Reliable-msg-agent

reliable-msg-agent is consumer for reliable-msg.

The pull type approach that acquires the message accumulated in A and processes it is taken.

System configuration

+-------------+
| Application |
+-------------+
      |
      | Push Message
      +
+-------------+
| ReliableMsg |+------+
+-------------+       |
      +               | <-- Agent regularly acquires
      |               |      the message from ReliableMsg.
      +               +
  +-------+       +-------+
  | Agent |  ...  + Agent +
  +-------+       +-------+

Getting started 1

Install

gem install reliable-msg-agent

Start reliable-msg

reliable-msg is started beforehand.

$ queues manager start
I, [2011-04-03T23:00:43.781875 #1856]  INFO -- : Created queues configuration file in: /usr/loc...
I, [2011-04-03T23:00:43.781875 #1856]  INFO -- : Using message store: disk
I, [2011-04-03T23:00:43.812875 #1856]  INFO -- : Accepting requests at: druby://localhost:6438

Start reliable-msg-agent

$ reliable-msg-agent start
*** Starting ReliableMsg-Agent...
I, [2011-04-03T23:02:11.390875 #2724]  INFO -- : *** reliable-msg agent service starting...
I, [2011-04-03T23:02:11.390875 #2724]  INFO -- : --- starting workers.
I, [2011-04-03T23:02:11.452875 #2724]  INFO -- : *** reliable-msg agent service started.

Push message to reliable-msg queue.

The message “foo” is push to queue of reliable-msg.

$ irb -rubygems -rreliable-msg
irb(main):001:0> ReliableMsg::Queue.new("queue.agent").put("foo")
 => "0d98c020-402a-012e-f635-000ae47391e2"
irb(main):002:0> exit
$

The console that executes reliable-msg-agent is seen.

The message is acquired from reliable-msg, and the log is output.

$ queues manager start
I, [2011-04-03T23:13:41.046875 #3860]  INFO -- : *** reliable-msg agent service starting...
I, [2011-04-03T23:13:41.046875 #3860]  INFO -- : --- starting workers.
I, [2011-04-03T23:13:41.093875 #3860]  INFO -- : *** reliable-msg agent service started.
I, [2011-04-03T23:14:24.280875 #3860]  INFO -- : message fetched - <9957e5a0-402a-012e-f635-000ae47391e2>
I, [2011-04-03T23:14:24.280875 #3860]  INFO -- : message received
--- !ruby/object:ReliableMsg::Message
headers:
  :delivery: :best_effort
  :max_deliveries: 5
  :created: 1301840063
  :id: 9957e5a0-402a-012e-f635-000ae47391e2
  :expires:
  :priority: 0
id: 9957e5a0-402a-012e-f635-000ae47391e2
object: foo

Getting started 2 - The behavior when the message is acquired is changed.

Default operation of reliable-msg-agent is only a log output. This can be changed.

Start reliable-msg

reliable-msg is started beforehand.

$ queues manager start
I, [2011-04-03T23:00:43.781875 #1856]  INFO -- : Created queues configuration file in: /usr/loc...
I, [2011-04-03T23:00:43.781875 #1856]  INFO -- : Using message store: disk
I, [2011-04-03T23:00:43.812875 #1856]  INFO -- : Accepting requests at: druby://localhost:6438

Preparation for configuration file

The file /etc/reliable-msg-agent.conf of the following content is prepared.

# /etc/reliable-msg-agent.conf
---
agent: /etc/reliable-msg-agent.rb
consumers:
  -
    source_uri: druby://localhost:6438
    every: 1.0
    target: queue.agent
    threads: 1

In addition, the file /etc/reliable-msg-agent.rb of the following content is prepared. Here, the directory specified by the message is made.

# /etc/reliable-msg-agnet.rb
require "fileutils"

# The method of processing the message is defined.
#
# if the evaluation result is nil or false,
# it is considered that it failes.
#
# === Args
#
# +msg+     :: fetched message from reliable-msg queue.
# +conf+    :: consumer configurations.
# +options+ :: the options (it is still unused.)
#
def call msg, conf, options = {}
  dir = File.join "/tmp", msg.object
  FileUtils.mkdir_p dir
  @logger.info { "directory created - #{dir}" }
end

Start reliable-msg-agent

The configuration file is specified by commandline option.

$ reliable-msg-agent start -c /etc/reliable-msg-agent.conf
*** Starting ReliableMsg-Agent...
I, [2011-04-04T00:06:23.759875 #1804]  INFO -- : *** reliable-msg agent service starting...
I, [2011-04-04T00:06:23.759875 #1804]  INFO -- : --- starting workers.
I, [2011-04-04T00:06:23.783875 #1804]  INFO -- : *** reliable-msg agent service started.

Push message to reliable-msg queue.

The message “foo” and “bar” are push to queue of reliable-msg.

$ irb -rubygems -rreliable-msg
irb(main):001:0> ReliableMsg::Queue.new("queue.agent").put("foo")
 => "f19aadd0-4032-012e-f635-000ae47391e2"
irb(main):002:0> ReliableMsg::Queue.new("queue.agent").put("bar")
 => "f3c33320-4032-012e-f635-000ae47391e2"
irb(main):003:0> exit
$

The console that executes reliable-msg-agent is seen.

The message is acquired from reliable-msg, and directory was made.

$ reliable-msg-agent start -c /etc/reliable-msg-agent.conf
*** Starting ReliableMsg-Agent...
I, [2011-04-04T00:06:23.759875 #1804]  INFO -- : *** reliable-msg agent service starting...
I, [2011-04-04T00:06:23.759875 #1804]  INFO -- : --- starting workers.
I, [2011-04-04T00:06:23.783875 #1804]  INFO -- : *** reliable-msg agent service started.
I, [2011-04-04T00:14:07.921875 #1804]  INFO -- : message fetched - <f19aadd0-4032-012e-f635-000ae47391e2>
I, [2011-04-04T00:14:07.936875 #1804]  INFO -- : directory created - /tmp/foo
I, [2011-04-04T00:14:11.102875 #1804]  INFO -- : message fetched - <f3c33320-4032-012e-f635-000ae47391e2>
I, [2011-04-04T00:14:11.106875 #1804]  INFO -- : directory created - /tmp/bar

$ ls -l /tmp/{foo,bar}
/tmp/bar:
total 0

/tmp/foo:
total 0

Reliable-msg-agent commands

$ reliable-msg-agent
reliable-msg-agent available commands:
        stop
        start

start

$ reliable-msg-agent start --help
Usage: reliable-msg-agent start [options]
    -v, --verbose                    Verbose output
    -d, --daemon                     Daemon mode
    -u, --user=USER                  Effective user name
    -g, --group=GROUP                Effective group name
    -c, --conf=CONFFILE              Config file
    -l, --log=LOGFILE                Log file (only for the daemon mode)
    -p, --pid=PIDFILE                PID file (only for the daemon mode)
    -h, --help                       Show this message
        --version                    Show version

• -v, –verbose verbose output.

• -d, –daemon daemon mode.

• -u, –user effective user name (The authority of seteuid is necessary.)

• -g, –group effective group name (The authority of setegid is necessary.)

• -c, –conf=CONFFILE path for config file. default is {GEM_INSTALL_DIR}/resources/agent.conf

• -l, –log=LOGFILE path for log file. default is /var/reliable-msg-agent/agent.log (only for the daemon mode)

• -p, –pid=PIDFILE path for pid file. default is /var/reliable-msg-agent/agent.pid (only for the daemon mode)

• -h, –help show this message.

• –version show version.

stop

$ reliable-msg-agent stop --help
Usage: reliable-msg-agent stop [options]
    -v, --verbose                    Verbose output
    -p, --pid=PIDFILE                PID file
    -h, --help                       Show this message
        --version                    Show version

• -v, –verbose verbose output.

• -p, –pid=PIDFILE path for pid file. default is /var/reliable-msg-agent/agent.pid

• -h, –help show this message.

• –version show version.