Designing Business Process Management Solutions using …takoehle/teaching/UniZH... · · 2009-09-01Designing Business Process Management Solutions using Open Standards and Patterns

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Business Integration Technologies

© 2009 IBM Corporation

Designing Business Process Management Solutions using Open Standards and Patterns

Part 2: Business Process Modeling Notation BPMN

Dr. Jana KoehlerIBM Zurich Research Laboratory


© 2009 IBM Corporation2 Business Process Management

Learning Objectives

� Understand and apply key concepts of the Business Process Modeling Notation (BPMN) – V 2.0

– process vs. choreography modeling

– activities, events, gateways

– execution semantics

– soundness = absence of lack of synchronization errors and deadlocks

� Exercise: BPMN model of the T Order management process

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Business Process Modeling Notation (BPMN)

� First initiative to develop a notation: September 2000

� Version 1.0 of the BPMN Standard (OMG): May 2004

– set of graphical symbols, informal semantics, many examples, first vendor support

� Version 1.1 with minor bug fixing: August 2007, about 60 vendors

� Version 2.0 accepted (Accenture, IBM/SAP/Oracle et al) in June 2009

– metamodel (unique exchange format), formally described semantics

events

gatewaysactivities

sequence flows

a first impression

�BPM for business and IT users

� graphical flow at business level

� textual refinements towards IT and runtime



Activity-Oriented Modeling of Behaviors

� Most commonly used and best understood approach

� Well established in various disciplines

– software modeling: UML activity diagrams

– “business informatics”: Event-driven Process Chains (EPC)

– IT systems: workflows

� Major concepts shared by all approaches

– activity (task, function, action) and its refinement into a subprocess

– explicitly prescribed order of activities in a flow diagram

– special types of diagram nodes to capture flow branching behavior (gateways, rules, connectors, control nodes)

• parallel + alternative branching, cycles

� We cover only a subset of the available modeling el ements

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EPC vs. BPMN vs. UML AD Notation

EPC

UML

BPMN

AcceptOrder

Validate Order

AnalyzeOrder

PerformCredit Check

RejectOrder

Reject

Accept

BPMN subsumes ARIS EPC



BPMN Standard

� BPM for business users as well as IT users

– acceptable and usable by the business community for general process modeling

– able to generate executable processes through a combination of graphical elements and supporting information (attributes)

� 2.0 standardization:

– metamodel for syntactic interoperability

– execution semantics to support semantic interoperability

– better support for data modeling and choreographies (protocol specification)

– BPMN to BPEL mapping to leverage existing BPEL technology

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BPMN Scope

� A modeling language -not a methodology!

� BPMN is intended to be methodology agnostic– methodologies will give

guidance as to the purpose and level of detail for modeling

– “BPMN is as complex as it needs to be. Just use what you need…”(Steven White)



Main Diagram Elements

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Main Diagram Elements: Activities

� Distinguished step in the process that

– takes a set of inputs and converts them into a set of outputs (either or both sets may be empty)

– encapsulates a specific business function

� Task (atomic process step, not further refined in the current model)

� Subprocess (refined with a another BPMN diagram)



Task Marker and Types of Tasks

manual (outside BPMS)

business rules task

script task (code for BPMS)

loop task

multi-instance task

compensation task

send task

receive task

service task

user task

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Main Diagram Elements: Connectors

� Sequence Flow

� Message Flow

� Association



Main Diagram Elements: Artifacts

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Group Across Pools



Data Flow

� Sequence and data flow are either decoupled or bound together

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Ad-Hoc Process for writing a book chapter



Data and Sequence Dependencies in the Write Book Ch apter Process

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Main Diagram Elements: Events

� Example of a rather vague definition (from the BPMN 2.0 Spec, p. 239):

– … something that “happens” during the course of a business process

– affects the process flow and usually has a cause or impact and in general requires or allows for a reaction

� A more specific definition (from the ARIS Method 7.0, 4-98, 10/2006)

– “By an event we understand the fact that an informa tion object has taken on a business-relevant state which is con trolling or influencing the further procedure of the business p rocess.”



Events in EPC and BPMN

event = object + state

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Event Types



Intermediate Events within normal Sequence Flow

� Represent things that happen during the normal operations of theprocess

– creation of the event (e.g. the sending of a message)

– response to the event (e.g. the receipt of a message)

message throwing message catching

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Intermediate Events attached to an Activity Boundar y

� Indicate that the activity should be interrupted when the event is triggered

– can be attached to either Tasks or Sub-Processes

� Used for error handling, exception handling, and compensation

intermediate timer, boundary, interrupting



Boundary Events

compensation events connecting to compensation tasks

non-interrupting message

interrupting error

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Link Events used as Off page Connector



Pools and Lanes� Pools represent participants in an interactive (B2B) Business Process Diagram

– only message flow between pools

� Lanes represent sub-partitions for the objects within a pool

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Main Diagram Elements: Gateways

� Exclusive (XOR) – Decision/Merge

� Event-based

� Inclusive (OR/IOR) – OR-Split/OR-Join

� Parallel (AND) – Fork/Join

� Complex



Process initiated by Event-based Gateway

message

conditional

signal

intermediate events

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Inclusive Gateway (OR)

Parallel Gateway (AND)

Exclusive Gateway (XOR)

Main Diagram Elements: Gateways

Semantics described in terms of token flow (from Petri Net Theory)

� State of the business process = distribution of tokens (marking) in the diagram

� Petri Net Theory offers a calculus of equations over token distributions

complex gateway: split behavior of OR + activation condition



OR-Join Semantics (page 438)

� Long-standing open research problem

– Find a semantics that fits intuition but can be formalized

– Find right trade-off between expressivity and tractability

– Define in such a way that it complies with current execution in BPEL

� “The Inclusive Gateway is activated if t least one incoming sequence flow has at least one Token and for each empty incoming sequenceflow, there is no Token in the graph anywhere upstream of this sequence flow.”

� Upstream: there is no directed path (formed by Sequence Flow) from a Token to this sequence flow unless the path visits the inclusive gateway or the path visits a node that has a directed path to a non-empty incoming sequence flow of the inclusive gateway.

� Upon execution, a Token is consumed from each incoming sequence flow that has a Token. A Token will be produced on some of the outgoing sequence flows. In order to determine the outgoing sequence flows that receive a Token, all conditions are evaluated. The evaluation does not have to respect a certain order. For every condition, which evaluates to true, a Token must be passed on the respective sequence flow. If and only if none of the conditions evaluates to true, the Token is passedon the default sequence flow. In case all conditions evaluate to false and a default flow has not been specified, the inclusive gateway throws an exception.

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OR-Join Example

For which tokens must these OR-Joins wait?

T1

T2



Example“Orchestration”

no pools and no message flows

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Collaboration Models - Public and Private Processes



Choreography Model

� A self-contained Choreography (no Pools or Orchestration) is a definition of the expected behavior, basically a procedural contract, between interacting Participants. While a normal Process exists within a Pool, a Choreography exists between Pools (or Participants). (p. 44)

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Choreography combined with Private Processes



Choreography within Collaboration

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Choreography Partners in Orchestration Model



Conversation DiagramA Conversation is the logical relation of Message exchanges.

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Exercise: The “T” Order Management Process

Task 2

Task

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� Task 1: Complete the initial diagram of the T Order Management process

� Task 2: Model the Create New Service process



Task 1: “T” Order Management Process

� Following the Reuse Transmission? decision:

– yes: reserve the transmission

– no: search for alternatives

• yes: determine the cost, confirm with the customer, does the customer accept?– yes: continue after the transmission reservation activity– no: close the request

• no: decline the request from the customer, close the request

� After a transmission has been reserved, switch on the service and schedule a visit at the site.

� Finally, update the customer service record and adjust the billing system.

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Task 2: Model the “Create New Service” Subprocess

� If a customer requests a new PSTN service, we first need to validate if the service is really offered at the requested time. A service offer may be restricted to a specific advertising period or it may not be available when the customer wants to have it provided. If the service request is valid, we continue to perform three checks, otherwise we close the request.

� The three checks that are independent of each other, but must all three be performed

– Eligibility of the customer for the service, e.g., is the customer eligible for an age-specific service or a service that can only be used in a bundle with other services?

– Credit history of the customer: is he paying well, what customer status does he have and does this imply constraints on the requested service?

– Technical prerequisites: is the service available at the requested location?

� The result of these checks is that the service is either possible or not. In the “no”case, we want to review other possibilities with the customer and iterate the subprocess again, i.e., begin with validating another service alternative, check the 3 criteria, etc.

IBM Zurich Research Laboratory - Business Integration Technologies


Background Reading

� All on BPMN http://www.bpmn.org/

� S. White, D. Miers, L. Fischer: BPMN Modeling and Reference Guide, Future Strategies, 2008

� The ORYX Editor at Hasso Plattner Institute

– http://bpt.hpi.uni-potsdam.de/Oryx

� B. Silver: BPMN Method and Style, Cody Cassedy Press, 2009

� OMG BPMN 2.0 Specification

– OMG Document bmi/2009-05-03

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IBM Zurich Research Laboratory - Business Integration Technologies


Summary Part 2

� BPMN is a key standard for BPM – 2.0 version provides

– expressive process modeling capabilities

– support for orchestration, conversation and choreography modeling to integrate business processes

– precisely defined execution semantics for better simulation and implementation

• textual refinements of the graphical model for direct IT executability

– unique metamodel for model exchange across tools

Documents

Designing Business Process Management Solutions using …takoehle/teaching/UniZH... · · 2009-09-01Designing Business Process Management Solutions using Open Standards and Patterns