NetSDS::App(3pm)					User Contributed Perl Documentation					  NetSDS::App(3pm)

NAME

       NetSDS::App - common application superclass

SYNOPSIS

	       #!/usr/bin/env perl

	       use 5.8.0;
	       use warnings;
	       use strict;

	       MyApp->run(
		       conf_file => '/etc/NetSDS/myapp.conf', # default place for config search
		       daemon => 1,	 # run in daemon mode
		       use_pidfile => 1, # write PID file to avoid double processing
		       verbose => 0,	 # no verbosity
	       );

	       1;

	       # Application logic here
	       package MyApp;

	       use base 'NetSDS::App';

	       # Startup hook
	       sub start {
		       my ($self) = @_;

		       # Use configuration
		       $self->{listen_port} = $self->conf->{listen_port};

		       # Use logging subsystem
		       $self->log("info", "Application successfully started with PID=".$self->pid);
	       }

	       # Main processing hook
	       sub process {
		       my ($self) = @_;
		       print "Hello!";

		       # Use verbose output
		       $self->speak("Trying to be more verbose");

	       }

DESCRIPTION

       "NetSDS::App" is a base class for NetSDS applications.  It implements common functionality including the following:

	       * initialization
	       * configuration file processing
	       * command line parameters processing
	       * application workflow
	       * daemonization
	       * PID file processing
	       * logging
	       * event detail records writing
	       * default signal handling

       New application should be inherited from "NetSDS::App" class directly or via child classes for more specific tasks like CGI, AGI, SMPP and
       other.

       Common application workflow is described on this diagram:

	       App->run(%params)
		  |
	       initialize()
		  |
		  ----------
		  |	   |
	       start()	   |
		  |	   |
	       process()   --- main_loop()
		  |	   |
	       stop()	   |
		  |	   |
		  ----------
		  |
	       finalize()

       When application is starting "initialize()" method is invoked first.  It provides common start time functionality like CLI parameters
       processing, daemonization, reading configuration.

       "initialize()" method may be overwritten in more specific frameworks to change default behaviour of some application types.

       Then "main_loop()" method invoked to process main application logic.  This method provides three redefinable hooks: "start()", "process()"
       and "stop()".  Theese hooks should be overwritten to implement necessary logic.

       o   start() - start time hook

       o   process() - process iteration hook

       o   stop() - finish time hook

       Depending on "infinite" flag main_loop() may call process() hook in infinite loop or only once.

       "main_loop()" workflow may be redefined in inherited framework to implement some other process flow logic.

       On the last step "finalize()" method is invoked to make necessary finalization actions on framework level.

STARTUP PARAMETERS

       Application class may be provided with a number of parameters that allows to manage application behaviour.  For example it may be a
       configuration file, daemonization mode or debugging flag.

       Such parameters are passed to run() method as hash:

	       MyApp->run(
		       has_conf => 1,
		       conf_file => '/etc/sample/file.conf',
		       daemon => 1,
		       use_pidfile => 1,
	       );

       o   has_conf - 1 if configuration file is required (default: yes)

	   Mostly our applications requires configuration files but some of them doesn't require any configuration (e.g. small utilities, etc).
	   Set "has_conf" parameter to 0 to avoid search of configuration file.

       o   conf_file - default path to configuration file (default: autodetect)

	   This parameter allows to set explicitly path to configuration file.	By default it's determined from application name and is looking
	   like "/etc/NetSDS/{name}.conf"

       o   name - application name (default: autodetect)

	   This name is used for config and PID file names, logging.  By default it's automatically detected by executable script name.

       o   debug - 1 for debugging flag (default: no)

       o   daemon - 1 for daemon mode (default: no)

       o   verbose - 1 for verbose mode (default: no)

       o   use_pidfile - 1 to use PID files (default: no)

       o   pid_dir - path to PID files catalog (default: '/var/run/NetSDS')

       o   auto_features - 1 for auto features inclusion (default: no)

	   This parameter should be set to 1 if you plan to use automatically plugged application features. Read "PLUGGABLE APPLICATION FEATURES"
	   section below.

       o   infinite - 1 for inifinite loop (default: yes)

       o   edr_file - EDR (event detail records) file name (default: undef)

COMMAND LINE PARAMETERS

       Command line parameters may be passed to NetSDS application to override defaults.

       o   --conf - path to config file

       o   --[no]debug - set debug mode

       o   --[no]daemon - set daemon/foreground mode

       o   --[no]verbose - set verbosity mode

       o   --name - set application name

       These CLI options overrides "conf_file", "debug", "daemon", "verbose" and "name" default parameters that are passed in run() method.

       Examples:

	       # Debugging in foreground mode
	       ./application --config=/etc/myapp.conf --nodaemon --debug

	       # Set application name explicitly
	       ./application --name=myapp

CLASS API

       new([%params]) - class constructor
	   Constructor is usually invoked from "run()" class method.  It creates application object and set its initial properties from oarameters
	   passed as hash.

	   Standard parameters are:

		   * name - application name
		   * debug - set to 1 for debugging
		   * daemon - set to 1 for daemonization
		   * verbose - set to 1 for more verbosity
		   * use_pidfile - set to 1 for PID files processing
		   * pid_dir - path to PID files catalog
		   * conf_file - path to configuration file
		   * has_conf - set to 1 if configuration file is necessary
		   * auto_features - set to 1 for auto features inclusion
		   * infinite - set to 1 for inifinite loop

       run(%parameters) - application launcher
	   This method calls class constructor and then switch to "main_loop()" method.

	   All method parameters are transparently passed to application constructor.

		   #!/usr/bin/env perl

		   use 5.8.0;
		   use warnings;
		   use strict;

		   MyApp->run(
			   conf_file => '/etc/myapp.conf',
			   daemon => 1,
			   use_pidfile => 1,
		   );

		   1;

		   # **********************************
		   # Logic of application

		   package MyApp;
		   use base 'NetSDS::App';
		   1;

       name([$name]) - application name
	   This method is an accessor to application name allowing to retrieve this or set new one.

		   print "My name is " . $self->name;

       pid() - PID of application process
	   Read only access to process identifier (PID).

		   print "My PID is " . $self->pid;

       debug() - debugging flag
	   This method provides an accessor to debugging flag.	If application called with --debug option it will return TRUE value.

		   if ($self->debug) {
			   print "Debug info: " . $debug_data;
		   }

       verbose() - verbosity flag
	   This method provides an accessor to verbosity flag.

	   It may be used to increase application verbosity level if necessary.

		   if ($self->verbose) {
			   print "I'm working!";
		   };

	   NOTE: This flag is is for normal operations. If you need implement debug output or other development/testing functionality - use
	   debug() instead.

       logger() - accessor to logger
	   This method is accessor to logger (object of NetSDS::Logger class).

	   NOTE: There is no need to use this method directly in application. See "log()" method description to understand logging features.

       conf() - accessor to configuration
	   This method is accessor to application configuration represented as hash reference returned by NetSDS::Conf module.

	   Configuration sample:

		   ------------------------
		   content_dir /var/lib/content

		   <kannel>
			   send_url http://127.0.0.1:13013/
			   login netsds
			   passwd topsecret
		   </kannel>
		   ------------------------

	   Code sample:

		   # Retrieve configuration
		   my $content_dir = $self->conf->{content_dir};
		   my $kannel_url = $self->conf->{kannel}->{send_url};

       use_pidfile(BOOL) - PID file checking flag
	   Paramters: TRUE if PID file checking required

       pid_dir([$directory]) - PID files storage
	   Paramters: directory name

		   $app->pid_dir("/var/run");

       daemon(BOOL) - daemonization flag
	   Paramters: TRUE if application should be a daemon

		   if ($self->daemon()) {
			   $self->log("info", "Yeah! I'm daemon!");
		   };

       auto_features() - auto features flag
	   Automatic features inclusion allowed if TRUE.

       infinite([$bool]) - is application in infinite loop
	   Example:

		   # Switch to infinite loop mode
		   $app->infinite(1);

       edr_file([$file_name]) - accessor to EDR file name
	   Paramters: EDR file path

       initialize()
	   Common application initialization:

	   1. Reading config if necessary.

	   2. Daemonize application.

	   3. Check PID file for already running application instances.

	   4. Start logger.

	   5. Prepare default signal handlers.

       use_auto_features() - add features to application
	   This method implements automatic features inclusion by application configuration file (see "feature" sections).

       add_feature($name, $class, $config, %params) - add feature
	   Paramters: feature name, class name, parameters (optional)

	   Returns: feature object

		   $self->add_feature('kannel','NetSDS::Feature::Kannel', $self->conf->{feature}->{kannel});
		   $self->kannel->send(.....);

       finalize() - switch to finalization stage
	   This method called if we need to finish application.

       start() - user defined initialization hook
	   Abstract method for postinitialization procedures execution.

	   Arguments and return defined in inherited classes.  This method should be overwritten in exact application.

	   Remember that start() methhod is invoked after initialize()

       process() - main loop iteration hook
	   Abstract method for main loop iteration procedures execution.

	   Arguments and return defined in inherited classes.

	   This method should be overwritten in exact application.

       stop() - post processing hook
	   This method should be rewritten in target class to contain real post processing routines.

       main_loop() - main loop algorithm
	   This method provide default main loop alghorythm implementation and may be rewritten for alternative logic.

LOGGING AND ERROR HANDLING

       log($level, $message) - write message to log
	   This method provides ablity to write log messages to syslog.

	   Example:

		   $self->log("info", "New message arrived with id=$msg_id");

       error($message) - return error with logging
	   This method extends inherited method functionality with automatically logging this message to syslog.

	   Example:

		   if (!$dbh->ping) {
			   return $self->error("We have problem with DBMS");
		   }

       speak(@strs) - verbose output
	   Paramters: list of strings to be written as verbose output

	   This method implements verbose output to STDOUT.

		   $self->speak("Do something");

       edr($record [,$record..]) - write EDR
	   Paramters: list of EDR records to write

		   $app->edr({
			   event => "call",
			   status => "rejected",
		   });

       config_file($file_name) - determine full configuration file name

PLUGGABLE APPLICATION FEAUTURES

       To add more flexibility to application development "NetSDS::App" framework allows to add pluggable features.  Application feature is a
       class dynamically loaded into application using configuration file parameters.

       To use application features developer should do the following:

       * set auto_features run() parameter

       * create "feature" sections in application as described

       * create feature classes inherited from NetSDS::Feature

EXAMPLES

       See samples/app.pl

BUGS

       This module is a one bug itself :-)

SEE ALSO

       NetSDS, NetSDS::Class::Abstract, NetSDS::Logger

TODO

       Fix and cleanup!

AUTHOR

       Valentyn Solomko <val@pere.org.ua>

       Michael Bochkaryov <misha@rattler.kiev.ua>

LICENSE

       Copyright (C) 2008-2009 Net Style Ltd.

       This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by
       the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

       This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

       You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation,
       Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

perl v5.10.1							    2010-04-28							  NetSDS::App(3pm)