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

[Bogdan-Andrei Iancu]

Hi Emmanuel,


Emmanuel BUU wrote:
> Hello,
>
> First of all, I want to stress that the whole concept of message 
> scripting is a fabulous asset. It enables us
> to adapt to so many situations without recompling C code. I have the 
> feeling that the whole concept has emerged from a rather practical
> and performance oriented approach (which is good).
and we do not want to loose that :)
>  We should maybe look 
> at what we idealy would like:
>
> We want to be able to modify the message and see the modification "in 
> real time". 
yes, that is one of the major draw backs at the current time.
> For some values,
> we also want either to undo some changes (mainly the module developpers) 
> or access the original values
> the scripts writers.
>
> So IMHO there should be some place where the original message stand, 
> preparsed by the core. The modifications should be applied on a 
> preparsed copy
> and the module developper should be able to access both but modify only 
> the one that is intented to handle the modification. At the end of the 
> processing
> the modified message should be translated from a parsed form to a text 
> buffer.
>
> This process might be slower than the original lump model that is highly 
> optimized but it may lead to a more sold ground.
>   
See my suggetion here  - 
http://lists.opensips.org/pipermail/users/2010-April/012401.html

Maybe I should try to place it on wiki to be easier to read ;)
> I agree with the remark about branch isolation.
>   

thanks,
Bogdan
> Emmauel
>
> Bogdan-Andrei Iancu a écrit :
>   
>> 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
>>
>>   
>>     
>
>
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>   


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