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Issue Issue
Trackpoint 24 hours Freight Trackpoint
Notice delivered Notice Freight
[more Wait 24 Hours Delivered
Trackpoints] [else]
Initiate
Shipment
more Status Inquiry Initiate
Trackpoints Shipment
Log Status Inquiry
Trackpoint
Log Trackpoint Order Entry
Order Entry
Create
Acceptance
Certificate
Create
Acceptance
Certificate

Fig. 13.7 Side-by-side BPMN diagram and corresponding YAWL net

change has been introduced so that the same example can be used to illustrate the
mapping of data-driven and of event-based decision gateways.
This example highlights the one-to-one correspondences between BPMN and
YAWL. Each task and each event in the BPMN diagram has a corresponding task
in the YAWL net. Similarly, each gateway is mapped to a decorator. For exam-
ple, the XOR-split and XOR-join gateways surrounding the Issue Trackpoint Notice
task become XOR-split and XOR-merge decorators in the corresponding YAWL
net, while the AND-join just before task Create Acceptance Certificate becomes an
AND-join decorator attached to the corresponding task in the YAWL net.
In some cases, empty tasks need to be inserted in the YAWL net for the purpose
of holding decorators that cannot be attached to other nonempty tasks. For example,
the initial AND-split in the BPMN diagram is mapped to an AND-split decorator
attached to an empty YAWL task. Indeed, as this AND-split decorator is needed
right at the start of the net, it is not possible to attach it to any of the nonempty tasks
in the net. Another scenario where empty tasks need to be introduced in a YAWL
net in order to hold a decorator is when multiple gateways in the original BPMN
diagram are chained together. This scenario is illustrated in Fig. 13.8, which shows
a fragment of a BPMN diagram and the corresponding YAWL fragment. The YAWL
fragment contains an empty task with an AND-split decorator. This AND-split
decorator cannot be attached to the previous task (Prepare Transportation Quote)
because this previous task already has an XOR-split decorator.