How to make the login part in QuickFIX - c++

Question

How can I make the login part in QuickFIX in c++?
I found tons of tutorials and articles on how to do this on c# or java, but nothing on c++.
I have a server (acceptor), and a client (initiator). The username and password of the client are stored in the settings file, and are hardcoded in the server program.
From what I've read in the client I set the username and password in fromAdmin() and read and check the in the server in the toAdmin(), but how do I do that?
Here's what I've tried so far:
cast the message to a FIX44::Logon& object using:
FIX44::Logon& logon_message = dynamic_cast<FIX44::Logon&>(message);
Set the Username and password to the logon object like this:
if(session_settings.has("Username"))
{
FIX::Username username = session_settings.getString("Username");
logon_message.set(username);
}
And send the message like this:
FIX::Message messageToSend = logon_message;
FIX::Session::sendToTarget(messageToSend);
But I get this error on the cast:
cannot dynamic_cast 'message' (of type 'class FIX::Message') to type 'struct FIX44::Logon&' (target is not pointer or reference to complete type)
What I've tried I got inspired from http://niki.code-karma.com/2011/01/quickfix-logon-support-for-username-password/comment-page-1/.
I'm still not clear on how to make the client and the server.
Can anyone help me?

Answer 1

Possible mistakes:
I think you have fromAdmin()/toAdmin() backward. toAdmin() is called on outgoing admin messages, fromAdmin() is called on incoming. For the Initiator, you must set the fields within the toAdmin() callback. Your Acceptor will check the user/pass in fromAdmin().
Are you trying to dynamic_cast without first checking to see if it was a Logon message? The toAdmin() callback handles all admin messages; the message could be a Heartbeat, Logon, Logout, etc. That might explain your cast error.
As to what the code should look like, my C++ is rusty, but the basic pattern is this:
void YourMessageCracker::toAdmin( FIX::Message& message, const FIX::SessionID& sessionID)
{
if (FIX::MsgType_Logon == message.getHeader().getField(FIX::FIELD::MsgType))
{
FIX44::Logon& logon_message = dynamic_cast<FIX44::Logon&>(message);
logon_message.setField(FIX::Username("my_username"));
logon_message.setField(FIX::Password("my_password"));
}
}
From there, I think you can see how you'd write a similar fromAdmin() where you'd get the fields instead of setting them.
The above uses hard-coded user/pass, but you probably want to pull it from the config file. I think your calls to session_settings.getString(str) are correct for that.
(Please forgive any coding errors. I'm much more fluent in the Java/C# versions of the QF engine, though the basic principles are the same.)
I see that your first web reference uses the FIELD_GET_REF macro. It may be better than message.getHeader().getField(), but I'm not familiar with it.