BPMN Series Timer Events – Best Practices and Common Mistakes

© Good e-Learning 2014. All rights reserved.

BPMN Series

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BPMN 2.0 Best Modeling Practices – Part 2

Good e-Learning’s complete guide to BPMN 2.0

by Gregor Polančič

BPMN Series Timer Events – Best Practices and Common Mistakes

© Good e-Learning 2014. All rights reserved.

Introduction

Business process model and notation (BPMN) definesa meta-model (i.e. abstract syntax) and a notation (i.e.visual process elements and rules about how to usethem) for creating business process diagrams andexecutable process models.

However the approach (i.e. “how to use BPMNelements in business process diagrams”) and style (i.e.“how to create unambiguous diagrams”) are out ofthe scope of BPMN specification.

This is the second part of the slides, which address the modeling ‘style’ by presenting four best practices that should be followed when creating BPMN diagrams.

These best practices can be obtained from the book ‘BPMN Modeling and Reference Guide. Future Strategies Inc., Lighthouse Pt, FL, 2008.’

BPMN Series Timer Events – Best Practices and Common Mistakes

© Good e-Learning 2014. All rights reserved.

BP#7: Use ‘OR’ gateways in pairs (1/2)

When using an inclusive gateway-based branch (i.e. OR split), the number of active outgoing paths can range from ‘zero’ to ‘all’

A way to avoid unexpected behavior when process paths converge is to use these type of gateways in pairs (divergence – convergence)

Cond 2

Cond 1

Cond 3

Number of active

outgoing flows?

Task

When process paths converge in anuncontrolled way, a task may be performed a

different number of times!

BPMN Series Timer Events – Best Practices and Common Mistakes

© Good e-Learning 2014. All rights reserved.

BP#7: Use gateways in pairs (2/2)

Cond 3

Cond 2

Cond 3

Task 1

Task 2

Task 3

Task 4

Task 5

Cond 3

Cond 2

Cond 3

Task 1

Task 2

Task 3

Task 4

Task 5

In this diagram Task 5 will be performed only once, because the conditional

flows converge in a controlled way

WARNING- unexpected behavior. In this diagram Task 5 will be performed

as many times as the true conditions that exist

in an inclusive branch

Note that an OR gateway join is like

an AND gateway join (synchronization)

except that it ignores incoming sequence flows that are not

enabled

BPMN Series Timer Events – Best Practices and Common Mistakes

© Good e-Learning 2014. All rights reserved.

BP#8: Modeling complex gateways (1/2)

The complex gateway is primarily used to model complex synchronization behavior

There are many patterns that can be performed with a complex gateway, for example:

• typical inclusive gateway behavior (i.e. accepting all active incoming flows)

• batching of multiple tokens

• accepting tokens from some paths but ignoring the tokens from others

Since the gateway looks the same for each of these patterns, it is best practice to use a text annotation to inform the reader about the complex synchronization behavior that is occuring

BPMN Series Timer Events – Best Practices and Common Mistakes

© Good e-Learning 2014. All rights reserved.

BP#8: Modeling complex gateways (2/2)

Require 2 tokens to continue

Require 3 tokens to continue

If you use this text annotation, the process will continue, since there

are two tokens ready at the input of the complex gateway

When using this text annotation, the process will wait for the third token because there are only two tokens ready at the input of the

complex gateway

Without using any text annotation, the process behavior will be unclear

BPMN Series Timer Events – Best Practices and Common Mistakes

© Good e-Learning 2014. All rights reserved.

Boundary Timer Events

Data objects can be connected to ‘item aware elements’ (e.g. activities and events) in two ways:

• by using directed associations between item aware elements and data objects or

• by associating data objects with sequence flows

Whilst the second approach is less complex, it should be avoided because the resulting sequence flow object could be a gateway

Task 1 Task 2

Data Object

Task 1 Task 2

Data Object

BPMN Series Timer Events – Best Practices and Common Mistakes

© Good e-Learning 2014. All rights reserved.

BP#9: Associating data objects with sequence flows (2/2)

A best practice in this scenario is to use directed associations to target activity.

Task 1

Cond A

Cond B

Task 2

Task 3

Data ObjectIt is unclear if a data object is required for Task 2, Task 3 or both.

Task 1

Cond A

Cond B

Task 2

Task 3

Data ObjectIn this diagram it is

clear that the target of data object is task 2

BPMN Series Timer Events – Best Practices and Common Mistakes

© Good e-Learning 2014. All rights reserved.

BP#10: Modeling input and output sets

An input (output) set is a collection of data (documents) that is required to start an activity

A best practice here, if there is more than one input, is to pick a point on the boundary of an activity and ensure that all the inputs that belong to a single input set connect to that point

The same pattern applies when modeling output sets

Review report

Report – Part 1

Report – Part 2

Full report1st

input set

2nd

input set

The activity will be ready to perform as soon one input set is complete.

BPMN Series Timer Events – Best Practices and Common Mistakes

© Good e-Learning 2014. All rights reserved.

Summary

These slides presented four best practices that should help decrease the ambiguity and increase the usefulness of your BPMN diagrams

These best practices can be summarized in the following way:

• Inclusive branches can cause unpredictable behaviors- so use OR gateways in pairs.

• Complex gateway behavior can be configured- so use comments to define their behavior in specific situations

• Make sure you adjust your diagram to present information flows and data sets (collections) in an unambiguous way

BPMN Series Timer Events – Best Practices and Common Mistakes

© Good e-Learning 2014. All rights reserved.

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