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5 Exception Handling 161
compensation worklet

cancel stadium book theatre advise fans
ChangeToMidVenue

ItemPreConstraint
C exlets
C

C
C

‘parent’ process

book stadium sell tickets do show
OrganiseConcert

Fig. 5.6 Process – exlet – worklet hierarchy

to at any time, as can the rules base used, including while the parent process is
executing.
The Selection and Exception subservices can be used in combination within
particular case instances to achieve dynamic flexibility and exception handling
simultaneously. The Worklet Service is extremely adaptable and multifaceted, and
allows a designer to provide tailor-made solutions to runtime process exceptions and
requirements for flexibility.

5.4.2 Architectural Overview

This section provides a brief overview of the technical attributes and structure of the
Worklet Service (for a much more detailed treatment, see Chap. 11). The service is
constructed as a web service and so consists of a number of J2EE classes and servlet
pages, organizedin a series of packages, for deployment via a servlet container (such
as Apache Tomcat).
The external architecture of the Worklet Service is shown in Fig. 5.7. The enti-
ties “Worklet Specs,” “Rules,” and “Logs” comprise the Worklet Repository.The
service uses the repository to store rule sets, compensatory worklet specifications