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Chapter 11
The Worklet Service

Michael Adams

11.1 Introduction

This chapter discusses the implementation and use of the Worklet Service (a
conceptual overview of the service can be found in Chaps. 4 and 5). The Worklet
Service has been implemented as a YAWL Custom Service (cf. Chap. 7). In the
discussion that follows, a reference to the “Worklet Service” applies to the entire
Custom Service, while a reference to the “Selection Service” or the “Exception
Service” applies to that particular subcomponent of the service.
All of the worklet process models in this chapter are expressed using YAWL nota-
tion – the language is used to model static YAWL processes, and the worklets used
both for selection and exception compensations – thus, all worklet specifications are
examples of standard, complete YAWL process models.

11.2 Service Overview

The Worklet Service comprises two discrete but complementary subservices: a
Selection Service, which enables dynamic flexibility for process instances, and an
Exception Service, which provides facilities to handle both expected and unexpected
process exceptions (i.e., events and occurrences that may happen during the life of
a parent process instance that are not explicitly modeled) at runtime.

11.2.1 The Selection Service

The Selection Service enables flexibility by allowing a process designer to designate
certain work items to each be substituted at runtime with a dynamically selected

M. Adams (B )
Queensland University of Technology, Brisbane, Australia
e-mail: mj.adams@qut.edu.au

A.H.M. ter Hofstede et al. (eds.), Modern Business Process Automation, 291
DOI 10.1007/978-3-642-03121-2 11, c Springer-Verlag Berlin Heidelberg 2010