IBus Bus { get; set; }
    public ILog Log { get; set; }

    public void Handle(BeginCsvExportMessage message)
    {
        Log.Info("Performing CSV Export on: " + message.Assessment.AssessmentReportGuid);

        var path = FileCreator.CreateExportFile(message.Assessment.AssessmentReportGuid);
        using (var writer = new StreamWriter(path))
        using (var csv = new CsvWriter(writer))
        {
            Formatter.Export(message.Assessment.AssessmentReportGuid, csv);
        }
            
        var reply = message.CreateReply();
        reply.ExportFileLocation = path;
        Bus.Reply(reply);
    }
}