The process instantiation, that is, patterns of times and quantities used for generating process instances, can be configured using process instantiation plans or object attributes. If both options are used, the process instances created with process instantiation plans have priority.
General
Process instances are generated using the Schedule model by assigning the model to start objects (events, or functions or rules in the case of BPMN diagrams). Assignment to functions and rules enables process instantiation plans to be used in model types for which start events are not required, such as Business process diagrams, for example. During the simulation run, the process instances are generated at the relevant objects in accordance with the assigned schedule and the start and end times of the simulation. If the simulation time period has been defined with a duration rather than with start and end times, the current date of the simulation run is used as the start time of the simulation run and the end time is calculated on the basis of the start time and the duration. If the Frequency attribute of an event or function has been specified and a process instantiation plan has also been assigned, the process instantiation plan takes priority over the attribute specified for the event.
ARIS models
Process instances are generated by start events. The creation can be controlled using process instantiation plans and also using the attributes of the Frequency attribute type group. They specify how often the process is to be started in the relevant time period. The attributes Day, Week, Month, and Year are available (a month is based on 30 days, a year on 365 days). The input is an integer greater than or equal to 0. By default, one process instance per day is set. If 0 is entered as a value, no process instance is generated. If multiple values have been entered, the value for the shorter interval takes precedence, for example, Frequency, daily has priority over Frequency, weekly.
Example
If you enter 1000 for Frequency, daily, the process is generated once every 86 seconds (86400 sec./day divided by 1000 recurrences/day = 86.4 sec./recurrence, rounded: 86 sec./recurrence). If the simulation covers one day, a total of 1005 processes are instantiated (86400 sec./day divided by 86 sec./recurrence = 1004.65 recurrences/day, rounded: 1005 recurrences/day).
If multiple start events that are linked by an AND rule are used, they must be synchronized. This ensures that process folders with identical process number are generated and that they are joined at the AND rule. The process instances are started at equal intervals during the simulation time period and the number of process instances to be started per simulation run is calculated proportionally.
Start events can be synchronized in event diagrams and EPCs. In event diagrams, occurrences of various start events can be assigned to a common start event. The settings of the common start event are used for process instantiation. If an event diagram is used, the diagram is assigned to the individual start events of the EPC. Similarly, an EPC can be used to synchronize start events.
BPMN diagrams
Process instances are generated at start objects of the process model.
Invalid configuration of start objects
If at least one start event and one flow object do not have an incoming sequence flow (except for compensation activities and certain intermediate events), the simulation cannot be started.
Implicit start events
Processes can be started at start events, activities or gateways. If several flow objects exist without an incoming sequence flow and there is no start event, an implicit start event is used to create process instances for these objects. This applies particularly to objects and processes that have been assigned to processes or subprocesses.
Multiple start events
Start events are independent of each other. If multiple start events exist, a process instance is generated whenever any of the start events is triggered.
Simple time-based process instantiation
Process instances can be generated at different object types. There are different ways to control time-based process instantiation depending on the object type:
Start events
If the process model has a start event of the Timer type ( BPMN > attribute type group Trigger/Result attribute) and the Time cycle attribute has been specified (BPMN > Timer attribute group), the processes are instantiated according to this period. Alternatively, you can define the time using the Frequency attribute group. By default, one process instance per day is set. If 0 is entered as a value, no process instance is generated. Attributes with short intervals have precedence over attributes with long intervals. If the Time cycle attribute has been specified, it has priority over the Frequency attribute. In order for the attribute to be interpretable during the simulation, a time span must be specified in P[n]Y[n]M[n]DT[n]H[n]M[n]S format, conforming to ISO 8601. In this context, the following applies: P = indication that a period follows; Y = years; M = months; D = days; T = separator between date/time; H = hours; M = minutes, and S =seconds. [n] indicates the numerical value in each case. Example: P6DT5H corresponds to 6 days and 5 hours.
Activities
The time is defined via the Frequency attribute group. By default, one process instance per day is set. If 0 is entered as a value, no process instance is generated. Attributes with short intervals have precedence over attributes with long intervals.
Gateways
Simple time-based process instantiation is not possible at gateways. If a gateway is used as a start object, a process instance is not generated.