public IMutating MutateIncoming(IMutating command)
{
CurrentMessage = command.Message;
// There are certain headers that we can make note of
// These will be committed to the event stream and included in all .Reply or .Publish done via this Unit Of Work
// Meaning all receivers of events from the command will get information about the command's message, if they care
foreach (var header in Defaults.CarryOverHeaders)
{
var defaultHeader = "";
command.Headers.TryGetValue(header, out defaultHeader);
if (string.IsNullOrEmpty(defaultHeader))
{
defaultHeader = NotFound;
}
var workHeader = $"{Defaults.PrefixHeader}.{header}";
CurrentHeaders[workHeader] = defaultHeader;
}
CurrentHeaders[$"{Defaults.PrefixHeader}.OriginatingType"] = CurrentMessage.GetType().FullName;
// Copy any application headers the user might have included
var userHeaders = command.Headers.Keys.Where(h =>
!h.Equals("CorrId", StringComparison.InvariantCultureIgnoreCase) &&
!h.Equals("WinIdName", StringComparison.InvariantCultureIgnoreCase) &&
!h.StartsWith("NServiceBus", StringComparison.InvariantCultureIgnoreCase) &&
!h.StartsWith("$", StringComparison.InvariantCultureIgnoreCase) &&
!h.Equals(CommitHeader) &&
!h.Equals(Defaults.CommitIdHeader, StringComparison.InvariantCultureIgnoreCase) &&
!h.Equals(Defaults.RequestResponse, StringComparison.InvariantCultureIgnoreCase) &&
!h.Equals(Defaults.Retries, StringComparison.InvariantCultureIgnoreCase) &&
!h.Equals(Defaults.EventHeader, StringComparison.InvariantCultureIgnoreCase));
foreach (var header in userHeaders)
{
CurrentHeaders[header] = command.Headers[header];
}
CurrentHeaders[Defaults.InstanceHeader] = Defaults.Instance.ToString();
if (command.Headers.ContainsKey(Headers.CorrelationId))
{
CurrentHeaders[Headers.CorrelationId] = command.Headers[Headers.CorrelationId];
}
CommitId = Guid.NewGuid();
try
{
string messageId;
// Attempt to get MessageId from NServicebus headers
// If we maintain a good CommitId convention it should solve the message idempotentcy issue (assuming the storage they choose supports it)
if (CurrentHeaders.TryGetValue(Defaults.MessageIdHeader, out messageId))
{
CommitId = Guid.Parse(messageId);
}
// Allow the user to send a CommitId along with his message if he wants
if (CurrentHeaders.TryGetValue(Defaults.CommitIdHeader, out messageId))
{
CommitId = Guid.Parse(messageId);
}
}
catch (FormatException) { }
// Helpful log and gets CommitId into the dictionary
var firstEventId = UnitOfWork.NextEventId(CommitId);
Logger.Debug($"Starting unit of work - first event id {firstEventId}");
return(command);
}
