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11 The Worklet Service 307

Fig. 11.11 Example handler process in the Rules Editor

The Exception Service maintains a set of Ripple-Down Rules that is used to
determine which exlet, if any, to invoke. If there are no rules defined for a cer-
tain exception type in the rule set for a specification, the exception event is simply
ignored by the service. Thus rules are needed only for those exception events that
are desired to be handled for a particular task and/or specification.
An example of a definition of an exlet in the Rules Editor can be seen in
Fig. 11.11 (see Sect. 11.10 for more details regarding the Rules Editor and its use).
On the left of the graphical editor is the set of primitives that may be used to
construct an exlet (see Chap. 5 for a detailed description of each primitive and its
effects). The available primitives (reading left-to-right, top-to-bottom) are:

Remove Work Item, Case, All Cases
Suspend Work Item, Case, All Cases
Continue Work Item, Case, All Cases
Restart Work Item
Force Complete Work Item
Force Fail Work Item
Compensate
To demonstrate a few of the major features of the Exception Service, this section
will use a small portion of the Carrier Appointment subnet of the Order Fulfill-
ment process, specifically the branch that deals with the delivery of a single package
(Fig. 11.12).