[Users] ACK processing

[Michael Ulitskiy]

I must confess that first time wiki editing has been a challenge due
to it doesn't work well with konqueror - my default browser of choice.
It took me some time to figure it out :)

Michael

On Wednesday 27 July 2005 01:19 pm, Bogdan-Andrei Iancu wrote:
> Hi Michael,
> 
> it will be really cool if you could add all the info related to CANCEL 
> and ACK routing and tm behaviour into the wiki. All docs from wiki will 
> go for sure into cvs and web docs.
> 
> thanks and regards,
> bogdan
> 
> Michael Ulitskiy wrote:
> 
> >Hi Bogdan,
> >
> >Yeap, I've already figured it out by experimenting.
> >Thanks a lot for clarification. 
> >I couldn't find clear description of this tm module behavior
> >anywhere in documentation or on the web.
> >I think it's worth to put your replies in this thread in 
> >FAQ/documentation/etc. I find it quite confusing figuring it
> >out on your own.
> >
> >Michael
> >
> >
> >On Wednesday 27 July 2005 12:03 pm, you wrote:
> >  
> >
> >>Hi Michael,
> >>
> >>what to do with broken hop-by-hop ACKs ? :) just drop them, otherwise 
> >>they will loop on the server.
> >>
> >>t_newtran() basically creates a new transaction. If it's ACK and it 
> >>matched to an INVITE transaction, it will be silently discarded (so 
> >>function will never return to script). If ACk doesn't match, the 
> >>function will return; so after t_newtran() you will have only unmatched 
> >>ACKs filtered out.
> >>
> >>so,
> >>
> >>.....
> >>if (is_method("ACK")) { #hop-by-hop ACKs are absorbed here
> >>    t_newtran();
> >>    # drop broken ACKs
> >>    exit;
> >>}
> >>......
> >>
> >>
> >>should be ok.
> >>
> >>regards,
> >>bogdan
> >>
> >>Michael Ulitskiy wrote:
> >>
> >>    
> >>
> >>>Bogdan,
> >>>
> >>>Thanks a lot. Your replies are very useful.
> >>>Just couple more questions raised by comments.
> >>>What would I want to do with broken ACKs? I thought I'd just drop it.
> >>>Also how would I distinguish them? I don't really understand how
> >>>you use t_newtran(). Don't real ACKs still need to hit t_relay to
> >>>finish transaction?
> >>>I thought about something like the following, but so far couldn't find
> >>>a way to determine if ACK is matching transaction or not:
> >>>
> >>>if (is_method("ACK")) { #hop-by-hop ACKs are absorbed here
> >>>    if (in-transaction ACK) {
> >>>       t_relay();
> >>>    }
> >>>    # lost ACKs are dropped
> >>>    # .......
> >>>    exit;
> >>>}
> >>>
> >>>I've tried to t_lookup_request() to check if it's in transaction, but it didn't work.
> >>>Could you please comment on it?
> >>>Thanks,
> >>>
> >>>Michael
> >>>
> >>>On Tuesday 26 July 2005 06:55 am, you wrote:
> >>> 
> >>>
> >>>      
> >>>
> >>>>Hi Michael,
> >>>>
> >>>>that's ok. only two comments:
> >>>>1) all ACKs are in-dialog: ACKs for negative replies are hop-by-hop and 
> >>>>are the one absorbed by tm functions; the ACKs for 2xx replies are 
> >>>>end-to-end and are Route driven.
> >>>>2) since you may have hop-by-hop ACKs (no route) which doesn't match any 
> >>>>transaction (broken or lost ACKs), if you want to deal with them 
> >>>>separately, do like this:
> >>>>  
> >>>>
> >>>>if (loose_route()) { #end-2-end ACKs are forwarded here
> >>>>   #do something 
> >>>>   t_relay();
> >>>>   exit;
> >>>>}
> >>>>if (is_method("ACK")) { #hop-by-hop ACKs are absorbed here
> >>>>   t_newtran();
> >>>>   # deal with broken / lost ACKs
> >>>>   # .......
> >>>>   exit;
> >>>>}
> >>>>
> >>>>
> >>>>regards,
> >>>>bogdan
> >>>>   
> >>>>
> >>>>        
> >>>>
> >
> >  
> >
> 
>