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2 The Language: Rationale and Fundamentals 99
it is decided not to investigate the accident further, any instances of the review
situation and determine if investigation required tasks currently running are can-
celed. Regardless of the decision, the process enters the assessment complete
state
Once the process has reached the assessment complete state and any remaining
instances of the interview witness task have completed, the report findings task
can execute and the process can complete execution

Exercise 5. Identify the possible execution traces for each of the following YAWL
processes.

1...2 instances
(d) A B C
(a) A B C
Y X Y
X W
Z
1...3 instances
B C B
(b) A F (e) A F
D E C
E
D
B C
(c) A E
D

Exercise 6. Please provide answers for the following questions.
(a) Identify four distinct ways of passing data between a task instance and the
environment. What are the distinctions between them?
(b) Data passing by reference and value are two common schemes for data handling
in workflows. What are the implications of each strategy?
(c) Identify possible uses for data transformation patterns.

Exercise 7. In a workflow system such as YAWL, work items can be in an offered,
allocated, or started state. As such, there are a number of distribution options for
work items depending on the timing of the various distribution options, for example,
offer, allocate, start results in a work item first being offered to several users and
appearing in their worklist handler in an offered state as shown in the first line (a)
of the diagram below. When one user selects it for allocation, its state changes to
allocated. When (at a later time) the user chooses to start it, its state changes to
started. Which interaction sequences do the other strategies in lines (b), (c), and (d)
correspond to?