This pattern allows defining time lags between two activities; i.e., to express a minimum or maximum temporal distance between them.

Also known as

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Problem

A time lag between two discrete events needs to be obeyed. Respective events occur, for example, when instantiating or completing a process instance, when reaching a milestone in a process instance, or when triggering specific events inside an activity.

Design Choices

Solution

A time constraint is introduced between two events.

Again timers can be used to realize this pattern at run-time (cf. TP1). Additionally, an observer, monitoring external events and notifying the time management component, is required.

Context

The mechanism evaluating the constraint (i.e., starting the timer) needs to be able to access the value of the time lag prior to its activation (i.e., the occurrence of the start event) in order to start the respective timer.

Examples

• The time lag between the delivery of all parts (milestone) and the assembly of the car’s chassis (milestone) should be no more than 2 hours (e.g. just-in-time production) (Design Choices D[b]).
• The time lag between two heavy maintenance visits of an aircraft is 4-5 years (Design Choice D[c])

Related Patterns

• TP1 – Time Lags between Activities
• TP2 – Durations

Animation

Product Evaluation

We differentiate between supported, partially supported, not supported and not specified.
If an evaluation object provides support for the particular pattern the supported design choices are listed. If the pattern is only partially supported (e.g., by a work-around) this is indicated by the additional label "*" and if support is not specified this is indicated by the label "?". Missing support is labeled with "-".