[OpenSIPS-Users] [RFC] OpenSIPS 2.0 - changes on the SIP messages

[Bogdan-Andrei Iancu]

Hi,

sorry for crossposting, but I thing this topic is interesting both for 
users (as experience) and for developers (as solution).

So, right now the code for 2.0 got to a stage were we need to "apply" 
changes on the received messages (like adding VIA headers, changing 
headers, etc). And before starting the work on this area, I would like 
to get some opinions on the available options:

    1) keep the current mechanism for changing the SIP messages by using 
lumps that are applied only when the message is sent out :
       Advantages: code is there and works; the mechanism is very fast ; 
no need to re-parse the message after the parsing
       Disadvantages : from script or code, you are not able to see the 
previous changes you did on the message, like:
                 if you remove a hdr, it will be marked to be removed, 
but you will still see it there after the removed
                 if you add a new hdr, you will not be able to see it 
(it will be actually added only when the message will be sent out)
                 if you replace the contact hdr (like after 
fix_nated_contact() ) will not see the new contact, but the old one
                 trying to apply 2 changes in the same area (like 
changing twice the contact) will result in bogus result.

    2) find a new approach that will allow to push in realtime the 
changes on messages
       Advantages: the change will take affect instantly, so all the 
disadvantages from 1) (as user experience in operating opensips) will 
disappear .
       Disadvantages : the code will probably be slower (the changes 
part), but will speed up other parts of the code (where you need to 
manually identify the prev changes);
             changed parts of the SIP message will require re-parsing 
(so the code will have to check the state of a header (if parsed or not) 
before each usage)
             you will not be able to undo changes on the SIP messages in 
an easy way (for example during the parallel and serial forking on 
per-branch changes)

So this is the dilemma: if the current mechanism (with applying changes 
at the end) such a bad user experience (scripting) in order to try for 
2.0 a different approach ?

I would like to hear some opinions from both people writing scripts and 
people writing code.

Thanks and regards,
Bogdan

-- 
Bogdan-Andrei Iancu
www.voice-system.ro