[Asterisk-Dev] Manager XML

[Chris Howard]

----- Original Message ----- 
From: "Adam Goryachev" <mailinglists at websitemanagers.com.au>
> So, perhaps we need to simplify the manager interface, and return it
> back to a pure event broadcast system, and add another interface which
> we can send/receive request/responses in. As far as the format that we
> would submit the requests in, and the format to receive the response in,
> I don't really want to comment on too much. tag:value seems very
> flexible/extensible, and seems to work quite well for every case I've
> seen. However, I am sure there are cases where XML would be ... more
> convenient... but I'm not convinced we couldn't still do all this in
> tag:value format....

Adam,
  I agree with you that the interface should be divided into two separate 
interface.  One for system events and the other for action/response 
messages.  The problem is that the interface is not consistent.  Some 
actions generate responses as in "Action: MailboxStatus" and other actions 
generate events as in "Action: Status". This makes it very hard to separate 
them.

Distributing/broadcasting Events and accepting Actions/Resonses from/to 
clients is a different story.  What we needed was some sort of message bus 
that the asterisk manager could broadcast event messages to all client  as 
well as  receive actions and send responses  in a peer to peer fashion.  We 
looked at various middleware solutions and none really seem to fit what we 
were trying to do.  As pure message oriented middleware  Spread seems to be 
the best fit but there was an issue (I can't remember what it was) that kept 
us from using it.  We came up with what I think is a very unusual but 
creative solution of using  an IRC server as the message bus.  We created a 
server proxy using the very well designed asterisk-java package.  This proxy 
logs into the ircserver and joins a channel.  All of the events that are not 
filtered by this proxy server are sent to the channel is a format we 
defined.  Multiple proxies from multiple asterisk servers can join the same 
channel and send events.  The client applications login to the IRC server 
and join a channel.  All of the broadcast events are sent to the channel and 
the client can deal with these events however it wishes.  For the 
Action/Response the client sends a private message to the proxy irc user and 
the receives a response via private message from the proxy.   We use a 
modified version of pircd as the IRC server (stripped out throttling and 
other unneeded "features"). It would probably be very easy to replace the 
IRC server with a more traditional message oriented middleware if scaling 
was ever an issue however as far as I know IRC scales very well. I can write 
up a more detailed explanation and throw the code on a cvs server if there 
is any interest.

Chris Howard
Asteria Solutions Group

office:    256.705.0262
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