[Quickfix-developers] Problem with Session::send (const std::string& string)

[Wjack07 <ck...@gm...>]

Hi: 

I am trying to trim the latency of sending message by using as less overhead
as possible.

But I met some weird issue, and have no clue so far. Hope anyone has some
idea.


Basically, instead of using FIX::Session::sendtotarget ( Message& message)

One can use  FIX::Session::send ( Message& message)*

*But the SessionID needs to be set up first. this can be done separately.
But once it is done, we can save this step for every to-be-sent message
after (in QuickFIX, it check the sesseionID every time when a message is to
be sent, and this slows down a little bit.) 


Furthermore, one can even use FIX::Session::sendRaw (Message& message)**
And this can further save few steps

**sendRaw in session.h is in "private" category, so the .h file needs to be
modified a bit before using.


To push further, I tried FIX::Session::send ( const std::string& string )***

*** again, it is in "private category" so the .h file needs to be modified.
Also the string should be well defined before head (for example, from
message.ToString). The MegSeqNum issue also needs to be considered.

So far so good, and I did successfully send out the message by this way.
By using FIX::Session::send ( const std::string& string ), the latency for
sending message is significantly reduced.

BUT, here is the problem.

if I do message.ToString > FIX::Session::send ( const std::string& string ), 
then the message is sent successfully.
if I do message.ToString > modify this string (for example, COrderID from
12345 to 54321)> FIX::Session::send ( const std::string& string ), the
message will be written on the log file (or shown on the screen logger)
saying it is outgoing, but the server would never respond, which suggesting
this message want sent out.

What is interesting is, if I do 
do message.ToString > modify this string (COrderID from 12345 to 54321 by
string.erase and then string insert)> modify this string (COrderID from
54321 back to 12345) > FIX::Session::send ( const std::string& string )  
then this is successful.

This is very weird to me, and it seems the message.ToString automatically
set up some flag, and the FIX::Session::send will check that flag (to see if
message and message.ToString are matched). 
I read hose code, but didnt find such a thing.

So, my question is, 
why the modification after message.ToString makes FIX::Session::send ( const
std::string& string ) failed?

Many thanks
Wjack





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