eZ Components - WorkflowDatabaseTiein
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. contents:: Table of Contents


Introduction
============

The WorkflowDatabaseTiein component allows you to store workflows in a
relational database. It also provides a workflow execution environment that
makes workflow execution states persistent.
The persistence allows you to resume workflows between different PHP requests.


Class overview
==============

ezcWorkflowDatabaseExecution

  Workflow executer that suspends and resumes workflow execution states 
  to and from a database.

ezcWorkflowDatabaseDefinitionStorage
  Workflow definition storage handler that saves and loads workflow
  definitions to and from a database.


Database tables
===============

This component requires a specific set of tables to exist in your
database. As a reference of the tables and fields required we have provided a
schema for MySQL. To ease the installation process we also provide the database
independent .dba file.

Mysql schema
------------

This is the reference schema for MySQL 5.

.. include:: ../design/schema_mysql.sql
   :literal:


Database independent schema
---------------------------

To load the .dba definition into your database you must have the DatabaseSchema
component installed. Save the file to your harddrive and use the following code
to load it:

.. include:: load_dba.php
   :literal:

You may need to extend 'workflow.dba' to contain the proper path to the file.


Usage
=====

Storing a workflow to database
------------------------------

This example shows how to store a workflow to database. The example assumes
that the workflow is available in the $workflow variable.

.. include:: example_save_to_database.php
   :literal:

Loading a workflow from the database
------------------------------------

This example loads the workflow named 'test' into the variable $workflow.

.. include:: example_load_from_database.php
   :literal:

Executing a workflow
--------------------

Executing a workflow is done by calling the method start on the execution
object. This example shows how to execute the workflow test that is stored in
the database. The id that is returned by the execute method identifies this
execution thread and can be used later if the workflow must be resumed.

Executing a workflow using the ezcWorkflowDatabaseExecution executer requires
the definition of the workflow (and all of its sub-workflows) to be stored in
the database.

.. include:: example_execute.php
   :literal:


Resuming a workflow execution
-----------------------------

If a workflow execution is suspended and needs to be resumed the method resume
should be used. This example shows how to resume a suspended workflow and
provide the input data 'choice'. The id is the one provided by the original call
to execute.

.. include:: example_resume.php
   :literal:

Cancelling a workflow execution
-------------------------------

If a workflow execution is suspended it can be cancelled by calling the cancel()
method on the executer object.

.. include:: example_cancel.php
   :literal:

This method is also automatically called when the workflow execution reaches a
ezcWorkflowNodeCancel node.

When the execution of a workflow is cancelled all nodes that are currently
activated will be deactivated and the optional sequence of final activities
that starts in $workflow->finallyNode is activated.

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