NAME
Bio::DB::DBI::TransactionListener - a simple transaction listener
SYNOPSIS
# see method sectionDESCRIPTION
This object is the contract and at the same time a simple (neutral) implementation of a transaction listener.
Transaction listeners are notified before and after commit and rollback on transactions as represented by a Bio::DB::DBI::Transaction objects.
Note that this is a very loose contract in the sense that it is not enforced. Therefore it serves more as a guideline of what you *can* do rather than what you have to do.
You may currently choose between 3 different options on how to listen to transactions:
- write your own transaction listener that inherits from this
class and overrides methods as suitable, then use your class to
add listeners to Transactions
- let your adaptor or persistent object module inherit from this
class and thereby make it a listener-compliant object that you
can then use to register with Transactions
- register any object with Transaction that implements at least
one of the methods defined here (if it implements none then
what's the point?). Transaction will only call the methods
defined here if the listener actually implements them.FEEDBACK
Mailing Lists
User feedback is an integral part of the evolution of this and other Bioperl modules. Send your comments and suggestions preferably to the Bioperl mailing list. Your participation is much appreciated.
bioperl-l@bioperl.org - General discussion
http://bioperl.org/wiki/Mailing_lists - About the mailing listsSupport
Please direct usage questions or support issues to the mailing list:
bioperl-l@bioperl.org
rather than to the module maintainer directly. Many experienced and reponsive experts will be able look at the problem and quickly address it. Please include a thorough description of the problem with code and data examples if at all possible.
Reporting Bugs
Report bugs to the Bioperl bug tracking system to help us keep track of the bugs and their resolution. Bug reports can be submitted via the web:
http://redmine.open-bio.org/projects/bioperl/AUTHOR - Hilmar Lapp
Email hlapp at gmx.net
Describe contact details here
CONTRIBUTORS
Additional contributors names and emails here
APPENDIX
The rest of the documentation details each of the object methods. Internal methods are usually preceded with a _
new
Title : new
Usage : my $obj = Bio::DB::DBI::TransactionListener->new();
Function: Builds a new Bio::DB::DBI::TransactionListener object
Returns : an instance of Bio::DB::DBI::TransactionListener
Args :register_sub
Title : register_sub
Usage :
Function: Register an anonymous code block for being executed in
one of the listener methods.
This method is probably mostly useful for testing purposes,
but who knows.
You may call this as a class method or an object method.
Example :
Returns : an instance of this class with the supplied anonymous
function overriding the specified listener method
Args : the code reference to register
the name(s) of the interface method(s) to register it for
(optional, if not specified the code block will be
registered for all 4 methods)TransactionListener interface methods
The following methods define the interface for TransactionListeners.
before_commit
Title : before_commit
Usage :
Function: Called before a commit is issued.
Any listener may veto a pending commit by returning
false. The default implementation returns true.
Example :
Returns : TRUE if the transaction is good to be committed, and
FALSE if it is vetoed.
Args : noneafter_commit
Title : after_commit
Usage :
Function: Called after a commit was issued.
The default implementation here does nothing.
Example :
Returns : ignored
Args : nonebefore_rollback
Title : before_rollback
Usage :
Function: Called before a rollback is issued.
A listener cannot veto a pending rollback. The return value
and even thrown exceptions will be ignored by Transaction.
Example :
Returns : ignored
Args : noneafter_rollback
Title : after_rollback
Usage :
Function: Called after a rollback is issued.
Example :
Returns : ignored
Args : none