Some interactions may be time-critical. The information may have no value if it is too old or a response may be required quickly. In these cases the analyst may express that certain interactions have time constraints.
A single interaction may need to be completed in a certain amount of time. At the Brasil/Yugoslav Zoo, if any staff member notices the tigers are hungry, they must alert a feeder within 10 minutes. (Hungry tigers can get pretty ugly.) Figure 1 expresses this constraint.
Figure 1. Interaction constrained to be quick
A set or series of interactions may need to be completed in a certain amount of time. Figure 2 expresses that a feeder must feed the tigers within 30 minutes of a staff member noticing the tigers are hungry.
Figure 2. Sequence of interactions constrained to be quick
Although not likely to occur, real time constraints may be arbitrarily complex. For instance, the following are allowed:
Go to Continuous Interactions Interactions Within an Object Class