Merge another big set of changes from team/russell/events

This commit merges in the rest of the code needed to support distributed device
state.  There are two main parts to this commit.

Core changes:
 - The device state handling in the core has been updated to understand device
   state across a cluster of Asterisk servers.  Every time the state of a device
   changes, it looks at all of the device states on each node, and determines the
   aggregate device state.  That resulting device state is what is provided to
   modules in Asterisk that take actions based on the state of a device.

New module, res_ais:
 - A module has been written to facilitate the communication of events between
   nodes in a cluster of Asterisk servers.  This module uses the SAForum AIS
   (Service Availability Forum Application Interface Specification) CLM and EVT
   services (Cluster Management and Event) to handle this task.  This module
   currently supports sharing Voicemail MWI (Message Waiting Indication) and
   device state events between servers.  It has been tested with openais, though
   other implementations of the spec do exist.

For more information on testing distributed device state, see the following doc:
  - doc/distributed_devstate.txt


git-svn-id: http://svn.digium.com/svn/asterisk/trunk@121559 f38db490-d61c-443f-a65b-d21fe96a405b

1 files changed, 310 insertions, 0 deletions

diff --git a/doc/distributed_devstate.txt b/doc/distributed_devstate.txt
new file mode 100644
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+++ b/doc/distributed_devstate.txt
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+===============================================================================
+===
+=== Distributed Device State
+===
+=== Copyright (C) 2007-2008, Digium, Inc.
+=== Russell Bryant <russell@digium.com>
+===
+===============================================================================
+
+-------------------------------------------------------------------------------
+--- 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-events
+$ ./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-events
+$ 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>.
+
+-------------------------------------------------------------------------------