Process Modeling Umberto Nanni Enterprise Information Systems 1 - PowerPoint PPT Presentation

D IPARTIMENTO DI I NGEGNERIA INFORMATICA AUTOMATICA E GESTIONALE A NTONIO R UBERTI Master Degree Programme in Manage gement ment Engin inee eeri ring En Enterprise erprise In Information formation Sys ystems ems Umbe mberto to Nan anni ni Process Modeling Umberto Nanni Enterprise Information Systems 1

Processes to be modeled service physical primary activities manipulation of physical objects support information the primary activities are the customers information management management and control business regulate relations between business process in the directional and operational value chain component Umberto Nanni Enterprise Information Systems 2

Some models for processes • Hierarchic • State Diagram (finite state machine) • DFD - Data Flow Diagram • WIDE - Workflow on an Intelligent and Distributed database Environment • Action Workflow • Petri Nets Umberto Nanni Enterprise Information Systems 3

model: Hierarchical Model Macroprocess SALES Warehouse Sales Product Process management management development Order Sales Forces Phase Planning processing management Order Material Invoice Activity Shipment reception preparation preparation Document Operation Pricing Packaging Load preparation Umberto Nanni Enterprise Information Systems 4

model: DFD – Data Flow Diagram process Data collection interface Data flow (external agent) label label label label label label Umberto Nanni Enterprise Information Systems 5

Data Flow A data flow (a directed link) represents any kind of flow (e.g., material or information): • a first endpoint must be a process • a second endpoint can be a process, or an interface, or a data collection • a data flow can be elementary or structured • a data flow can be an element of a collection Umberto Nanni Enterprise Information Systems 6

Sample DFD – Plan of Study (PoS) student check exam PoS PoS compo- sition PoS outcome PoS Plan of Study Umberto Nanni Enterprise Information Systems 7

Considerations on DFD • accompany the DFD – a DATA DICTIONARY – the textual description of each process • the first DFD (single process, with interfaces and interchange flows) is called “CONTEXT DIAGRAM” • hierarchical decomposition of processes (consistent with numbering) • limitations of DFD ... Umberto Nanni Enterprise Information Systems 8

DOT, USA, 1998 Umberto Nanni Enterprise Information Systems 9

DOT, USA, 1998 Umberto Nanni Enterprise Information Systems 10

model: WIDE – Workflow on an Intelligent and Distributed database Environment • PROCESS model – description of the activities and control structure – similar to Activity Diagram (UML) • INFORMATION model – data and documents necessary for the execution • ORGANIZATION model – structure and agents Umberto Nanni Enterprise Information Systems 11

Elements of the WIDE model task supertask business process <name> fork/join cycle conditional fork control flow begin/end Umberto Nanni Enterprise Information Systems 12

Travel Agency [BS01, SI per PA: Metodologie e Tecnologie, CNIPA] Travel selection !Approved Approved Travel cancellation Travel confirmation Preparation of documents Request of payment Shipment of documents Umberto Nanni Enterprise Information Systems 13

model: Action Workflow • activity – working task • action – requesting or making commitments • commitment – interaction CUSTOMER - SUPPLIER • process – structured set of activities Umberto Nanni Enterprise Information Systems 14

Action Workflow – Process modeling 1. Request (Preparation) 2. Acceptance (Negotiation) 3. Production (Execution) 4. Supply (Satisfaction) 1 2 TRANSACTION CUSTOMER PROVIDER 4 3 Umberto Nanni Enterprise Information Systems 15

Schemas and sample modeling Source: http://www.cnipa.gov.it/site/it-IT/ /La_Documentazione/In_archivio/Quaderni_AIPA/ Quaderno 1 (Introduction): “Reingegnerizzazione dei Processi e Workflow Management ” http://www.cnipa.gov.it/site/_contentfiles/00464500/464560_bpr.pdf Umberto Nanni Enterprise Information Systems 16

Basic Structure (secondary workflow) (secondary workflow) TRANSACTION customer provider (primary workflow) (secondary workflow) (secondary workflow) Umberto Nanni Enterprise Information Systems 17

Contextualization to public administration Public Citizen Administration Umberto Nanni Enterprise Information Systems 18

Process: land registry office Umberto Nanni Enterprise Information Systems 19

model: Petri Nets Structure G=(P  T,A), A  (P×T)  (T×P) Petri net: bipartite graph place transition Umberto Nanni Enterprise Information Systems 20

Petri nets: a model for processes [Carl Adam Petri, 1962] A Petri net is a 4-tuple P =(P,T,A,M 0 ) where: ) 3 P set of places T set of transitions set of arcs A  (P  T)  (T  P) A M 0 is the initial marking M: P  N Umberto Nanni Enterprise Information Systems 21

Some notation and terminology • each transition t  T has an input set °t  P and an output set t°  P (also called input/output places for t) • the same notation applies to places, set of places, set of transitions; e.g.: °p 3 ={t 1 } p° 3 ={t 2 } {t 1 , t 2 }°={p 1 , p 3 , p 4 , p 5 } • when a transition t has at least one token in each input place, it is enabled (or firable):  p  °t, M(p)  1 Input set for t 1 : °t 1 ={p 1 , p 2 } In the current p 1 p 2 marking: p 5 t 1 is enabled, while t 1 t 3 t 2 and t 3 are not. We write: t 2 p 4 t 1 p 3 M 0  Output set for t 1 : t 1 °={p 3 , p 4 } Umberto Nanni Enterprise Information Systems 22

Evolution of a Petri net An enabled transition can fire, deleting a token in each input place and creating a token in each output place p 1 p 2 p 5 M 0 =(2,1,0,0,0) t 1 M 0  M 1 t 3 t 1 t 2 M 1 =(1,0,1,1,0) p 3 p 4 A firable sequence is a sequence of transitions s =  t 1 ,t 2 ,...,t n  , t 1 t 2 t n s where M 0  M 1  M 2 ...  M n i.e., M 0  M n Umberto Nanni Enterprise Information Systems 23

Potential evolution of a Petri net Given a net P =(P,T,A,M 0 ): • a potentially firable transition t T is such that there exists a t t prefix sequence tT * , where t t is firable: M 0  • a potentially firable sequence of transitions sT * is such that ts there exists a prefix sequence tT * , where ts is firable: M 0  • a reachable marking M is such that there exists a firable s sequence s such that M 0  M • R(M 0 ) is the set of reachable markings • P R is the set of reachable places: P R = {p  P |  M  R(M 0 ), M(p)>0} Umberto Nanni Enterprise Information Systems 24

A special case: Finite State Machine A (Finite) State Machine is a Petri net where, for each transition t, both the input and the output places have cardinality one:  t  T, |°t|=|t°|=1 Example: Umberto Nanni Enterprise Information Systems 25

Workflow nets [Wil van der Aalst 1997] A workflow net is a Petri net where: 1. there exist two special places a source i with |°i|=0 a sink o with |o°|=0 2. for each node x  P  T, x is reachable from the source, and the sink is reachable from x b 1 5 c o i 3 6 d a 2 4 7 Umberto Nanni Enterprise Information Systems 26

Importance of WF-nets • robust, since they are based on a well formalized and studied model – Petri nets • strong properties which reduce the cost of evaluating properties which would be impractical to test on general Petri nets • some constructs have been added in order to comply more practical needs in modeling business processes (sometimes reintroducing complexity and unclear semantics) • established formalism to represent Business Processes, with high impact in industry, with translation tool from/to main industrial models (e.g., BPEL) • a pragmatic consideration: van der Aalst has collected more than 51000 citations – 34000 in the last 5 years Umberto Nanni Enterprise Information Systems 27