Figure: Control Flow Options
Control flow options define the split, join and loop behavior around the activity. For details on the concept and use cases of control flow used in Stardust, refer to chapter Control Flow in the Concepts section.
Figure: Control Flow Options
In the Stardust Eclipse Modeler, the control flow selected for an activity is represented as a diamond-shaped box, called gateway. The control flow behavior is visible via the icon inside a gateway, representing AND, XOR or OR split or join types. Find details and screenshots of specific gateways in the following sections.
In some cases you do not see the type of the gateway from the diagram alone, for example if a gateway is a split gateway of the preceding or the join gateway of the next activity. Then use the gateways tooltip. Move the mouse over the gateway to display the name of the activity and the type of control flow.
The Join behavior specifies the runtime behavior in case of multiple transitions from the predecessor activity leading to the chosen activity. The following options are offered:
If an activity is joined with the XOR option, one incoming transition is processed the chosen activity is instantiated. If multiple incoming transitions are processed at runtime the chosen activity is instantiated multiple times. XOR joins are displayed by an empty gateway sign.
Figure: XOR Join Icon
If an activity is joined with the AND option, all incoming transitions are required to be processed for the execution of the activity. An AND-join is marked by a gateway sign with a plus icon in the middle.
Figure: AND Join Icon
If an activity is joined with the OR option, it is waiting for all incoming transitions that are evaluated to true. OR joins are displayed as a gateway sign with a bold circle inside.
Figure: OR Join Icon
Apart from the property page settings you can change the join behavior of an activity in the diagram directly. Right-click the activity and select Join Behavior. Choose the desired join behavior for the activity.
Figure: Changing the Join Behavior
The Split behavior specifies how multiple transitions to the following activities are to be executed. The following options are provided:
If an activity is split with the XOR option, only one of the multiple transitions to the following activities is executed. Only the first transition is instantiated that condition evaluates to true. XOR splits are marked by an empty gateway sign.
Figure: XOR Split Icon
If an activity is split with the AND option, all outgoing transitions to the following activities are executed.
Each transition is evaluated and followed if the evaluation results to true. An AND-split is marked by a gateway sign with a plus icon in the middle.
Figure: AND Split Icon
If an activity is split with the OR option, each of the multiple transitions to the following activities is executed and, in case it evaluates to true, instantiated. OR splits are marked by a gateway sign with a bold circle inside.
Figure: OR Split Icon
Refer to section Inclusive Gateway Usage Example of chapter Control Flow in the Concepts section for an example use case.
Apart from the property page settings you can change the split behavior of an activity in the diagram directly. Right-click the activity and select Split Behavior. Choose the desired split behavior for the activity.
Figure: Changing the Split Behavior
The Loop behavior specifies how an activity is repeated until the loop condition is fulfilled. During the runtime execution of loop activity the specific part of the workflow is repeated.
When an activity enters the loop, one or more instances of the activity are created and performed. On termination of the activity instance, the loop condition is evaluated and based on the result a new activity instance is created. This is repeated until the loop gets terminated and then the subsequent activity is performed, if any.
The option No Loop indicates that the activity is performed exactly once regardless of the evaluation of the condition.
If the option Standard is selected as loop type, you can choose between a While or Repeat loop. In the Loop condition entry field, you can enter the condition.
Currently, the single line format is supported only. The example in the following figure uses the While loop condition:
Figure:While Loop Condition
More elaborate cycles in the model should be modeled explicitly by cycles in the activity/transition graph. See figure below.
Figure: Transition in a Cycle
In this example transition conditions influence the process flow. Please refer to Specifying Transition Conditions.
The Multi Instance loop type specifies that the activity is a multiple instances activity. For details on the concept of multi instances activities as well as the supported activity, application and parameter types, refer to chapter Using Multiple Instance Activities of the Concepts handbook.
You can choose between Sequential
and Parallel processing.
The following data parameter definitions to be used for the multi-instance processing can be set:
Note
Please use the sequential processing type with care. In some cases it might lead to uncompleted processes.
In case of sequential processing, an additional option to limit the transaction batch size is provided. By default, the check box Limit Transaction Batch Size is disabled and all instances are processed in one transaction.
You can configure the number of instances to process in one transaction for sequential multiple instance activities by selecting this checkbox. Now the Maximum Batch Size entry field will be enabled containing the default value 1. Enter a batch size, which should be an integer value specifying the concrete limit. The transaction will be committed after processing of the specified number of instances. A new transaction or activity thread will be started for processing subsequent activity instances and the instance counter and transaction duration timer will be reset to 0.
Figure: Limiting the Transaction Batch Size
The following example uses a multiple instance loop type in a subprocess activity. Formal in and output parameters of the process interface are used to pass each element of a String list.
Figure: Multi Instance Loop Example
Figure: Multi Instance Loop Parameters