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

[Sev Z. <se...@gm...>]

Regarding your experiment with modifying the output of message.ToString, 
I think that once you modify the string, you'll invalidate the 
CheckSum(10) field that QuickFix appends to the end of each message.

On 7/6/2014 5:30 AM, Wjack07 wrote:
> QuickFIX Documentation: http://www.quickfixengine.org/quickfix/doc/html/index.html
> QuickFIX Support: http://www.quickfixengine.org/services.html
>
> 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
>
>
>
>
>
> --
> View this message in context: http://quickfix.13857.n7.nabble.com/Problem-with-Session-send-const-std-string-string-tp6646.html
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>
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