[Quickfix-developers] PossDupFlag

[Rainer S. <ra...@aa...>]

Hi all,

I have run into some confusion regarding the PossDupFlag:

The release notes for quickfix 1.1.0 say the application programmer is 
responsible for handling messages with the PossDupFlag set.

I don't really understand the motivation for this. Isn't quickfix 
responsible for handling the session level stuff, including guaranteed 
delivery of messages in the correct order?

If I simply ignore the PossDupFlag in my fromApp method, does this mean 
I can get the same message twice?

If I check for the PossDupFlag in fromApp, what is the "right thing" to 
do with a message with PossDupFlag=Y?

Also confusing:

In the tradeclient example, there exists the following code in the toApp 
method:

   try
   {
     FIX::PossDupFlag possDupFlag;
     message.getHeader().getField(possDupFlag);
     if(possDupFlag) throw FIX::DoNotSend();
   } catch(FIX::FieldNotFound&) {}

This code prevents all application level messages with PossDupFlag=Y 
from being sent, right? Again, what is the motivation for this? Doesn't 
this defeat the purpose of FIX (guaranteed delivery of messages)?

Thanks!

Rainer Staringer
AAA+ Software