I'd vote for dmq and 'request-for-update'. As a mechanism to reject calls
I'd suggest exporting the "status" function giving 1\-1 depending on
whether we've received the latest state or not.
Couple of notes though:
1. All updates should have some sort of sequence numbers(?) otherwise there
could appear conflicts.
2. During the 'getting the state' time kamailio should queue new messages
or we'll never have a consistent data across the servers.
So after all the best option looks like the hardest one =)
BTW, why not relying on some 3rd party DB's replication for syncing
profiles and data? So each kamailio works with local storage and the
storage solves the master-master replication.
2014-08-22 18:52 GMT+04:00 Daniel-Constantin Mierla <miconda(a)gmail.com>om>:
Hello,
if you are on sr-dev list, you should have seen the last commits to dialog
module, which add support for remote profiles.
As most of you know (or at least the users of dialog module), profiles are
used to group active calls, their main purposes being counting dialogs
belonging to a profile for implementing active call limits (e.g., all calls
in the system, call from/to a specif user/address).
It was working on a single Kamailio instance, but one could use other
meanings to interact with other kamailio instance to get the number of
calls across multiple instances.
The purpose of remote profiles is to make the whole process easier and
more transparent for config file, simplifying the maintenance.
A remote profile is an item stored in local profile list not bound to a
local dialog. At this moment, dialog module in master branch exports a
function dlg_remote_profile() that allows to add/remove a remote profile.
The next step is to build the notification system between kamailio
instances. There are couple of options, as well as questions, that I want
to discuss before going to implement the mechanism. There are two major
aspects to care of:
A) Distribution, I thought of two options for it:
1) using dmq module to publish the operations done with local profiles
(add/remove) -- this seems to be the natural choice right now, Charles
Chance is also willing to put effort in this direction
This will be coded inside the module, so config won't be affected much
(eventually some extra parameters of dialog flags).
2) add event routes for adding/removing a local profile. The attributes of
the profile can be made available via some PV, then in config use what so
ever option (e.g., http query, json rpc, etc) for distributing the
information.
This will require changes in config file and might not be trivial for new
users
B) Persistence, with the options:
1) store remote profiles in local database.
It is good for restart, but if there is big downtime, then some
notifications can be lost and the list of remote profiles might be
inaccurate
2) keep in memory only and at startup send a 'request-for-update' to the
other instances -- these instances will send the list of their local
profiles.
It can take a bit between request-for-update and receiving data from the
other servers -- during this interval, the checks of overall call limits
might not give the desired answer
Of course, there can be enhancements/combinations, but it has to be
analysed if the benefit worth the complexity. For 1), store also the IP of
each remote profile and then interrogate for each profile to see if its
still active. For 2), add a mechanism to reject new calls until the
request-for-update is completed.
Anyone having other ideas or comments to the above?
Note that each profile got a unique id, so if you upgrade your dialog
module, profiles for existing active calls will not be loaded. Also, the
code was barely tested, report here any issue you have with dialog from
master branch.
Cheers,
Daniel
--
Daniel-Constantin Mierla
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http://www.linkedin.com/in/miconda
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