A predicate is an algorithmic modification to a set of
nodes/resources represented by a tag.
For example, given a tag web_array the following would be
possible predicates.
web_array[10] grab 10 nodes
web_array[1%] grabs 1% of the nodes in the
array
web_array[random] grab a random selection of
nodes
It should also be noted that the predicates should be
deterministic unless it's clear that it's not (like random). The
condition is that the resource model does not change between
invocations. Perhaps even more fine grain is that any nodes
identified in a pervious run are attempted first (queried from the
resource model) and only if they don't match exactly are new ones
replenished.
Alex-SF