Revision history for Perl extension Helios.
2.60  Mon Nov 06 00:00:00 2012
	-Significant changes to Helios database connection handling, 
	 including a specialized Data::ObjectDriver class and TheSchwartz 
	 extensions.  Helios now aggressively caches database connections
	 at the DBI layer and uses DBI features to properly handle 
	 database connect/disconnect between daemon and worker processes. 
	 These improvements result in significant performance increases, 
	 especially when using Oracle as a collective database.  One 
	 user's application experienced job throughput increases of ~70%. 
	 MySQL collectives should also experience speed increases and 
	 a reduced number of open connections.
	-NEW Helios::Config modular configuration API.  Similar to 
	 Helios::Job and Helios::Logger, Helios::Config defines the basic 
	 Helios configuration API while also serving as a base class to 
	 build custom configuration modules for Helios applications.  To 
	 define a custom configuration API for a Helios application, 
	 specify a ConfigClass() method in your Helios::Service subclass. 
	 Auxiliary application pieces such as scripts and cronjobs can use 
	 Helios::Config to get the application's configuration without 
	 needing to instantiate the application class and calling the 
	 prep() method as in the past.  Helios::Config makes the Helios 
	 configuration API more robust, modular, and flexible.  See the 
	 Helios::Config POD for more details.
	 NOTE: Helios::Service->getConfigFrom*() methods are now 
	 deprecated in favor of Helios::Config->parseConfig().  The prep()
	 method uses Helios::Config and will continue to be supported.
	-NEW Helios exception class for configuration errors:  
	-NEW WORKER_MAX_TTL_WAIT_INTERVAL parameter to fine-tune use of 
	 WORKER_MAX_TTL with specific applications.
	-NEW WORKER_BLITZ_FACTOR configuration parameter to launch 
	 more workers sooner.
	-NEW configuration parameter documentation.  All Helios 
	 out-of-box configuration parameters are now defined in a section 
	 of the Helios::Config POD.  For more information about the new 
	 configuration parameters or any others, check the Helios::Config 
	-Helios::Service->dbConnect() has been updated to work with the 
	 new database connection caching scheme and to better support 
	 DBI options.
	-Bundle::Helios::Generic has been changed to Bundle::Helios and 
	 can be used to install Helios prerequisite modules with generic 
	 Perl installs.  Bundle::Helios::RedHat was dropped in 2.41.  See 
	 the INSTALL.* files in the main distribution directory to 
	 determine the right type of install method for your environment.
	-Improved module loading code.
	-Removal of most instances of Error module's try {} catch {} 
	 blocks in favor of Perl generic eval {} or do {}.
	-More tests.
	-Updated INSTALL.* files for generic Perl and CPAN installs and 
	 Red Hat/CentOS 6.x.  BSD, Mac OS X, and other *nix should use the 
	 generic install instructions.  (Debian and Ubuntu based 
	 instructions continue to be the quickest and easiest.  Thank you 
	 Debian for your excellent Perl and CPAN packaging!)
2.41  Sun Jun 03 22:00:00 2012
	-Official Oracle support!  DDL for a Helios Oracle schema is in 
	 'sql/helios_schema_oracle.sql'.  Please note: 
	 1) you will need to adjust the Oracle schema to fit your 
	    environment (especially in regards to security and tablespaces)
	 2) while the Helios core supports Oracle, the Helios::Panoptes 
	    web admin interface still only supports MySQL (Panoptes 
	    support for Oracle is being worked on) 
	-Helios::Service and Helios::Job: added deferredJob() and 
	 deferred() methods to defer processing of a job even though it 
	 was available in the job queue.  These methods (for now) simply 
	 expose the declined() feature added in TheSchwartz 1.10; no Helios
	 job history is recorded for a deferred job.  Existing Helios 
	 users will need to upgrade their TheSchwartz library to 1.10 to 
	 use this feature.
	-Helios::Logger & Helios::Logger::Internal:  moved driver 
	 creation to base Helios::Logger class so (if necessary) any 
	 loggers can get a Data::ObjectDriver to the collective database
	-Helios::Service & Helios::Logger:  refactored getDriver() into 
	 initDriver() and getDriver() to eventually allow caching of 
	 Data::ObjectDriver objects.  Anything needing an ObjectDriver to 
	 the collective database should just continue to call getDriver() 
	 and everything will work fine. calls the service class prep() method on startup 
	 rather than getConfigFromIni() and getConfigFromDb() separately.
	 This ensures proper setup of the loggers and Data::ObjectDriver 
	 db connection. changed startup message so perl doesn't carp a warning 
	 if the service class doesn't have a $VERSION defined. added registration_interval as a configuration 
	 parameter (previously it was hard-coded to 300 seconds in  The "registration_interval" parameter is the amount 
	 of time (in secs) between service daemon "collective check-ins" 
	 (when a service daemon records its current status in the 
	 HELIOS_WORKER_REGISTRY_TB table).  This table is used to create 
	 the Helios::Panoptes Collective Admin page, and is also useful 
	 for system monitoring and statistics. set new defaults for zero_sleep_interval (10) and 
	 registration_interval (60).  These new defaults should make 
	 Helios more responsive in low load situations and generally work 
	 better for more users out-of-the-box.  (The old defaults geared 
	 Helios more for large volumes of long-running jobs on heavily
	 loaded databases.  The new defaults should work for a better 
	 range of small- to mid-sized loads.)  If these new defaults 
	 create too much traffic for your database, you can set new 
	 larger values in your helios.ini file to decrease database 
	 traffic. changes to prevent a worker from transmuting to a new 
	 service daemon (caused by database instability during transition 
	 between, TheSchwartz->work(), and Helios::Service->work() 
	-updated tests  fixed example in POD
	-Removed Bundle::Helios::RedHat.  Ultimately, it didn't work any 
	 better (or worse) than using 'install Helios' command with the 
	 CPAN shell.  Bundle::Helios::Generic seems to work well on other 
	 platforms, however.  If you wish to use Helios with RHEL/CentOS 
	 5.x or earlier, it is recommended you install a more recent 
	 version of Perl than 5.8.8 for ease of installation reasons.  
2.40  Sun Jan 22 22:30:00 2012
	-NEW Extensible logging subsystem (Helios::Logger) 
	-NEW Helios::Error::BaseError exception class; acts as parent for
	 entire Helios::Error:: hierarchy
	-NEW Helios::Service->metarun() method to modularize metajob 
	 handling and provide for extensible metajob support 
	-NEW service run() and metarun() methods now run in an eval 
	 block as a process safety measure to catch uncaught exceptions.
	-NEW MP3IndexerService example application including in eg/
	 directory (StubService also rewritten for clarity)
	-REVISED Helios::Service->work() method no longer pays attention 
	 to return value of run() method (this feature was under-
	 documented, misunderstood, and caused problems with eval {} and 
	 Try::Tiny exception handling
	-REWRITTEN CGI script; supports sending XML stream 
	 in addition to form encoding, no longer dependent on 
	-REWRITTEN Helios::TestService; more modern Perl and easier to 
	-REWRITTEN install instructions, including specific instructions 
	 for Red Hat- and Ubuntu-based systems, and including CPAN install 
     bundles (still experimental)
    -REWRITTEN Helios::Tutorial 
    -Helios::Service:  fixed MaxRetries() and RetryInterval() retry 
     job methods
	-Helios::Job:  changed failed() and failedNoRetry() to limit the 
	 char length of the error recorded to 254 chars.  That's one less 
	 than the default size of the db field in the ERROR table, so it 
	 should prevent long errors like stack traces from unexpectedly 
	 blowing up worker processes and potentially losing jobs.
	-Revised dependencies:
	 DBI 1.52 (shipped with RHEL/CentOS 5)
	 XML::Simple 2.14 (shipped with RHEL/CentOS 5)
	 Removed XML::SAX dependency (unnecessary)
	 Removed XML::Namespace dependency (unnecessary)
	 Removed XML::Parser dependency (unnecessary)
	-Removed deprecated classes, methods, and other files:
	 Helios::Service->parseArgXML() (deprecated since 2.00)
	 Helios::Worker (deprecated since 2.00)
	-Updated copyright notices
	-Switch to "Linux-style" versioning: 
	 odd minor version == development version
	 even minor version == stable version
	 second minor number == patch level
	 (we're still also using Perl-style _ for devel versions too)
2.23  Fri Sep 10 12:22:00 2010
	-Helios::Job: fixed bug where getArgXML() returned undef if job
	 object was vivified from job queue
2.22  Thu May 21 11:30:00 2009
	-Helios::Service: fixed a bug in getFuncidFromDb() that caused 
	 services to fail to load properly if there was no entry for them 
	 in FUNCMAP table. Several revisions to make it a more robust daemon. Now
	 honors TERM signal; 'kill <pid>' from a shell will attempt to 
	 safely shut down workers and daemon process w/o using Panoptes
	-Documentation updates
2.21  Thu May 14 17:00:00 2009
	-added set/getJob() accessors to facilitate access to current 
	 Helios::Job object from methods other than run()
2.20  Tue Apr 28 18:00:00 2009
    -various tweaks for cross-platform compatibility
    -documentation additions/corrections
    -added Helios::LogEntry::Levels to remove dependencies on 
     Sys::Syslog Cleaned up messages to console after daemonize + Helios::Service: added support for WORKER_MAX_TTL 
	 config param
    -Helios::Service: added JobClass() allow extensible Helios::Job 
    -Helios::Service: added MaxRetries() and RetryInterval() to replace
     TheSchwartz's max_retries() and retry_interval() (this is not an 
     abitrary change; it's to allow for extensions at the Helios layer 
     in the future)
    -Helios::Service: added default run() method for class completeness
     (it throws a Helios::Error::FatalNoRetry error because you forgot 
     to implement a run() method)
    -Helios::Service: removed logging to syslogd to eliminate 
     Sys::Syslog dependency (see HeliosX::ExtLoggerService)
    -Helios::Service: added set/getFuncid(), getFuncidFromDb() and 
     changed jobWaiting() to use them.  This eliminates an unnecessary 
     database query previously done every time jobsWaiting() was called
    -Helios::Service: added support for log_priority_threshold config 
    -Helios::Job: added getFailures() to access the number of times a 
     job has previously failed
2.00  Fri Aug 01 02:00:00 2008
	-First public production release (same as 1.90_26 w/more documentation)
1.90_26 Thu Jun 26 11:30:00 2008
	-Helios 2.0 RC1
	-NEW Helios 2.0 API
	 Helios::TestService added PID check to prevent 2 instances of a service 
	 running on the same server added --clear-halt option to clear Worker Admin HALTs 
	 at the cmd line
	-helios.sql: new helios_worker_registry_tb.start_time field for 
	 uptime stats,, use new 
	 2.0 API
	-eg/Stub/ for example of new 2.0 API service class
	-new tests to test both 1.x and 2.x API	
1.19_07 Thu May 29 14:00:00 2008
	-added (for version checking & documentation)
	-added Helios::Job (for eventual refactoring)
	-added Helios::Test (for system testing)
1.19_06 Wed May 28 12:00:00 2008
	-added LICENSE file that was left out
	-add utility to clean log, job history
	-added eg/Stub/ as a worker class stub example
1.19  Mon May 19 12:00:00 2008
	-First public release