[Serusers] More detailed explanation of t_newtran needed.

[Younger Wang]

Simplified code:

if(method=="INVITE")  {
    t_newtran();
    t_relay();
    };

If the same INVITE is received twice, it will be processed only for one
time. However if the same INVITE is sent three times,
this INVITE will be processed when the second transmission is received.  So
I wonder, if the third transmission is received, the process will trap in
t_newtran() and will never return until a timeout is reached?

Younger Wang


----- Original Message ----- 
From: "Jiri Kuthan" <jiri at iptel.org>
To: "Younger Wang" <wygmail at yeah.net>; <serusers at lists.iptel.org>
Sent: Wednesday, June 18, 2003 1:51 PM
Subject: Re: [Serusers] More detailed explanation of t_newtran needed.


> At 12:55 AM 6/19/2003, Younger Wang wrote:
> >I am trying to understand how tm module works.
> >
> >I found in http://www.iptel.org/ser/doc/prerelease/x545.html--->Stateful
> >User Agent Server:
> >______________________________________________
> >t_newtran shields subsequent code from retransmissions. It returns
success
> >and continues when a new request arrived. It exits current route block
> >immediately on receipt of a retransmissions.
> >-----------------------------------------------
> >I found in the README included in tm module:
> >_______________________________________________
> >Name: t_newtran
> >Params: 0
> >Desc: creates a new transaction, returns a negative value on
> >     error; this is the only way a script can add a new transaction
> >     in an atomic way; typically, it is used to deploy a UAS
> >-----------------------------------------------
> >
> >I think the two explanations above are inconsistent.
>
> I don't think so.
>
> >I am quite confused.
> >Take the scripts below for example:
> >_______________________________
> >if ( !t_newtran()) {
> >  sl_reply_error();
> >  break;
> > };
> >
> > # the following log will be only printed on receipt of
> > # a new message; retranmissions are absorbed by t_newtran
> > log(1, "New Transaction Arrived\n");
> > if (uri=~"a@") {
> >  if (!t_reply("409", "Bizzar Error")) {
> >   sl_reply_error();
> >  };
> > } else {
> >  if (!t_reply("699", "I don't want to chat with you")) {
> >   sl_reply_error();
> >  };
> >    };
> >-------------------------------
> >
> >My understanding is: If t_newtran() returns successfully, the scripts
will
> >not execute forward until a new message rather than retransmission of the
> >original message is received. Am I right?
>
> I don't know since I don't parse your message quite. If t_newtran returns
> successfuly, it indicates a new request which should be processed. It is
> an error otherwise. Retransmissions cause immediate leave of script
processing.
>
> -jiri
>
> >If wrong, how does it work
> >actually?
> >
> >Thanks!
> >
> >Younger Wang
> >
> >_______________________________________________
> >Serusers mailing list
> >serusers at lists.iptel.org
> >http://lists.iptel.org/mailman/listinfo/serusers
>
> --
> Jiri Kuthan            http://iptel.org/~jiri/
>