Provided by: libnetsds-perl_1.301-3_all 
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.
• start() - start time hook
• process() - process iteration hook
• 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,
);
• 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.
• 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"
• 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.
• debug - 1 for debugging flag (default: no)
• daemon - 1 for daemon mode (default: no)
• verbose - 1 for verbose mode (default: no)
• use_pidfile - 1 to use PID files (default: no)
• pid_dir - path to PID files catalog (default: '/var/run/NetSDS')
• 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.
• infinite - 1 for inifinite loop (default: yes)
• 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.
• --conf - path to config file
• --[no]debug - set debug mode
• --[no]daemon - set daemon/foreground mode
• --[no]verbose - set verbosity mode
• --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