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4.2 Event Logs 101

Fig. 4.3 Standard transactional life-cycle model

• # time (e) is the timestamp of event e.
• # resource (e) is the resource associated to event e.
• # trans (e) is the transaction type associated to event e, examples are schedule, start,
complete, and suspend.
These are just examples. None of these attributes is mandatory. However, for these
standard attributes we will assume some conventions. For example, timestamps
should be nondescending in the event log. Moreover, we assume a time domain T ,
i.e., # time (e) ∈ T for any e ∈ E . The transaction type attribute # trans (e) refers to the
life-cycle of activities. In most situations, activities take time. Therefore, events may
point out for example the start or completion of activities. In this book, we assume
the transactional life-cycle model showninFig. 4.3.
Figure 4.4 shows some examples to explain the life-cycle model. The life-cycles
of five activity instances are shown: a, b, c, d, and e. a is first scheduled for execu-
tion (i.e., an event e 1 with # trans (e 1 ) = schedule and # activity (e 1 ) = a occurs), then
the activity is assigned to a resource (i.e., an event e 2 with # trans (e 2 ) = assign and
# activity (e 2 ) = a occurs). Later the activity is started by this resource, and finally the
activity completes. Note that four events were recorded for this activity instance.
Activity instance b has seven events associated to it. Compared to a the activity is
reassigned (i.e., the resource that is supposed to execute the activity is changed),
suspended (temporarily halted), and resumed. Of course it is possible to skip stages
in the transactional life-cycle model, because events are not recorded or because
certain steps are not necessary. Activity instance d in Fig. 4.4 has just two events;
e just one, i.e., for e only the completion of the activity instance is recorded. Transac-
tion type “autoskip” refers to an action by the system bypassing the activity. Trans-
action type “manualskip” refers to resource initiated skipping. Transaction types
“abort_activity” and “abort_case” correspond to aborting the activity or the whole
case. A “withdraw” event signals the situation in which the activity is canceled be-
fore it was started. Figure 4.3 shows all transaction types, their enabling, and their
effect. For example, according to the transactional life-cycle model, “abort_activity”
is only possible when the activity instance is running (i.e., started, suspended, or re-
sumed).