[Serdev] A suggestion for how SER should focus - was: So who/what is SER for, anyway?

[Martin Hoffmann]

Greger V. Teigre wrote:
>  
> "replicating its transaction state", you mean a SIP transaction?  If 
> that's what you mean, this is an example of why telco-apps get so 
> expensive. What if the server goes down in the middle of the 
> transaction?  It fails, hey, that's a bummer, so it has to be resent, by 
> the UAS. Why would you spent an immense amount of money to make sure 
> that the transaction can fail over?! 

INVITE transactions can go on for a very long time (technically,
forever) and, what's more important, their progress is user visible. It
actually does make sense to continue them on a stand-by box if the
primary box fails.[0] For everything else resent is good enough.

Regards,
Martin

[0] IMHO, this is a flaw in SIP. Instead of one very long transaction
    with a three-way handshake and related extra transactions on the
    side (PRACK), a series of short transactions would have been better.