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submission task and different people perform the approval task. To address
this issue, the authors propose predicates to specify inter-instance workflow
constraints and adapt consistency checking such that a historical record of
task assignments is kept and consulted when making assignment decisions. In
the following, we elaborate the general approach.
4.1 Static User/Role-task Assignment
The approach proposed in [10] uses advance planning of user/role-task as-
signment so that run-time assignments can be performed more quickly. The
planning phase consists of finding all potential assignments given the con-
straints and ensures that assignments can be consistently made such that a
workflow can complete. Example 3 illustrates an example.
Example 3.
Figure 2 shows a research paper review process consisting of three
tasks.
T
2
: Review
paper
T
1
: Submit
Paper
T
2
: Review
paper
T
3
: Issue
Check
Authorized Role:
Researcher
Authorized Role:
Reviewer
T
2
: Review
paper
Authorized Role:
Reviewer
Fig. 2.
Example Workflow with Constraints
Task
T
1
is the paper submission task. Task
T
2
is the paper review task
which needs to be performed by three separate members of the reviewer role.
Task
T
3
is the acceptance decision task. It is performed by a member of the
reviewer role but the member can not have performed task
T
2
.Ofcourse,
neither
T
2
or
T
3
can be performed by the person who performed task
T
1
.
The approach in [11] assesses whether all tasks can successfully be executed
given various assignment options. Figure 3 shows how assignment of user
U
1
impacts assignment to an instance of task
T
2
impacts the workflow.
While in this simple example, it is very easy to see that there must be at
least four members of the review role to successfully accomplish the workflow,
much more complex scenarios with more tasks, user membership in multiple
roles and additional constraints are the norm and the process of planning by
