Petri net based modelling of workflow system an overview
This presentation is the property of its rightful owner.
Sponsored Links
1 / 39

Petri net-based modelling of workflow system : An overview PowerPoint PPT Presentation


  • 146 Views
  • Uploaded on
  • Presentation posted in: General

Petri net-based modelling of workflow system : An overview. Professor : Dr. Ou-Yang Reporter :陳星豪 李高樺 洪淨池 魏廷璋. Outline. 1.Introduction 2. Workflow and workflow management system 3. Petri nets 4. Petri net-based workflow modeling 5. Petri net-based workflow software. Introduction.

Download Presentation

Petri net-based modelling of workflow system : An overview

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Petri net based modelling of workflow system an overview

Petri net-based modelling of workflow system:An overview

Professor:Dr. Ou-Yang

Reporter:陳星豪 李高樺

洪淨池 魏廷璋


Outline

Outline

1.Introduction

2. Workflow and workflow management system

3. Petri nets

4. Petri net-based workflow modeling

5. Petri net-based workflow software


Introduction

Introduction


Introduction1

Introduction

  • The core of workflow system is the notion of business process, which is a set of activities with a common goal

  • Workflow符合企業先前定義的需求,支援執行一連串需要使用人力以及各種資源的活動


Introduction2

Introduction

  • Petri nets are applied in different discrete-event dynamic systems, which are characterised by parallelism and synchronization

  • Petri nets-based modelling and analysis of workflow and workflow system is an active research area in academic

  • A small number of vendor have developed Petri nets-based workflow management system (WfMS)


Workflow and workflow management system

Workflow and workflow management system


Workflow and workflow management system1

Workflow and workflow management system

  • 1970年代,workflow的概念從工廠自動化的觀念中延伸而出,第一個workflow的雛形被發展出來

  • 1970~1980年間,Backtalk、Office Talk-P、Office Information System是最早發行的workflow系統雛形

  • 1980年代晚期開始,WfMS和ㄧ些computer-based system進行結合,例如:DBMS、document imaging或e-mail


Workflow

Workflow系統特徵

  • 一個workflow本身就是一個流程,使文件、資訊或工作在一個與多個參與者之間傳遞,共同協調執行,涵蓋到組織之間與內部的資訊流和控制流

  • Workflow Management Coalition

    • A Workflow as a computerised-based facilitation or automation of business process, in whole or part

  • A specific software system, WfMS, manages and executes workflow through the execution of software whose order of execution is driven by a computer representation of the workflow logic


Workflow1

Workflow系統特徵

  • WfMS由兩元件所組成

    • The workflow model(process definition)

    • The workflow execution module(workflow enactment service )


Workflow system component and phases

Workflow system component and phases


Workflow2

Workflow型態

  • 以流程定義與工作派工來看,有三種型態workflow

    • Production workflow

      • 固定的工作定義與執行次序

    • Administrative workflow

      • Cases 大致遵循原本已定義完成的程序,但是有另一條途徑供選擇

    • Ad hoc workflow

      • 以事先定義的流程樣版來驅動cases進行

      • 流程樣版能被修正以符合某些特定cases的需求


Petri nets

Petri nets


Petri nets1

Petri nets

  • 一種modelling工具,由Petri所建構

  • 圖形化概念具有自我文件化(self-documenting)的能力,成為從事設計流程的有力工具

  • 建立數學模式來描述系統的行為

  • 驗證模式

  • 適用於離散事件動態系統(discrete event dynamic systems)的modelling與分析,具有平行與同步作業的特性


Petri nets2

Petri nets

  • Three structural components

    • Places

    • Transitions

    • Arcs

  • Places以圓圈表示,代表系統的狀態與條件

  • Transitions以長柱形或長盒形表示,描述可能改變系統狀態的事件

  • Places與Transitions之間的關係以單一方向之Arcs連結

  • 兩個相同型態的節點之間不能相互連結

  • 系統的動態行為可以用tokens來呈現


Petri nets3

Petri nets

  • Petri nets的正式定義為

    • A Petri net is a 4-tuple N = {P, T, F, M0}

M which represents a state of the modelled system is a distribution of tokens over the set of places


Petri net model of workflow

Petri net model of workflow


Petri nets4

Petri nets

  • Two classes of properties of Petri net-based model system

    • Behavioural or marking dependent properties

      • Depending on the initial marking of the model

    • Structural properties

      • Relate to the structure of the modeled system and independent of the initial marking


Petri net based workflow modeling

Petri net-based workflow modeling


Workflow modelling

Workflow modelling

  • It is criticized that they have

    • no needed functionality

    • no clear set of definition

    • no general conceptual model


Petri net based workflow modeling1

Petri net-based workflow modeling

  • Zismann第一次應用Petri nets在辦公室流程上,為workflow系統的早期想法

  • Ellis延伸Zismann,推出Information Control Net (ICN),並且應用在辦公室資訊系統的建構

  • Vander Aalst已經證實workflow可以與Petri net完全結合

  • Vander Aalst提出workflow有三種不同的維度:process、case以及resource


Petri net based workflow modeling2

Petri net-based workflow modeling

  • 每一個workflow的工作由transition呈現

  • Places則是描繪出一個需執行任務之pre-condition與post-condition,或是所需的資源

  • 弧線表達出任務之間的邏輯關係以及它的流向

  • Example


Petri net model of workflow1

Petri net model of workflow


Resource modeling of workflow

Resource modeling of workflow

  • 前ㄧ模式只是描繪出一個workflow流程的單一instance,沒有討論到時間或資源的觀點

  • 實際的情況下,每一個流程可能需要執行超過一個以上的instance

  • Example


Resource modeling of workflow1

Resource modeling of workflow


Petri net based workflow software

Petri net-based workflow software


Petri net based workflow software1

Petri net-based workflow software

  • Protos

    • to export the processes modeled with Protos into some WfMS products such as COSA and FLOWer

  • Structware

    • a tool that allows the designer to design and simulate business processes based on Petri net models.


Petri net based workflow software2

Petri net-based workflow software

  • ExSpect

    • a business process modeling tool, able to model and analyze workflow processes in terms of Petri nets

  • Woflan

    • interfaces with the other commercial workflow products such as COSA , Staffware and Protos

  • INCOME


Modelling and qualitative analysis of workflow

Modelling and qualitative analysis of workflow

  • qualitative analysis

    • deadlock freeness

    • the correct flow of the work

    • absence of overflow

    • the presence of certain mutual exclusion wherever shared resource are used

  • mainly concentrated on structural modelling and analysis of the qualitative properties of workflow processes


Temporal constraint petri net tcpn

Temporal Constraint Petri Net(TCPN)

  • a modified version of an ordinary Petri net

  • has been used to model workflow application at conceptual level and as a test-bed to verify the system properties.

  • Each task is decomposed into some primitives and therefore the states between the primitives can be represented. Task dependencies are categorized into control-flow dependency, value dependency and external dependency


Business procedure net bp net

Business Procedure net (BP-net)

  • Free software

  • It is proposed for representation, validation and verification business processes.

  • Then this model has been modified into a workflow net (WF-net) as a sound model for workflow

  • In order to obtain a strong sound workflow model, he has added 1-safe property to WF-net


Workflow authorization model

Workflow Authorization Model

  • This model ensures that in a workflow system, authorized resources are granted privileges on required tasks only while the task is being executed


Inter organizational workflow

Inter-Organizational Workflow

  • Inter-organizational workflow and the availability of the Internet have affect workflow technology

  • SGML

    • A Petri net structure as a base layer

    • can be used in a distributed environment

  • CPN-based Colored Petri-Net


Workflow fragmentation

Workflow Fragmentation

  • Ad hoc changes

    • related to rare events

  • Radical changes

  • Evolutionary changes

    • are often the outcomes of reengineering the system


Object oriented modeling

Object Oriented Modeling

  • Modular Process Nets

  • Higher-Order Object Net (HOON)

  • Business Process Petri nets (BPP-nets)


Petri net based modelling of workflow system an overview

GSPN

  • The one that mostly has been used

  • Continuous Time Markov Chain

    • Time

    • Conversion


Gspn modeling

GSPN Modeling


Standard petri net

Standard Petri-net


Petri net based modelling of workflow system an overview

GSPN


Petri nets5

Petri nets

  • OCPN(Object Composition Petri nets)

  • XOCPN (eXtended Object Composition Petri Net)

  • DOCPN (Distributed Object Composition Petri Net)

  • TSPN (Time Stream Petri Net)


  • Login