Logging to GTalk

ComputingOpen SourceVoIP

I was reading yesterday that Apple is thought to be using XMPP the Jabber protocol for their new iPhone Push Notification technology.

That’s funny I thought, I had just started using XMPP for logging!!!

I am experimenting with Asterisk at the moment. Asterisk for those that do not know is an Open Source PBX (Private Branch Exchange) a phone system in software. I have it running on my ancient 500 Mhz Mac Cube, it has been extremely reliable. My home office now has a ridiculously sophisticated phone system ;-)

IMHO most of the monitoring tools for Asterisk suck. They are written in nasty languages like PHP, Perl, Flash etc. that not only do I not want on my system, they are overkill.

What I wanted was to receive simple messages about the run-time status of the system. I wanted to be able to receive these messages securely, from wherever I was (because I can use my phone system from wherever I am, but more on that another time).

Asterisk has a Jabber module, so this was an easy way to go.

So, I have two GMail Accounts, one for personal email, one for mailing lists. I have iChat on my desktop/laptop/iPhone already subscribed to GTalk on my personal GMail account.

First I added my spare GTalk account as a buddy to my personal account (requires some fiddling around, but if you know your IM client, it’s pretty easy).

Then I configured Asterisk (beware, she’s a complex beast, BTW a semi-colon marks a comment).

First configure /etc/asterisk/jabber.conf :

debug=yes ;Turn on debugging by default.
autoprune=no ;Auto remove users from buddy list.
autoregister=no ;do not auto register users from buddy list.

[gtalk-logger] ;label
type=client ;Client or Component connection
username=MY_SPARE_GTALK_USERNAME@gmail.com/asterisk ;Username with optional roster.
secret=************** ;Password for MY_SPARE_GTALK_USERNAME
port=5222 ;Port to use defaults to 5222
usetls=yes ;Use tls or not
usesasl=yes ;Use sasl or not
buddy=MY_MAIN_GTALK_USERNAME@gmail.com ;Manual addition of buddy to list.
statusmessage=Up and Running ;custom status message for Asterisk.
timeout=100 ;Timeout on the message stack.`

This allows Asterisk to connect to GTalk to send messages.

The next thing to do is to emit messages from the appropriate parts of your dialplan.

First I defined a Macro, that can be used from anywhere in the dialplan, this goes in /etc/asterisk/extensions.conf :

; log message - to Jabber
; @param ${ARG1} - the message to send
exten => s,,Jabbersend(gtalk-logger,MY_MAIN_GTALK_USERNAME@gmail.com,${STRFTIME(${EPOCH},GMT,%C%y-%m-%d %H:%M%n)} ${ARG1})

This sends the message in $ARG1 with a timestamp.

Next is to use the macro from the dialplan. Here is an example of an outbound route to go via SipBroker, matching dialed numbers beginning with * :

  exten => _*X.,1,Macro(logger,Outbound call to ${EXTEN} via SipBroker) ; log the call
  exten => _*X.,2,Set(CALLERID(all)=${JQNAME} <${JQOFFICE}>)  ; Set outbound CallerID
  exten => _*X.,3,ChanIsAvail(SIP/${EXTEN}@sipbroker,j) ; Check to see if available (jumps to priority + 101 on fail)
  exten => _*X.,4,Dial(SIP/${EXTEN}@sipbroker,,tTW) ; Dial, allowing transferring and recording
  exten => _*X.,5,Macro(dial-result) ; Check result
  exten => _*X.,104,Playback(all-circuits-busy-now) ; if ChanIsAvail fails, say message

I know, it looks really weird !!!! :-)

I left out a few details like, looking up the phone number in my AddressBook.app to show the recipient’s name and using Growl.app to splash these messages received by iChat. I plan to cover these in a subsequent post.

I have found this to be a really simple and reliable solution.

There are XMPP libraries for many systems, I may start using this technique elsewhere as well.