Semantics (requirements) of Business Process

50 %
50 %
Information about Semantics (requirements) of Business Process

Published on December 8, 2008

Author: ang.chen



Discuss the semantics requirements of business process, mainly for the modeling of control-flow, dataflow, and transaction in business process modeling

Semantics (requirements) of Business Process Ang Chen 31 Jan. 2008

Objective: to observe • The requirements of BP semantics via Workflow Patterns and BPEL • The role of Petri Net in BP modeling: Graphical notation? Semantics foundation? Executable language? • Advantages / disadvantages of using PN as semantics basis of BP (e.g. comparing with Pi-calculus) • The missing part of BP modeling with PN, i.e. the data-flow A.Chen, 31 jan 2008 2

Papers • [1]. Workflow Patterns. W.M.P van der Aalst, A.H.M. ter Hofstede, B. Kiepuszewski, and A.P. Barros. Distributed and Parallel Databases, 14(3), July 2003 • [2]. Formal semantics and analysis of control flow in WS-BPEL. Science of Computer Programming,Volume 67, Issues 2-3, 1 July 2007. Chun Ouyang, Eric Verbeek, Wil M.P. van der Aalst, Stephan Breutel, Marlon Dumas and Arthur H.M. ter Hofstede • [3]. A pi-calculus based semantics for WS-BPEL. Journal of Logic and Algebraic Programming,Volume 70, Issue 1, January 2007. Roberto Lucchi and Manuel Mazzara • [4]. Information System Behavior Specification by High-Level Petri Nets. A. Oberweis, P. Sander. ACM Transactions on Information Systems,Vol. 1, No. 4, October 1996 • [5]. Petri Net + Nested Relational Calculus = Dataflow. Jan Hidders, Natalia Kwasnikowska, Jacek Sroka, Jerzy Tyszkiewicz, and Jan Van den Bussche. 2005 A.Chen, 31 jan 2008 3

Topics • Workflow Patterns [1] and BPEL: they represent requirements of business process modeling in academic and industry, respectively • Semantics (of BPEL control-flow): Petri Net [2], Pi-Calculus [3] • Data-Flow modeling: [4] [5] • Not included: Transaction A.Chen, 31 jan 2008 4

Topics [1] Workflow realize Petri Net patterns formalization [2] use [4] [5] BPEL Data-Flow Modeling formalization [3] Pi-Calculus A.Chen, 31 jan 2008 5

Outline • Non-local semantics of workflow patterns • BPEL formalization • Data-Flow Modeling in BP • Conclusion A.Chen, 31 jan 2008 6

Non-local semantics of Workflow Patterns

Workflow patterns • [1]. identifies 20 control-flow patterns and uses them to evaluate products • Basic constructs (1-5): sequence, join, split • Advanced branching and synchronization (6-9): merges • Structural (10-11): arbitrary cycle, implicit termination • Multi-instances (12-15) • State-Based (16-18) • Cancellation (19-20) A.Chen, 31 jan 2008 8

Non-local semantics (Join) I A D split B join C E • Non-blocking (asynchronous) Join (N of M): select N from M without waiting M inputs •xor-join:1 of M non-blocking join, D or E are activated once per case •multi-merge: D, E can be activated several times per case •discriminator: D, E can be activated several times, then reset A.Chen, 31 jan 2008 9

Non-local semantics (Join) II B E A split join G C F • In non-blocking join, the connector needs non-local information to take decision A.Chen, 31 jan 2008 10

Non-local semantics of workflow patterns • Most workflow patterns need non-local information between the activities, e.g. merge, case cancellation, cycles with multiple instances ... A.Chen, 31 jan 2008 11

Role of PN • PN can be a semantics basis • pros: easy to be verified for analysis purpose • cons: few patterns can be modeled directly due to its local semantics • Not easy to directly model BP with PN, extension of PN semantics is necessary A.Chen, 31 jan 2008 12

BPEL Formalization

BPEL • Business Process Execution Language based on Web Service, for the composition of Web Service • Units of composition: Activity, Scope • Control-Flow constructs: sequence, flow, switch, pick, while, link, fault, compensation • The specification does not provide a formal semantics, thus not clear (or ambiguous) in some details, e.g. completion conditions of parallel tasks A.Chen, 31 jan 2008 14

BPEL Semantics • Semantics of BPEL control-flow in Petri Net [2] and Pi-Calculus [3] • Both: obtain unambiguous semantics of BPEL • [2] provides static analysis methods, e.g. find unreachable activities • [3] possible to verify the behavioral equivalence of processes (future work) A.Chen, 31 jan 2008 15

Petri Net [2] to skip Y Ready to skip Y Ready Start Y Start skip Y X skip Run X X Run X C Y Y Completed X skipped Y Completed skipped Finished Activity X Y ! :-) Finished Scope Q • Activities and scopes are transformed into PN structure • State-oriented, easy to find case states A.Chen, 31 jan 2008 16

Pi-Calculus [3] • Formalization of control-flow is quite direct, but difficult to read • Abstraction of service is well preserved, e.g. action signature • Channels are used to handle faults and compensations • States of processes are encoded, however, states of cases are lost A.Chen, 31 jan 2008 17

BPEL formalization • There has been debates on the semantics basis of BP languages, e.g. PN vs. Pi-calculus • Each approach has its advantages • Till now, verifications are limited to static control-flow analysis • Data-flow analysis is missing A.Chen, 31 jan 2008 18

Data-Flow Modeling in BP

Data-Flow • Very general topic, many work have been done in database and parallel computing domain • Few publications in BP modeling, especially the integration of Control-Flow and Data-Flow (e.g. be able to extract CF from DF) • [4] , [5] try to address the data-flow problem in information system with Petri Net (control-flow + data-flow) A.Chen, 31 jan 2008 20

Data-Flow modeling [4] • [4] proposes Predicate/Transition Net + Nested Relation Calculus • Add formally defined behaviors to information systems • Processes are modeled by Predicate/Transition Net, tokens are relation instances • A different approach than CRUD in SQL to manage data (based on insertion and deletion of tuples) A.Chen, 31 jan 2008 21

NR/T Net • Places are relations, relation instances are sets of tuples • Use tuples and filter table to manipulate relation instances • Filter tables inscribed on PN arcs give rules of manipulating instances (Inclusion order vs. Object order) • Transitions are annotated by logical formulas A.Chen, 31 jan 2008 22

Data-Flow modeling [5] • [5] : Petri Net + Nested Relational Calculus = Data-Flow Language • Use operations on set and record • Edge annotation (simple condition), transition label (set operations, user-defined labels) • Use simple control-flow, it is designed to describe the flow of large amount of data • CRUD operations on data are not concerned A.Chen, 31 jan 2008 23

Data-Flow • Control-flow is a particular kind of data- flow • No convenient solutions (yet) for data-flow modeling in BP • Related topic: process mining tries to discover control-flow from observed data- flow A.Chen, 31 jan 2008 24

Conclusion • This study motivates to propose an approach which: • Integrates Control-Flow and Data-Flow • Supports relational data model • Based on PN or Process algebra, or both • Can be a semantics basis of BPEL and other languages • Supports all workflow patterns, if possible A.Chen, 31 jan 2008 25

BP Modeling with ID- Net • Places are typed, e.g. by relations. Tokens are identifications, e.g. relation keys • Transitions are processes whose behaviors are described by process algebra • Operations on relational data are attached to the transition process without changing the ID-Net’s control-flow, i.e. data-flow integration • Both case state and process state are traceable A.Chen, 31 jan 2008 26

Add a comment

Related presentations

Related pages

BRG: Semantics of Business Vocabulary and Business Rules ...

... the Business Semantics of ... the first Interim Specification document of the Semantics of Business Vocabulary and Business ... business process ...
Read more

Business semantics management - Wikipedia, the free ...

Business Semantics Management ... between stakeholders are reached that meets the semantic integration requirements. ... Business Process ...
Read more

BPMN 2: Business Semantics for Business Processes

Business Semantics for Business Processes ... Requirements. Generalization (Business) ... in BPMN 2 Model Library ...
Read more

The Application Of Semantics In Business Process ...

The Application Of Semantics In Business Process Information ... processes to be aligned with overall business needs, requirements and objectives of ...
Read more

Semantics of business process vocabulary and process rules

... Semantics of Business Process Vocabulary and ... Going from requirements analysis to design phase is considered as one of the most complex and ...
Read more

Semantics-based Business Process Model Similarity

Semantics-based Business Process Model ... Business process ... If the choice of words of the labels representing the business semantics is ...
Read more

On the Formal Semantics of the Extended Compliance Rule ...

On the Formal Semantics of the Extended ... formal semantics. Keywords: business process ... processes: Fundamen-tal requirements and their ...
Read more

A Formal Semantics for the Business Process Execution ...

A Formal Semantics for the Business Process Execution Language for Web Services Roozbeh Farahbod, ... ware requirements, including their elicitation, ...
Read more

Integrating the Semantics of Events, Processes and Tasks ...

Tasks across Requirements Engineering Layers ... Faculty of Economics and Business Administration, ... executable semantics by means of process algebra.
Read more