BPMN v1.1 - Loops

title

BPMN 2.0 BPMN v1.1 - Loops

author

Bernard Szlachta (NobleProg Ltd)

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