Delays

The delay clause is used to create a delayed topic view. This means that changes to the source topics are reflected in the reference topics after a predetermined, fixed delay of your choice.

A delay affects the following:

  • topic values

  • topic additions

  • topic removals

Hence, the reference topics will reflect the structure of the source topics as they were at the earlier point in time (pre delay).
It is an optional feature.

Using delays

The delay clause has the form: delay by <duration>, where duration is a positive integer followed by a time unit which is seconds, minutes, or hours.

For example, the following topic view specification maps all topics below the path a to reference topics below the path b, with a five minute update delay.

map ?a// to b/<path(1)> delay by 5 minutes

Views with delay clauses initially create reference topics in an unpublished state.
The topics are only published once the delay time has passed.

An unpublished reference topic prevents a lower priority topic view from creating a reference topic with the same path.