One aspect of the invention is a method for ensuring consistency of a
group, which for example, includes receiving a first list that identifies
objects in the group, and gathering for at least one attribute, the value
of the attribute for each object in the first list. The first list, and
the attribute values gathered in the gathering operation, are stored to
create a first snapshot. This example also includes receiving a second
list that identifies objects that are in the group after at least part of
a task is performed, and the value after at least part of the task is
performed of the at least one attribute for each object identified in the
second list. The second list and the received attribute values are stored
to create a second snapshot, which is compared with the first snapshot.