NAME
   Luka - Exception handling and reporting framework

SYNOPSIS
       use Error qw(:try);
       use Luka;

   try {

           $ftp->login("someuser", "somepass") ||
               throw Luka::Exception::External
                   ( error => $ftp->message . $@, id => "login",
                     context => "FTP error: couldn't login", severity => 3,
                     args => "user=someuser,pass=somepass" );

   } catch Luka::Exception with {

           my $e = shift;
           $e->report;
           return 17;

        } catch Error with {

           my $e = shift;
           $e->report;
           return 18;

        };

DESCRIPTION
   Luka is an exception handling and reporting framework. It's useful to
   look at it as an event handling framework.

   It comes from operational understanding of networks.

   Scenario that Luka is addressing is following: on a network with
   multiple hosts running multiple applications, it is very difficult to
   track operational status of all the functionality that those
   applications and hosts are meant to deliver. In order to make it easier,
   we decided to specify the error handling and reporting data model that
   each component delivering functionality has to conform to. What is a
   component? In most cases, it is a script, often run from cronjob, in
   some cases it is a class in an application. In all cases, a component
   has to successfully complete a task on which functionality of an
   application, or entire network, relies on.

   It is common practice that programmers choose their way of handling
   errors and reporting. Luka is an attempt to standardize that process.
   Its primary goal is to make it easier for smaller number of people to
   keep larger number of applications and networks running.

   Policy on script error handling that Luka suggests:

   NO ERROR CODES are used, instead exceptions are thrown
       Already a common practice, especially in applications/components
       that are not small.

   Standard set of error english names is established (network connection
   error)
       As opposed to each network library, for example, having it's own way
       to report connection error.

   Page for each component (script/class) documenting relevant details
       Already a common practice. Luka suggests that link to page
       describing all possible errors, along with dependencies and
       schedules (for components that run regularly), should exist. It is
       part of the Luka event data model.

   EACH time an error occurs following MUST be attempted:

       1. Capture defined data set
       2. Log summary to to system log
       3. attempt delivery to end points

 Example config
     [global]
     debug=0
     single_char_error_code=E
     single_char_success_code=I
     doc_base=http://localhost/
     email_domain=lists.mydomain.org
     syslogopt=pid,nowait
     syslogfacility=daemon
     expected_ip=10.1.8

     [myscript.pl]
     on_success=Task completed
     doc=LukaTests
     about=this library does something useful
     from=root@localhost
     [email protected]
     nomail=0

 Example of error report
   On an error caught, in syslog:

     Feb 26 15:34:39 localhost myscript.pl[1298]: Luka initiating...
     Feb 26 15:34:39 localhost myscript.pl[1298]: Error at line 20: Net::FTP: Bad hostname 'bla.org' at myscript.pl line 324.
     Feb 26 15:34:39 localhost myscript.pl[1298]: Error report sent to [email protected],[email protected]

   Email headers:

     From: root@localhost
     To: [email protected]
     Cc: [email protected]
     Subject: [galeb][2006-2-26T15:34:42][E] Net::FTP: Bad hostname 'bla.org'

   Event (used verbatim in email body):

     this library does something useful

     http://localhost/LukaTests#ftp_object_creation

     host=galeb
     hosterr=
     ipaddr=10.1.8.18
     time=2006-2-26T15:34:42
     script=myscript.pl
     path=/home/toni/dev/cvs/perl/modules/luka
     line=245
     pid=1298
     severity=3
     context=FTP error: couldn't create object
     args=ftp.false
     id=ftp_object_creation
     error=Net::FTP: Bad hostname 'bla.org'

     Trace begun at myscript.pl line 245
     main::__ANON__ at /usr/local/share/perl/5.8.7/Error.pm line 372
     eval {...} at /usr/local/share/perl/5.8.7/Error.pm line 371
     Error::subs::try at myscript.pl line 255
     main::ftp_luka_catch at myscript.pl line 123
     main::__ANON__ at /usr/local/share/perl/5.8.7/Test/Exception.pm line 281
     eval {...} at /usr/local/share/perl/5.8.7/Test/Exception.pm line 281
     Test::Exception::lives_and at myscript.pl line 124

 Example of success report
   On a captured report, in syslog:

     Feb 26 15:34:22 localhost myscript.pl[1273]: Luka initiating...
     Feb 26 15:34:22 localhost myscript.pl[1273]: Success report sent to [email protected],[email protected]

   Email headers:

     From: root@localhost
     To: [email protected]
     Cc: [email protected]
     Subject: [galeb][2006-2-26T15:34:22][I] Task completed

   Event (used verbatim in email body):

     this library does something useful

     http://localhost/LukaTests

     host=galeb
     hosterr=
     ipaddr=10.1.8.18
     time=2006-2-26T15:34:22
     script=myscript.pl
     pid=1273

LUKA EVENT DATA MODEL
 Structure
     ABOUT COMPONENT
     \n
     DOC
     \n
     attribute=value
     attribute=value
     attribute=value
     attribute=attribute=value,attribute=value
     attribute=value
     \n
     \n
     STACKTRACE

 Fields
       ABOUT COMPONENT Comes from config file component section.

       DOC Location of the documentation. Can be URL, or some other
       protocol address. Can be specific to the error reported, or
       component general. Comes from config file component section.

       host - Name of the host where the event originates from. Collected.

       hosterr - Name of the services that Luka couldn't use as expected on
       the host. Collected. The only possible value is, at the moment,
       *syslogd*.

       ipaddr - IP address of the host. Collected. When multiple IPs
       present (most cases), regular expression matching one from the
       configuration file field "expected_ip" will be chosen.

       time - Timestamp, conforming to RFC3339 "Date and Time on the
       Internet: Timestamps", see <http://www.ietf.org/rfc/rfc3339.txt>.
       Example: "2006-2-26T15:34:42". Constructed out of host time.

       script - Name of the component that generated event. Collected.

       pid - Process ID of the component that generated the event.
       Collected from the host.

       path - Path to the component that generated event. Collected. Error
       event only.

       line - Line number where event generation occurred. Collected. Error
       event only. Error event only.

       severity - Severity level of the event (ambiguous, see TODO
       section). Supplied by the programmer at the location of event
       creation. Error event only.

       context - Descriptive text, context of the event. Specific to the
       functionality that components performs from the user perspective,
       rather than from the strictly technical perspective of programming
       libraries. Supplied by the programmer at the location of event
       creation. Error event only.

       args - Arguments relevant for the event generated (passed to the
       function, object). Supplied by the programmer at the location of
       event creation. Error event only.

       id - ID of the event. Supplied by the programmer at the location of
       event creation. Matches the documentation for the component. Error
       event only.

       error - Technical text of the error. Supplied by the programmer at
       the location of event creation. Supplement to the "context" field,
       from the technical perspective, can contain error text returned by
       used programming library. Error event only.

METHODS
 report
   Luka report to syslog what happens by default.

     Aug 26 11:27:49 localhost myscript.pl[1038]: Error at line 46: Net::FTP: Bad hostname
     'ftp.bla.bla' at myscript.pl line 80.

     Aug 26 11:27:49 localhost myscript.pl[1038]: Error report sent to [email protected]

 report_success( $message )
   If the $message is not supplied, value of the field "on_success" from
   the component section of Luka configuration file will be used.

DIAGNOSTICS
   "Luka system not functional for '%s' script. Couldn't read its section
   '%s' in config file '%s'"
       Throws Luka::Exception::Program exception. Luka can not deliver
       event if section for given script is missing in given config.
       Sections are by default named by the script name.

   "Luka system disabled. Couldn't read its config file '%s': %s"
       Throws Luka::Exception::Program exception. Luka can not do anything
       if its config file is missing or can not be parsed. However, if
       syslogd is running, it will place a warning in syslog:

         Feb 26 12:26:59 localhost Luka::Conf[30438]: Luka system disabled. Couldn't read its config file 'bla.txt':
         Failed to open bla.txt: No such file or directory at lib/Luka/Conf.pm line 63

   "Couldn't report by email to:%s;cc:%s;from:%s"
       Throws Luka::Exception::External. If MTA is not running, or if Luka
       can not connect to it, stdout will receive:

         ERROR: Can't connect to localhost:25
         Couldn't report by email to:test@localhost;cc:toni@localhost;from:root@localhost

       In the syslog, warning will be:

         Feb 26 13:42:08 localhost myscript.pl[3071]: Couldn't report by email: to: [email protected],
         cc: [email protected], from: root@localhost

         Feb 26 13:42:08 localhost myscript.pl[3071]: Mail system reported: ERROR: Can't connect to localhost:25

CONFIGURATION
 global section
   Single section, applies to the host on which Luka runs.

     [global]
     debug=0
     single_char_error_code=E
     single_char_success_code=I
     doc_base=http://localhost/
     email_domain=lists.mydomain.org
     syslogopt=pid,nowait
     syslogfacility=daemon
     expected_ip=10.1.8

   Fields:

       debug - Turns debugging mode on when set to 1.

       single_char_error_code - Delivery field. Single character error
       code. Default is "E". In email delivery, part of header SUBJECT
       field.

       single_char_success_code - Delivery field. Single character success
       code. Default is "I". In email delivery, part of header SUBJECT
       field.

       doc_base - Event field. Base part of the DOC field in the event data
       model.

       email_domain Delivery field. Email. Domain part of the header TO
       field.

       syslogopt *$logopt* options passed to Sys::Syslog's *openlog*
       function

       syslogfacility *$facility* option passed to Sys::Syslog's *openlog*
       function

       expected_ip Event field. See above IPADDR field in the event data
       model. Luka discovers IPs on the host. Since multiple IPs are
       present in most cases, regular expression matching one from this
       configuration file field *expected_ip* will be selected. This would
       be a drawback on a host with many interfaces, and solution with
       fixed IP would be a lot more efficient in that case.

 component sections
   One or more sections, applies to components programmed to use Luka.

     [myscript.pl]
     on_success=Task completed
     doc=LukaTests
     about=this library does something useful
     from=root@localhost
     [email protected]
     nomail=0

   Fields:

       on_success - Delivery field. In email delivery, part of header
       SUBJECT field.

       doc - Event field. Component part of the DOC field in the event data
       model.

       about - Event field. See above COMPONENT field in the event data
       model.

       from - Delivery field. Email. Header FROM field.

       cc - Delivery field. Email. Header CC field.

       nomail - If set to 1, event will not be delivered via email.

DEPENDENCIES
   *   Error - implementation of try/catch syntax

   *   Exception::Class - easy definition of hierarchy of exception classes

   *   Config::IniFiles - config file handling

   *   Sys::Syslog - writing to syslog

   *   Sys::Hostname - determining hostname

   *   Sys::Hostname::Long - determining hostname

   *   Mail::SendEasy - sending reports by email

   *   Class::Std - inside/out classes builder

INCOMPATIBILITIES
   Mod-perl, due to use of Class::Std. I wasn't aware of Class::Std
   limitations at the time of writing Luka. There are other implementations
   of inside-out classes on CPAN that should be used as replacements in of
   next releases of Luka. At the moment, best candidate seems to be
   Object::InsideOut.

BUGS AND LIMITATIONS
   Please report any bugs or feature requests to "[email protected]", or
   through the web interface at <http://rt.cpan.org>.

TODO
   mod-perl compatibility
       Migration from Class::Std to Object::InsideOut, or some other
       inside-out class.

   severity definitions
       Severity needs defining, according to appropriate existing standard.

   date-time format, timezone missing
       Timezone needs adding to the date-time (RFC 3339) format.

   report delivery mechanism abstraction
       Reporting is also event delivery, and event delivery can be done in
       many ways. Currently, email is hardcoded as a delivery mechanism.
       Instead, reporting delivery has to be configurable. It could be done
       via dynamic loading (from a value in the config) of class
       implementing desired mechanism.

   reporting to syslog config setting
       It is default now that Luka method "report" uses syslog for short
       reporting. It should be made optional, in global, and script,
       setting. Global config setting should be default; individual script
       setting should override it.

   event delivery on missing component section
       When a section for component is missing in the config file,
       exception is thrown (see DIAGNOSTICS above). Instead, event should
       still be delivered, as long as relevant details about the
       destination of delivery are in the global part of the Luka
       configuration file.

   improve documentation
       Documentation needs careful re-reading and improving. Any comments
       on this especially appreciated.

ACKNOWLEDGEMENTS
   Ideas for underlining premises of Luka came out of discussions with Bill
   Hulley.

AUTHOR
   Toni Prug <[email protected]>

COPYRIGHT
   Copyright (c) 2006. Toni Prug. All rights reserved.

   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

   See <http://www.gnu.org/licenses/gpl.html>

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