git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@179164 65c4cc65-6c06-0410-ace0-fbb531ad65f3
321 lines
12 KiB
Text
321 lines
12 KiB
Text
===============================================================================
|
|
===
|
|
=== Distributed Device State
|
|
===
|
|
=== Copyright (C) 2007-2008, Digium, Inc.
|
|
=== Russell Bryant <russell@digium.com>
|
|
===
|
|
===============================================================================
|
|
|
|
-------------------------------------------------------------------------------
|
|
--- IMPORTANT NOTE
|
|
-------------------------------------------------------------------------------
|
|
|
|
This document includes some information about using the res_ais module for
|
|
distributed events. However, it is important to note that res_ais is still
|
|
considered experimental, as the module exposes the binary format of events
|
|
over the network between servers. This format is still subject to change
|
|
between 1.6.X releases.
|
|
|
|
-------------------------------------------------------------------------------
|
|
--- INTRODUCTION
|
|
-------------------------------------------------------------------------------
|
|
|
|
Various changes have been made related to "event handling" in Asterisk.
|
|
One of the most important things included in these changes is the ability
|
|
to share certain events between servers. The two types of events that can
|
|
currently be shared between servers are:
|
|
|
|
1) MWI - Message Waiting Indication
|
|
- This gives you a high performance option for letting servers in a
|
|
cluster be aware of changes in the state of a mailbox. Instead of
|
|
having each server have to poll an ODBC database, this lets the server
|
|
that actually made the change to the mailbox generate an event which
|
|
will get distributed to the other servers that have subscribed to this
|
|
information.
|
|
|
|
2) Device State
|
|
- This lets servers in a local cluster inform each other about changes in
|
|
the state of a device on that particular server. When the state of a
|
|
device changes on any server, the overall state of that device across
|
|
the cluster will get recalculated. So, any subscriptions to the state
|
|
of a device, such as hints in the dialplan or an application like
|
|
Queue() which reads device state, will then reflect the state of a
|
|
device across a cluster.
|
|
|
|
-------------------------------------------------------------------------------
|
|
|
|
-------------------------------------------------------------------------------
|
|
--- OpenAIS Installation
|
|
-------------------------------------------------------------------------------
|
|
|
|
--- Description ---
|
|
|
|
The current solution for providing distributed events with Asterisk is done by
|
|
using the AIS (Application Interface Specification), which provides an API for
|
|
a distributed event service. While this API is standardized, this code has
|
|
been developed exclusively against the open source implementation of AIS called
|
|
OpenAIS.
|
|
|
|
For more information about OpenAIS, visit their web site:
|
|
|
|
http://www.openais.org/
|
|
|
|
--- Download ---
|
|
|
|
To quickly downlaod OpenAIS, just check it out of svn:
|
|
|
|
$ svn co http://svn.osdl.org/openais/trunk openais-trunk
|
|
|
|
--- Compile ---
|
|
|
|
$ cd openais-trunk
|
|
$ make PREFIX=/usr
|
|
|
|
--- Install ---
|
|
|
|
By default, the current Makefile installs the libraries into /usr/lib/openais/,
|
|
which is a little bit inconvenient. So, open up the Makefile, find the lines
|
|
that start with "LIBDIR=" to define the lib installation directory, and remove
|
|
the trailing "openais" so it just gets installed in /usr/lib/.
|
|
|
|
$ sudo make install PREFIX=/usr
|
|
|
|
-------------------------------------------------------------------------------
|
|
|
|
-------------------------------------------------------------------------------
|
|
--- OpenAIS Configuration
|
|
-------------------------------------------------------------------------------
|
|
|
|
Basic OpenAIS configuration to get this working is actually pretty easy. When
|
|
you install it, it will put some default configuration files into /etc/ais/.
|
|
Edit openais.conf ...
|
|
|
|
$ ${EDITOR:-vim} /etc/ais/openais.conf
|
|
|
|
The only section that you should need to change is the totem - interface
|
|
section.
|
|
|
|
totem {
|
|
...
|
|
interface {
|
|
interface {
|
|
ringnumber: 0
|
|
bindnetaddr: 10.19.0.0
|
|
mcastaddr: 226.94.1.1
|
|
mcastport: 5405
|
|
}
|
|
}
|
|
|
|
The default mcastaddr and mcastport is probably fine. But, you need to change
|
|
the bindnetaddr to match the network address that the nodes of your cluster
|
|
will communicate on.
|
|
|
|
The one other thing that you need to do is create a user called "ais".
|
|
|
|
$ sudo adduser ais
|
|
|
|
See the OpenAIS QUICKSTART file for more information on installing,
|
|
configuring, and testing OpenAIS.
|
|
|
|
$ cd openais-trunk
|
|
$ less QUICKSTART
|
|
|
|
-------------------------------------------------------------------------------
|
|
|
|
-------------------------------------------------------------------------------
|
|
--- Running OpenAIS
|
|
-------------------------------------------------------------------------------
|
|
|
|
While testing, I would recommend starting the aisexec application in the
|
|
foreground so that you can see debug messages that verify that the nodes have
|
|
discovered each other and joined the cluster.
|
|
|
|
$ sudo aisexec -f
|
|
|
|
-------------------------------------------------------------------------------
|
|
|
|
-------------------------------------------------------------------------------
|
|
--- Installing Asterisk
|
|
-------------------------------------------------------------------------------
|
|
|
|
Install Asterisk as usual. Just make sure that you run the configure script
|
|
after OpenAIS gets installed. That way, it will find the AIS header files and
|
|
will let you build the res_ais module. Check menuselect to make sure that
|
|
res_ais is going to get compiled and installed.
|
|
|
|
$ cd asterisk-source
|
|
$ ./configure
|
|
|
|
$ make menuselect
|
|
---> Resource Modules
|
|
|
|
If you have existing configuration on the system being used for testing, just
|
|
be sure to install the addition configuration file needed for res_ais.
|
|
|
|
$ sudo cp configs/ais.conf.sample /etc/asterisk/ais.conf
|
|
|
|
-------------------------------------------------------------------------------
|
|
|
|
-------------------------------------------------------------------------------
|
|
--- Configuring Asterisk
|
|
-------------------------------------------------------------------------------
|
|
|
|
First, ensure that you have a unique "entity ID" set for each server.
|
|
|
|
*CLI> core show settings
|
|
...
|
|
Entity ID: 01:23:45:67:89:ab
|
|
|
|
The code will attempt to generate a unique entity ID for you by reading
|
|
MAC addresses off of a network interface. However, you can also set it
|
|
manually in the [options] section of asterisk.conf.
|
|
|
|
$ sudo ${EDITOR:-vim} /etc/asterisk/asterisk.conf
|
|
|
|
[options]
|
|
...
|
|
entity_id=01:23:45:67:89:ab
|
|
|
|
|
|
Edit the Asterisk ais.conf to enable distributed events. For example, if you
|
|
would like to enable distributed device state, you should add the following
|
|
section to the file:
|
|
|
|
$ sudo ${EDITOR:-vim} /etc/asterisk/ais.conf
|
|
|
|
[device_state]
|
|
type=event_channel
|
|
publish_event=device_state
|
|
subscribe_event=device_state
|
|
|
|
For more information on the contents and available options in this configuration
|
|
file, please see the sample configuration file:
|
|
|
|
$ cd asterisk-source
|
|
$ less configs/ais.conf.sample
|
|
|
|
-------------------------------------------------------------------------------
|
|
|
|
-------------------------------------------------------------------------------
|
|
--- Basic Testing of Asterisk with OpenAIS
|
|
-------------------------------------------------------------------------------
|
|
|
|
If you have OpenAIS successfully installed and running, as well as Asterisk
|
|
with OpenAIS support successfully installed, configured, and running, then you
|
|
are ready to test out some of the AIS functionality in Asterisk.
|
|
|
|
The first thing to test is to verify that all of the nodes that you think should
|
|
be in your cluster are actually there. There is an Asterisk CLI command which
|
|
will list the current cluster members using the AIS Cluster Membership Service
|
|
(CLM).
|
|
|
|
*CLI> ais clm show members
|
|
|
|
=============================================================
|
|
=== Cluster Members =========================================
|
|
=============================================================
|
|
===
|
|
=== ---------------------------------------------------------
|
|
=== Node Name: 10.19.2.255
|
|
=== ==> ID: 0xa1302ff
|
|
=== ==> Address: 10.19.2.255
|
|
=== ==> Member: Yes
|
|
=== ---------------------------------------------------------
|
|
===
|
|
=== ---------------------------------------------------------
|
|
=== Node Name: 10.19.6.187
|
|
=== ==> ID: 0xa1306bb
|
|
=== ==> Address: 10.19.6.187
|
|
=== ==> Member: Yes
|
|
=== ---------------------------------------------------------
|
|
===
|
|
=============================================================
|
|
|
|
|
|
The next thing to do is to verify that you have successfully configured some
|
|
event channels in the Asterisk ais.conf file. This command is related to the
|
|
event service (EVT), so like the previous command, uses the syntax:
|
|
"ais <service name> <command>".
|
|
|
|
*CLI> ais evt show event channels
|
|
|
|
=============================================================
|
|
=== Event Channels ==========================================
|
|
=============================================================
|
|
===
|
|
=== ---------------------------------------------------------
|
|
=== Event Channel Name: mwi
|
|
=== ==> Publishing Event Type: mwi
|
|
=== ==> Subscribing to Event Type: mwi
|
|
=== ---------------------------------------------------------
|
|
===
|
|
=== ---------------------------------------------------------
|
|
=== Event Channel Name: device_state
|
|
=== ==> Publishing Event Type: device_state
|
|
=== ==> Subscribing to Event Type: device_state
|
|
=== ---------------------------------------------------------
|
|
===
|
|
=============================================================
|
|
|
|
-------------------------------------------------------------------------------
|
|
|
|
-------------------------------------------------------------------------------
|
|
--- Testing Distributed Device State
|
|
-------------------------------------------------------------------------------
|
|
|
|
The easiest way to test distributed device state is to use the DEVICE_STATE()
|
|
diaplan function. For example, you could have the following piece of dialplan
|
|
on every server:
|
|
|
|
[devstate_test]
|
|
|
|
exten => 1234,hint,Custom:mystate
|
|
|
|
exten => set_inuse,1,Set(DEVICE_STATE(Custom:mystate)=INUSE)
|
|
exten => set_not_inuse,1,Set(DEVICE_STATE(Custom:mystate)=NOT_INUSE)
|
|
|
|
exten => check,1,NoOp(Custom:mystate is ${DEVICE_STATE(Custom:mystate)})
|
|
|
|
|
|
Now, you can test that the cluster-wide state of "Custom:mystate" is what
|
|
you would expect after going to the CLI of each server and adjusting the state.
|
|
|
|
server1*CLI> console dial set_inuse@devstate_test
|
|
...
|
|
|
|
server2*CLI> console dial check@devstate_test
|
|
-- Executing [check@devstate_test:1] NoOp("OSS/dsp", "Custom:mystate is INUSE") in new stack
|
|
|
|
Various combinations of setting and checking the state on different servers can
|
|
be used to verify that it works as expected. Also, you can see the status of
|
|
the hint on each server, as well, to see how extension state would reflect the
|
|
state change with distributed device state:
|
|
|
|
server2*CLI> core show hints
|
|
-= Registered Asterisk Dial Plan Hints =-
|
|
1234@devstate_test : Custom:mystate State:InUse Watchers 0
|
|
|
|
|
|
One other helpful thing here during testing and debugging is to enable debug
|
|
logging. To do so, enable debug on the console in /etc/asterisk/logger.conf.
|
|
Also, enable debug at the Asterisk CLI.
|
|
|
|
*CLI> core set debug 1
|
|
|
|
When you have this debug enabled, you will see output during the processing of
|
|
every device state change. The important thing to look for is where the known
|
|
state of the device for each server is added together to determine the overall
|
|
state.
|
|
|
|
-------------------------------------------------------------------------------
|
|
|
|
|
|
-------------------------------------------------------------------------------
|
|
--- Question, Comments, and Bug Reports
|
|
-------------------------------------------------------------------------------
|
|
|
|
For now, please direct all feedback to Russell Bryant <russell@digium.com>.
|
|
|
|
-------------------------------------------------------------------------------
|