Bernard Szlachta at 02:41, 17 November 2012

2012-11-17T02:41:12Z

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<slideshow style="nobleprog" headingmark="⌘" incmark="…" scaled="false" font="Trebuchet MS" >
;title: BPMN 2.0 BPMN v1.1 - Loops
;author: Bernard Szlachta (NobleProg Ltd)
</slideshow>

== Loops ⌘==
* Standard Loop
** While
** Until
* Multi Instance
** Parallel
** Sequential

== Standard Loop ⌘==
* have a boolean expression that is evaluated after each cycle of the loop
* If the expression is still True, then the loop will continue

;While (TestTime = Before)
* expression is evaluated before the activity is performed
* the activity may not actually be performed

;Until (TestTime = After)
* the activity will be performed at least once.

== Standard Loop Attributes ⌘==
* have a boolean expression that is evaluated ''after each'' cycle of the loop
* If the expression is still True, then the loop will continue
* There are two variations of the loop, which reflect the programming constructs of '''while''' and '''until'''
** '''while''' loop will evaluate the expression before the activity is performed, which means that the activity may not actually be performed
* '''until''' loop will evaluate the expression after the activity has been performed, which means that the activity will be performed at least once

;LoopCondition : Expression
* MUST have a '''boolean''' Expression to be evaluated
* plus the timing when the expression SHALL be evaluated (TestTime)

; LoopCounter : Integer
* used at runtime to count the number of loops and is automatically updated by the process engine
* The LoopCounter attribute MUST be incremented at the start of a loop
* The modeler may use the attribute in the LoopCondition Expression (e.g. LoopCounter <= 12)

;LoopMaximum (0-1) : Integer
* The Maximum an optional attribute that provides is a simple way to add a cap to the number of loops
* This SHALL be added to the Expression defined in the LoopCondition

; TestTime (Before | '''After''') : String
* if '''Before''' the activity begins are equivalent to a programming '''while''' function.
* if '''After''' the activity finishes are equivalent to a programming '''until''' function.

== Multi-Instance Loop Attributes ⌘==
* Multi-Instance loops reflect the programming construct for each
* The loop expression for a Multi-Instance loop is a numeric expression evaluated '''only once''' before the activity is performed
* The result of the expression evaluation will be an integer that will specify the number of times that the activity will be repeated

;MI_Condition : Expression
* MultiInstance Loops MUST have a numeric Expression to be evaluated
* the Expression MUST resolve to an integer

;LoopCounter : Integer
* only applied for Sequential MultiInstance Loops and for processes that are being executed by a process engine
* updated at runtime by a process engine to count the number of loops as they occur
* MUST be incremented at the start of a loop
* Unlike a Standard loop, the modeler does not use this attribute in the MI_Condition Expression, but it can be used for tracking the status of a loop

; MI_Ordering ('''Sequential''' | Parallel) : String
* defines whether the loop instances will be performed sequentially or in parallel
* Sequential MI_Ordering is a more traditional loop (e.g. for i=1 to 10)
* Parallel MI_Ordering is equivalent to multi-instance specifications that other notations, such as UML Activity Diagrams use
* If set to Parallel, the Parallel marker SHALL replace the Loop Marker at the bottom center of the activity shape

=== FlowCondition ⌘===

; MI_FlowCondition (None | One | All | Complex) All : String [Parallel MI_Ordering only]
* This attribute is equivalent to using a Gateway to control the flow past a set of parallel paths.
* '''None''' is the same as '''uncontrolled flow''' (no Gateway) and means that '''all activity instances SHALL generate a token''' that will continue when that instance is completed.
* '''One''' is the same as an '''Exclusive Gateway''' and means that the '''Token SHALL continue past the activity after only one of the activity instances has completed'''
** The activity will continue its other instances, but additional Tokens MUST NOT be passed from the activity.
* '''All''' is the same as a Parallel Gateway and means that the Token SHALL continue past the activity after all of the activity instances have completed.
* '''Complex''' is similar to that of a Complex Gateway. The ComplexMI_FlowCondition attribute will determine the Token flow.

; ComplexMI_FlowCondition (0-1) : Expression [Complex MI_FlowCondition only]
* If the MI_FlowCondition attribute is set to “Complex,” then an Expression Must be entered
* MAY reference Process data
* be evaluated after each iteration of the Activity and SHALL resolve to a boolean
* If the result of the expression evaluation is TRUE, then a Token will be sent down the activity’s outgoing Sequence Flow
* Otherwise, no Token for that iteration will be sent

BPMN v1.1 - Loops - Revision history

Bernard Szlachta at 02:41, 17 November 2012