Welcome! A Workflow Engine for PHP 5 or: Graph-Oriented Programming with PHP Sebastian Bergmann http://sebastian-bergmann.de/ March 14 th 2008

A Workflow Engine for PHP 5

or: Graph-Oriented Programming with PHP

Sebastian Bergmann

http://sebastian-bergmann.de/

March 14 th 2008

Who I Am Sebastian Bergmann Contributor to the PHP Project since 2000 Creator of PHPUnit Developer for eZ Systems AS Author, Consultant, Trainer

Sebastian Bergmann

Contributor to the PHP Project since 2000

Creator of PHPUnit

Developer for eZ Systems AS

Author, Consultant, Trainer

Who Are You? Your Background PHP 5? OOP? eZ Components? Workflow?

Your Background

PHP 5?

OOP?

eZ Components?

Workflow?

Introduction Business enterprises need to reduce the cost of doing business and continually develop new services and products. Enterprise Content Management helps with storing business-critical content (customer data, documents, etc.) in a central repository and in a unified way. Workflow Management provides the methodologies and software that help with organizing the processes that operate on this content inside an organization.

Business enterprises need to reduce the cost of doing business and continually develop new services and products.

Enterprise Content Management

helps with storing business-critical content (customer data, documents, etc.) in a central repository and in a unified way.

Workflow Management

provides the methodologies and software that help with organizing the processes that operate on this content inside an organization.

What is Workflow Management? “The automation of a business process, in whole or parts, where documents, information or tasks are passed from one participant to another to be processed, according to a set of procedural rules” [RA01]

“The automation of a business process, in whole or parts, where documents, information or tasks are passed from one participant to another to be processed, according to a set of procedural rules” [RA01]

What is Workflow Management? “Technology supporting the reengineering of business and information processes. It involves: (1) defining workflows, i.e., describing those aspects of a process that are relevant to controlling and coordinating the execution of its tasks [...], and (2) providing for fast (re)design and (re)implementation of the processes as business needs and information systems change” [DG95]

“Technology supporting the reengineering of business and information processes. It involves: (1) defining workflows, i.e., describing those aspects of a process that are relevant to controlling and coordinating the execution of its tasks [...], and (2) providing for fast (re)design and (re)implementation of the processes as business needs and information systems change” [DG95]

Motivation The workflow of eZ Publish 3

Activity-Based Workflow Mgmt. Who must do what when and how ?

Activity-Based Workflow Mgmt. Who must do what when and how ? Directed Graph Nodes represent activity steps Edges between nodes represent the flow Control Flow Data Flow Nodes can have service objects attached to them

Directed Graph

Nodes represent activity steps

Edges between nodes represent the flow

Control Flow

Data Flow

Nodes can have service objects attached to them

Workflow Patterns W.M.P. van der Aalst, A.H.M. ter Hofstede, B. Kiepuszewski, and A.P. Barros. Workflow Patterns . Requirements for Workflow Languages Vocabulary to compare Workflow Languages

W.M.P. van der Aalst, A.H.M. ter Hofstede, B. Kiepuszewski, and A.P. Barros. Workflow Patterns .

Requirements for Workflow Languages

Vocabulary to compare Workflow Languages

Workflow Patterns Basic Control Flow Patterns Sequence, Parallel Split (AND-Split), Synchronization (AND-Join), Exclusive Choice (XOR-Split), Simple Merge (XOR-Join) Advanced Branching and Synchronization Multi-Choice (OR-Split), Synchronizing Merge (OR-Join), Multi-Merge, Discriminator Structure Arbitrary Cycles, Cancel Case, Implicit Termination

Basic Control Flow Patterns

Sequence, Parallel Split (AND-Split), Synchronization (AND-Join), Exclusive Choice (XOR-Split), Simple Merge (XOR-Join)

Advanced Branching and Synchronization

Multi-Choice (OR-Split), Synchronizing Merge (OR-Join), Multi-Merge, Discriminator

Structure

Arbitrary Cycles, Cancel Case, Implicit Termination

Graph-Oriented Programming Implementation technique for graph-based execution languages Strategy for implementing graph execution on top of an object-oriented programming language Original implementation: JBoss jBPM

Implementation technique for graph-based execution languages

Strategy for implementing graph execution on top of an object-oriented programming language

Original implementation: JBoss jBPM

Graph-Oriented Programming Provides the means to structure software around graphs Adds wait states to object-oriented programming language Ability to suspend and resume executions

Provides the means to structure software around graphs

Adds wait states to object-oriented programming language

Ability to suspend and resume executions

Graph-Oriented Programming

Graph-Oriented Programming

Graph-Oriented Programming

Workflow Virtual Machine Sérgio Miguel Fernandes, João Cachopo, and António Rito Silva. Supporting Evolution in Workflow Design Languages . Isolate the core of the Workflow Management System from the Workflow Description Language No standard Workflow Description Language Workflow Description Languages change „Compile“ frontend Workflow Description Language(s) to backend representation

Sérgio Miguel Fernandes, João Cachopo, and António Rito Silva. Supporting Evolution in Workflow Design Languages .

Isolate the core of the Workflow Management System from the Workflow Description Language

No standard Workflow Description Language

Workflow Description Languages change

„Compile“ frontend Workflow Description Language(s) to backend representation

Micro-Workflow Architecture Dragos A. Manolescu. An Extensible Workflow Architecture with Objects and Patterns . Object-Oriented Original implementation in Smalltalk Component-Oriented Separation of concerns Components are exchangeable

Dragos A. Manolescu. An Extensible Workflow Architecture with Objects and Patterns .

Object-Oriented

Original implementation in Smalltalk

Component-Oriented

Separation of concerns

Components are exchangeable

Micro-Workflow Architecture Components Core Execution Process Synchronization Persistence Worklist Manual Intervention History Monitoring Federated Workflow

Components

Core

Execution

Process

Synchronization

Persistence

Worklist

Manual Intervention

History

Monitoring

Federated Workflow

ezcWorkflow Reusable workflow engine component Part of the eZ Components Version 1.0 released on July 2 nd 2007 Version 1.1 released on December 17 th 2007 New node type to conveniently express loops Version 1.2 exptected to be released in June Support for the Cancel Case workflow Plugin system to customize / extend the engine Visualization of workflow execution Developed as part of my Diploma Thesis

Reusable workflow engine component

Part of the eZ Components

Version 1.0 released on July 2 nd 2007

Version 1.1 released on December 17 th 2007

New node type to conveniently express loops

Version 1.2 exptected to be released in June

Support for the Cancel Case workflow

Plugin system to customize / extend the engine

Visualization of workflow execution

Developed as part of my Diploma Thesis

Interlude: eZ Components Provide a solid platform for PHP application development Clean and simple API Excellent documentation Keep backward compatibility for longer periods of time Stable and few regressions Clean IP, Open Source friendly

Provide a solid platform for PHP application development

Clean and simple API

Excellent documentation

Keep backward compatibility for longer periods of time

Stable and few regressions

Clean IP, Open Source friendly

Interlude: eZ Components <?php require 'ezc/Base/base.php' ; function __autoload ( $className ) { ezcBase :: autoload ( $className ); } pear channel-discover components.ez.no pear install ezc/ezcomponents

pear channel-discover components.ez.no

pear install ezc/ezcomponents

ezcWorkflow Pragmatic approach to describe workflows through objects that encapsulate the workflow patterns A workflow definition is an object graph than can be programmatically created using the Workflow Definition API or loaded from an XML file and executed via the Workflow Execution API

Pragmatic approach to describe workflows through objects that encapsulate the workflow patterns

A workflow definition is an object graph than can be

programmatically created using the Workflow Definition API or

loaded from an XML file

and executed via the Workflow Execution API

ezcWorkflow Data Storage Workflow Core Wf Definition API Wf Execution API GUI XML Mail / SOAP / ...

ezcWorkflow Workflow Definition API Exposes functionality to create , modify , and delete workflow definitions Workflow Execution API Exposes functionality to start , suspend , resume , and stop workflow execution Exposes functionality to monitor workflow execution

Workflow Definition API

Exposes functionality to create , modify , and delete workflow definitions

Workflow Execution API

Exposes functionality to start , suspend , resume , and stop workflow execution

Exposes functionality to monitor workflow execution

ezcWorkflow $workflow = new ezcWorkflow ( 'Test' ); $input = new ezcWorkflowNodeInput ( array( 'choice' => new ezcWorkflowConditionIsBool ) ); $workflow -> startNode -> addOutNode ( $input ); Example: Defining a workflow

ezcWorkflow $branch = new ezcWorkflowNodeExclusiveChoice ; $branch -> addInNode ( $input ); $branch -> addConditionalOutNode ( new ezcWorkflowConditionVariable ( 'choice' , new ezcWorkflowConditionIsTrue ), new ezcWorkflowNodeAction ( 'PrintTrue' ) ); // ... Example: Defining a workflow

ezcWorkflow $merge = new ezcWorkflowNodeSimpleMerge ; $merge -> addInNode ( $true ) -> addInNode ( $false ) -> addOutNode ( $workflow -> endNode ); Example: Defining a workflow

ezcWorkflow $merge = new ezcWorkflowNodeSimpleMerge ; $merge -> addInNode ( $true ) -> addInNode ( $false ) -> addOutNode ( $workflow -> endNode ); $storage = new ezcWorkflowDefinitionStorageXml ( '/path/to/xml/files' ); $storage -> save ( $workflow ); Example: Saving a workflow to XML

ezcWorkflow <?xml version = &quot;1.0&quot; encoding = &quot;UTF-8&quot; ?> <workflow name = &quot;Test&quot; version = &quot;1&quot; > <node id = &quot;1&quot; type = &quot;Start&quot; > <outNode id = &quot;2&quot; /> </node> <node id = &quot;2&quot; type = &quot;Input&quot; > <variable name = &quot;choice&quot; > <condition type = &quot;IsBool&quot; /> </variable> <outNode id = &quot;3&quot; /> </node> <node id = &quot;3&quot; type = &quot;ExclusiveChoice&quot; > <condition type = &quot;Variable&quot; name = &quot;choice&quot; > <condition type = &quot;IsTrue&quot; /> <outNode id = &quot;4&quot; /> </condition> <condition type = &quot;Variable&quot; name = &quot;choice&quot; > <condition type = &quot;IsFalse&quot; /> <outNode id = &quot;5&quot; /> </condition> </node> <node id = &quot;4&quot; type = &quot;Action&quot; serviceObjectClass = &quot;PrintTrue&quot; > <outNode id = &quot;6&quot; /> </node> <node id = &quot;5&quot; type = &quot;Action&quot; serviceObjectClass = &quot;PrintFalse&quot; > <outNode id = &quot;6&quot; /> </node> <node id = &quot;6&quot; type = &quot;SimpleMerge&quot; > <outNode id = &quot;7&quot; /> </node> <node id = &quot;7&quot; type = &quot;End&quot; /> </workflow> Example: Saving a workflow to XML

ezcWorkflow $merge = new ezcWorkflowNodeSimpleMerge ; $merge -> addInNode ( $true ) -> addInNode ( $false ) -> addOutNode ( $workflow -> endNode ); $storage = new ezcWorkflowDatabaseDefinitionStorage ( ezcDbFactory :: create ( $dsn ) ); $storage -> save ( $workflow ); Example: Saving a workflow to a database

ezcWorkflow $execution = new ezcWorkflowDatabaseExecution ( $db ); $execution -> setWorkflow ( $workflow ); $executionId = $execution -> start (); // ... $execution -> resume ( $executionId , array( 'choice' => true ) ); Example: Executing a workflow

ezcWorkflow $execution = new ezcWorkflowTestExecution ; $execution -> setWorkflow ( $workflow ); $execution -> setInputVariable ( 'choice' , true ); $execution -> start (); Example: Testing a workflow

ezcWorkflow OXID eSales GmbH has adopted ezcWorkflow Thomas Nunninger (of OXID eSales GmbH) has developed a persistence backend for Zend_Db Dave Heath has developed a persistence backend for Doctrine Early Adopters

OXID eSales GmbH has adopted ezcWorkflow

Thomas Nunninger (of OXID eSales GmbH) has developed a persistence backend for Zend_Db

Dave Heath has developed a persistence backend for Doctrine

The End Thank you for your interest! These slides will be available shortly on http://sebastian-bergmann.de/talks/.

Thank you for your interest!

These slides will be available shortly on http://sebastian-bergmann.de/talks/.

Bibliography Sebastian Bergmann. Design and Implementation of a Workflow Engine. Diploma Thesis to obtain the degree of Diplom-Informatiker (Univ.) from the Institute of Computer Science of the University of Bonn, Germany, February 2007.

Sebastian Bergmann. Design and Implementation of a Workflow Engine. Diploma Thesis to obtain the degree of Diplom-Informatiker (Univ.) from the Institute of Computer Science of the University of Bonn, Germany, February 2007.

Bibliography Rob Allen. Workflow: An Introduction . In: Workflow Handbook, Workflow Management Coalition, 2001. Dimitrios Georgakopoulos and Mark F. Hornick and Amit P. Sheth. An Overview of Workflow Management: From Process Modeling to Workflow Automation Infrastructure . In: Distributed and Parallel Databases, Volume 3, Number 2, Pages 119-153, 1995.

Rob Allen. Workflow: An Introduction . In: Workflow Handbook, Workflow Management Coalition, 2001.

Dimitrios Georgakopoulos and Mark F. Hornick and Amit P. Sheth. An Overview of Workflow Management: From Process Modeling to Workflow Automation Infrastructure . In: Distributed and Parallel Databases, Volume 3, Number 2, Pages 119-153, 1995.

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This presentation material is published under the Attribution-Share Alike 3.0 Unported license.

You are free:

to Share – to copy, distribute and transmit the work.

to Remix – to adapt the work.

Under the following conditions:

Attribution. You must attribute the work in the manner specified by the author or licensor (but not in any way that suggests that they endorse you or your use of the work).

Share Alike. If you alter, transform, or build upon this work, you may distribute the resulting work only under the same, similar or a compatible license.

For any reuse or distribution, you must make clear to others the license terms of this work.

Any of the above conditions can be waived if you get permission from the copyright holder.

Nothing in this license impairs or restricts the author's moral rights.