Despite advances in the eld of work ow exibility, there is still insu cient support for dealing with unforeseen exceptions. In particular, it is challenging to nd a solution which preserves the intent of the process as much as possible when such exceptions are encountered. This challenge can be alleviated by making the connection between a process and its objectives more explicit. This paper presents a demo illustrating the blended work ow approach where two speci cations are fused together, a \classic" process model and a goal model. End users are guided by the process model but may deviate from this model whenever unexpected situations are encountered. The two models involved provide views on the process and the demo shows how one can switch between these views and how they are kept consistent by the blended work ow engine. A simple example involving the making of a doctor's appointment illustrates the potential advantages of the proposed approach to both researchers and developers.
The two speci cations are consistent from a semantic point of view: any work ow instance that is executing according to one of the speci cations can continue executing according to the other. Therefore each view can present the current state of the work ow instance to end users, who can switch between the two views without having to redo any of the work they have done while using the other view. However, it is possible to produce more information using the goal-based speci cation, so that additional knowledge that may be useful when dealing with unexpected situations can be acquired. Additionally, it is possible to relax some restrictions when executing according to the goal view or to skip the execution of activities in the activity view.
episodes String nPaamtieen(tkey) p1atient * Int nuEmpbiesro(dkeey) Int age (key) Date reserveDate Bool heartProblems Bool checkin episode Bool checkout (key) 1 1 episode (key) IInntt hweeiPiggahhtttient Data1 patientData StriMngeddiecsacl1rRipetmipoonerdticalReport int bloodPressure String physicalCondition medicalPrescription 1 0..1 episode (key)
Medical
Prescription String description 1medicalPrescription
(key) * prescriptionMedication Prescription
Medication Int number (key) String name Int quantity bool heartImpact
Figure 1 presents the data model for a Doctor Appointment work ow speci cation. The creation of a work ow instance corresponds to the creation of an Episode instance and its association to an existing Patient instance. The workow instance progresses by creating instances of the other entities. Eventually a Medical Report will be written and the patient checks out.
Figure 2 presents the activity-based speci cation of the Doctor Appointment example. The speci cation follows a typical BPMN4-like activity-based specication enriched with pre- and post-conditions, denoted respectively by PRE and POS. For each activity, its pre- and post-conditions describe what should be the data model state immediately before and after the execution of the activity, respectively. An activity-based speci cation can execute in an activity engine in isolation, ignoring its set of pre- and post-conditions, but pre- and post-conditions are necessary for the blended work ow to keep both views synchronized, as we shall show in the demo.
The speci cation shows that the Booking activity creates an instance of Episode and sets its reserveDate attribute. Note that the creation of an Episode instance requires a Patient instance and a value for the number attribute, which 4 http://www.bpmn.org/
PRE: episode is DEF POS: (patientData.height is DEF) AND (patientData.weight is DEF))
Col ect Physical
Data Col ect Medical
Data
PRE: episode is DEF POS: (patientData.bloddPressure is DEF) ANF (patientData.physicalCondition is DEF))
patient data medical report
episode Doctor Appointment
Checkout
PRE: (episode is DEF) AND (patientData.bloodPressure is DEF) POS: (medicalReport.description is DEF)
PRE: (episode is DEF) AND (medicalReport.description is DEF) POS: (episode.checkout is DEF) patient list episode
episode Booking
CheckIn POS: (episode is DEF) AND (episode.reserveDate is DEF)
PRE: episode.reserveDate == TODAY
POS: (episode.checkin is DEF) constitute the key attributes of Episode. As another example, note that the execution of Collect Medical Data only requires an instance of Episode. This relaxed restriction occurs because the blended work ow allows activities to be skipped. In this case it would be possible to skip the Booking and Checkin activities, but to execute Collect Medical Data if an Episode instance is created.
AC: today == reserved SC: checkin = TRUE CT: Patient Data AC: episode.checkin Obtain Patient Data Checkin Patient
Physical
Data
CT: Patient Data SC: (height is DEF) AND (weight is DEF) CT: Episode Process
Medical Appointment
Medication Restriction
Patient
and have activation conditions (AC), which should hold true to allow the goal to
Medical Prescription
Add Prescription Medication
become active, and success conditions (SC), which de ne when a goal is achieved. To achieve a goal it is also necessary that all its sub-goals have succeeded. Additionally, a goal has a context (CT) that represents the data model entity which is the root of its condition's evaluation. A maintain goal describes a data model invariant.
The achievement goal Write Medical Report has the Medical Report entity as context, and requires both an Episode instance and a value for the patient's blood pressure to become active. Upon the goal achievement, the description attribute is de ned. The maintain goal Heart Medication Restriction states that it is not possible to prescribe drugs that may adversely impact the hearts of patients with heart problems.
When executing a work ow instance in the activity view end users can: (
When executing a work ow instance in the goal view end users can: (
In this section we describe the demo script and its objectives. For a screen-cast please visit URL: http://www.youtube.com/watch?v=Anb4kuXtBgc. The tool does not include a worklist manager that assigns workitems to users based on their roles because it is not relevant for the blended work ow proof of concept. Therefore in the demo the doctor is able to execute any workitem, either goal or activity.
Second Opinion case
1. Start a Doctor Appointment process for Patient Davide Passinhas;
2. In the activity view, execute all activities until Doctor Appointment activity
is enabled;
3. An unexpected situation occurs: during the Doctor Appointment activity
the patient's condition deteriorates, and the doctor decides to measure his
blood pressure again: (
Urgency case 1. Start a Doctor Appointment process for Patient David Martinho; 2. The Booking activity is executed and the reservedDate is set for 10 days later; 3. Due to urgency of the patient's condition, the patient requires an examination by the doctor before the reserveDate but the Checkin activity is not enabled for execution; 4. The doctor switches to the goal view, activates the Checkin Patient goal and overrides the goal's activate condition, 'today == reserveDate', so that the goal can become enabled; 5. The doctor executes the Checkin Patient goal. The blended work ow engine automatically completes the Checkin activity and enables activities Collect Physical Data and Collect Medical Data; 6. In the activity view Collect Physical Data and Collect Medical Data activities are skipped by the doctor, due to the urgency; 7. The doctor executes the pre-activity in the Doctor Appointment activity to ll in the missing data, the blood pressure data, and continues execution.
Passinhas et al.
The current version of the tool is a second prototype that extends a rst prototype [3] implemented one year ago. It was implemented in JAVA using the FenixFramework5 for the domain speci cation and persistency, Vaadin6 for the user interfaces, and the YAWL [4] engine to execute the activity speci cation. The code is publicly available in a GitHub repository7. 3
The research was partially supported by the Portuguese Foundation for Science and Technology, FCT-MCTES (INESC-ID multiannual funding) through the PIDDAC Program funds. 5 https://fenix-ashes.ist.utl.pt/trac/fenix-framework 6 https://vaadin.com/home 7 https://github.com/socialsoftware/blended-work ow