John Beppu > App-VW > App::VW

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NAME ^

App::VW - a deployment system for Squatting+Continuity web apps

SYNOPSIS ^

First, install the vw system:

  sudo vw install

Then, setup some apps for vw to manage:

  cd /path/to/squatting/app
  sudo vw setup App --port=5000 --cluster-size=1
  vi vw_harness.pl

Starting and stopping vw:

  sudo /etc/init.d/vw start
  sudo /etc/init.d/vw stop

Making vw start up at boot time (on Debian-derived systems):

  sudo update-rc.d vw defaults

Disabling vw from starting up at boot (on Debian-derived systems):

  sudo update-rc.d -f vw remove

Watching vw's syslog output (on Debian-derived systems):

  sudo tail -f /var/log/user.log

DESCRIPTION ^

camping : rv :: squatting : vw

vw is a system for deploying Squatting web apps using the Continuity backend. It's modeled after rv which was a system for deploying Camping applications during the Camping 1.5 era. (Unfortunately, I don't think it works for Camping 2.0.)

If you like the idea of starting up a cluster of web servers and putting them behind a reverse proxy (like nginx, perlbal, or Apache's mod_proxy_balancer), then vw might be the system for you.

Getting Started

The "SYNOPSIS" tells you most of what you need to know.

Running vw help will give you a list of subcommands.

You can also run vw help SUBCOMMAND to get more information on the various subcommands.

Example:

  vw help install
  vw help setup

FILES ^

/etc/init.d/vw

This is the init script for vw, and it gets installed when you run vw install. The following commands are supported.

start

Start the Squatting+Continuity apps as defined in /etc/vw/*.yml.

stop

Stop the Squatting+Continuity apps (via SIGINT).

restart

Stop and start the Squatting+Continuity apps.

reload

This command sends a SIGHUP to the vw-bus process, but the process hasn't been setup to respond to it yet, so it's currently a NO-OP.

/etc/vw/*.yml

These YAML files tell vw how to start up a Squatting application. The data in these YAML files are passed to the vw_harness.pl files in key/value form via @ARGV. (my %opts = @ARGV)

These files are created for you when you run vw setup, and here's how one might look like:

  ---
  app: Bavl
  cluster_size: 1
  dir: /www/towr.of.bavl.org
  port: 4010

The required fields are:

app

This is the module name of the Squatting app.

dir

This is the directory that the vw_harness.pl for this app is in. This directory should be writable because some pid files are written here. (In the future, we may write the pid files for the worker processes elsewhere.)

port

This is the port that the app should listen on for HTTP requests.

cluster_size

This is the number of processes to start for the app.

Note that if port is 2000 and cluster_size is 4, then 4 processes will be started up, and they'll handle ports 2000, 2001, 2002, and 2003.

It's up to you to make sure the ports on your system don't overlap!!!

Feel free to edit this file and even add more configuration variables if that would be helpful to you.

vw_harness.pl

This is the script that that actually starts up the Squatting::On::Continuity web server. This is also created for you when you run vw setup.

It gets the contents of the app's YAML file in @ARGV in key/value form. That means the vw_harness.pl scripts can conveniently get their YAML config via code like this:

  my %opts = @ARGV;

The script's job is to start up a server that loops forever. It DOES NOT have to fork or daemonize itself, because the vw system is already doing that for you.

Feel free to edit this script as much as you want. Any and all initialization for your web app can be done here.

REVELATION ^

Although vw was intended to be a system for deploying Squatting applications on top of Continuity, it can actually deploy any kind of server you want. If you wanted to deploy a pure Continuity app, it wouldn't be too hard to write a vw_harness.pl to do just that:

A vw_harness.pl for a Continuity App

  use strict;
  use warnings;
  use Continuity;
  my %opts = @ARGV;
  Continuity->new(
    port     => $opts{port}, 
    callback => sub { 
      my ($cr) = @_;
      $cr->print("Hello, World!");
    }
  )->loop;

A vw_harness.pl for haXe Video

The servers you start via vw don't even have to be written in Perl. For example, we could start haXe Video using a simple vw_harness.pl like this:

  use strict;
  use warnings;
  my %opts = @ARGV;
  open(STDOUT, ">>", "haxevideo.log");
  open(STDERR, ">>", "haxevideo.log");
  exec("neko server.n");

Creating a custom vw_harness.pl is the key.

BUGS ^

Currently, vw is only known to work on Debian and Debian-derivatives (like Ubuntu). By chance, it may also work on other Linux systems that use SysV init for starting daemons at boot up, but that's not guaranteed.

If you'd like to use App::VW with other Linux distros or other Unixes, send me an email, and we can work on adding support for your system.

SEE ALSO ^

Subcommands

App::VW::Help, App::VW::Install, App::VW::Setup, App::VW::Restart, App::VW::Start, App::VW::Stop

Utilities

vw, vw-bus

Related Perl Modules

Squatting, Squatting::On::Continuity, Continuity, App::CLI

Related Ruby Code

http://code.whytheluckystiff.net/camping/

http://github.com/fauna/rv/tree/master

AUTHOR ^

John BEPPU <beppu@cpan.org>

COPYRIGHT ^

Copyright (c) 2008 John BEPPU <beppu@cpan.org>.

The "MIT" License

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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