Page 93 -

80 N. Russell and A. ter Hofstede
Retain familiar: This constraint on a task overrides any other routing strategies
and allows a work item associated with it to be routed to the same user who
undertook a work item associated with a specified preceding task in the same pro-
cess instance. Where the preceding task has been executed several times within
the same process instance (e.g., as part of a loop or it is a multiple instance task),
it is routed to one of the users who undertook a preceding instance of the task.
Four eyes principle: This constraint on a task is essentially the converse of the
Retain familiar constraint. It ensures that the potential users to whom a work
item associated with a task is routed does not include the user who undertook
a work item associated with a nominated preceding task in the same process
instance. Where the preceding task has been executed several times within the
same process instance or is a multiple instance task, it cannot be routed to any of
the users who undertook a preceding instance of the task. Figure 2.38 illustrates
a four eyes constraint for the Book Accommodation task, requiring that it not
be distributed in a given case to the same user who undertook the Lodge Travel
Request task.

Allocation Strategies

Allocation strategies provide a means of selecting one specific user from a range of
users identified by the routing strategy specified for a task. The task is then allocated
to the selected user. There are various means by which this can be done as indicated
below.

Random allocation: This filter ensures that any work items associated with a task
are only ever routed to a single user, where the user is selected from a group of
potential users on a random basis.

Round robin (by time) allocation: This filter ensures that any work items associ-
ated with a task are only ever routed to a single user, where the user is selected
from a group of potential users on a cyclic basis such that each of them execute
work items associated with the task the same number of times (i.e., the distribu-
tion is intended to be equitable). The actual means of selecting the user is based
on the user in the nominated group that executed the task least recently.
Round robin (by least frequency) allocation: This filter operates in a similar
waytothe Round robin (by time) allocation described above; however, rather
than simply selecting the user who executed the task least recently, it actually
involves keeping track of how many times each eligible user has undertaken it
and allocating the task to the person who has executed it least times.
Round robin (by experience) allocation: This filter operates in a similar way to
the Round robin (by least frequency) allocation described above, except that it
selects the user who executed the task most times.