Re: [Quickfix-developers] Does QuickFix implement Message Queue mechanism to make sure all messages are delivered ?

[Joerg T. <Joe...@ma...>]

Hi Frank,

> I'm trying to make use of quickfix to replace the old fix gateway(ugly 
> code, not flexible, only support fix4.0) in my company.

Good to hear that. That is the idea behind QuickFIX: Joining efforts to 
get one, high quality solution.

> I have many years of socket programming experience. Every time when I 
> write a tcp socket program, I'll worry about buffering of read and write 
> stream, queueing of messages ready to send, queueing of messages 
> received and waiting for handling. If I add such kinds of handling in 
> the socket program, the program will be really very stable and robust; 
> if not, errors will occur after it runs for some time.

Actually, the FIX protocol itself is independent of the underlying 
transport, it would also work with UDP. The session level protocol takes 
care of lost and out-of-order messages, so if an implementation fully 
implements the session level protocol of FIX (which QF does), you should 
not worry about this.

> My question is: Does QuickFix have such kinds of handling ? especially 
> message queue mechanism ?  May I borrow it to deal with other sockets 
> (My program is a fix gateway, one side connects trading system (not fix 
> protocol), one side connects ECN(fix protocol)) ?

For the incoming data, there is now queue/buffer besides the TCP buffer, 
so that every message read is immediately forwarded to the fromApp() or 
fromAdmin() callback. So it is the responsibility of the application to 
queue these message if needed.

The outgoing data is saved in a messsage store (file, database, your own 
implementation). You can send data to a session as soon as it is created 
(onCreate() callback triggered). This is independent of the logon state 
of the session, i.e. you can send messages to a session if it is logged 
off. If the session gets logged on again, these messages are 
transferred. The reason behind that is the requirement of the FIX 
protocol to be always able to resend messages.

If this does not answer your question, please do not hesitate to ask.

BTW, do you have some new exchange/ECN to be added to our WikiFIX?

Cheers, Jörg

-- 
Joerg Thoennes
                                http://macd.com
Tel.: +49 (0)241 44597-24      Macdonald Associates GmbH
Fax : +49 (0)241 44597-10      Lothringer Str. 52, D-52070 Aachen