= Daemons Version 1.0.3

(See Releases for release-specific information)

== What is Daemons?

Daemons provides an easy way to wrap existing ruby scripts (for example a self-written server) 
to be <i>run as a daemon</i> and to be <i>controlled by simple start/stop/restart commands</i>.

If you want, you can also use daemons to <i>run blocks of ruby code in a daemon process</i> and to control
these processes from the main application.

Besides this basic functionality, daemons offers many advanced features like <i>exception backtracing</i> 
and logging (in case your ruby script crashes) and <i>monitoring</i> and automatic restarting of your processes
if they crash.

Daemons includes the <tt>daemonize.rb</tt> script written by <i>Travis Whitton</i> to do the daemonization
process.

== Basic Usage

You can use Daemons in four differet ways:

=== 1. Create wrapper scripts for your server scripts or applications

Layout: suppose you have your self-written server <tt>myserver.rb</tt>:

  # this is myserver.rb
  # it does nothing really useful at the moment
  
  loop do
    sleep(5)
  end
  
To use <tt>myserver.rb</tt> in a production environment, you need to be able to
run <tt>myserver.rb</tt> in the _background_ (this means detach it from the console, fork it
in the background, release any directories and file descriptors).

Just create <tt>myserver_control.rb</tt> like this:

  # this is myserver_control.rb
  
  require 'rubygems'        # if you use RubyGems
  require 'daemons'
  
  Daemons.run('myserver.rb')
  
And use it like this from the console:

  $ ruby myserver_control.rb start
      (myserver.rb is now running in the background)
  $ ruby myserver_control.rb restart
      (...)
  $ ruby myserver_control.rb stop
  
For testing purposes you can even run <tt>myserver.rb</tt> <i>without forking</i> in the background:

  $ ruby myserver_control.rb run

An additional nice feature of Daemons is that you can pass <i>additional arguments</i> to the script that 
should be daemonized by seperating them by two _hyphens_:
  
  $ ruby myserver_control.rb start -- --file=anyfile --a_switch another_argument
  

=== 2. Create wrapper scripts that include your server procs

Layout: suppose you have some code you want to run in the background and control that background process
from a script:

  # this is your code
  # it does nothing really useful at the moment
  
  loop do
    sleep(5)
  end
  
To run this code as a daemon create <tt>myproc_control.rb</tt> like this and include your code:

  # this is myproc_control.rb
  
  require 'rubygems'        # if you use RubyGems
  require 'daemons'
  
  Daemons.run_proc('myproc.rb') do
    loop do
      sleep(5)
    end
  end
  
And use it like this from the console:

  $ ruby myproc_control.rb start
      (myproc.rb is now running in the background)
  $ ruby myproc_control.rb restart
      (...)
  $ ruby myproc_control.rb stop
  
For testing purposes you can even run <tt>myproc.rb</tt> <i>without forking</i> in the background:

  $ ruby myproc_control.rb run
  
=== 3. Control a bunch of daemons from another application

Layout: you have an application <tt>my_app.rb</tt> that wants to run a bunch of 
server tasks as daemon processes.

  # this is my_app.rb
  
  require 'rubygems'        # if you use RubyGems
  require 'daemons'
  
  task1 = Daemons.call(:multiple => true) do
    # first server task
    
    loop {
      conn = accept_conn()
      serve(conn)
    }
  end
  
  task2 = Daemons.call do
    # second server task
    
    loop {
      something_different()
    }
  end
  
  # the parent process continues to run
  
  # we can even control our tasks, for example stop them
  task1.stop
  task2.stop
  
  exit
  
=== 4. Daemonize the currently running process

Layout: you have an application <tt>my_daemon.rb</tt> that wants to run as a daemon
(but without the ability to be controlled by daemons via start/stop commands)

  # this is my_daemons.rb
  
  require 'rubygems'        # if you use RubyGems
  require 'daemons'
  
  # Initialize the app while we're not a daemon
  init()
  
  # Become a daemon
  Daemons.daemonize
  
  # The server loop
  loop {
    conn = accept_conn()
    serve(conn)
  }

  
<b>For further documentation, refer to the module documentation of Daemons.</b>

  
== Download and Installation

*Download*: just go to http://rubyforge.org/projects/daemons/

Installation *with* RubyGems:
  $ su
  # gem install daemons
  
Installation *without* RubyGems:
  $ tar xfz daemons-x.x.x.tar.gz
  $ cd daemons-x.x.x
  $ su
  # ruby setup.rb
  
== Documentation

For further documentation, refer to the module documentation of Daemons (click on Daemons).

The RDoc documentation is also online at http://daemons.rubyforge.org


== Author

Written in 2005 by Thomas Uehlinger <mailto:th.uehlinger@gmx.ch>.
Homepage: http://physiker.ch

== License

The Daemons script is copywrited free software by Thomas Uehlinger
<mailto:th.uehlinger@gmx.ch>. You can redistribute it under the terms specified in
the COPYING file of the Ruby distribution.


== Feedback and other resources

At http://rubyforge.org/projects/daemons.
