Lesson 3: Customization Elements in BPMN: Pools, Swimlanes and Tasks
The third lesson of our BPMN tutorial is dedicated to Pools and Swimlanes. Also, we will describe in more detail the Task element which you are already familiar with.
To show how business process participants interact between each other, BPMN uses Pools and Swimlanes. Usually, in BMP systems a Pool is defined as a container for a process, representing all the process activities and their executors.
Swimlanes are usually used to represent internal business roles and assign duties to all the process participants (for example, chief finance officer, general manager, accountant, etc.) One Pool may contain several Swimlanes (process participants).
Fig.3. Graphical representation of a Pool and Swimlanes
A Swimlane is a rectangular shape that groups all the activities, which a certain user has to perform. In BPMN, Swimlanes can be either vertical or horizontal.
Fig.4. Possible orientation of Swimlanes
If a BPM system describes each process separately (that is to say that each process is modeled on a separate sheet), the Pool usually is not visualized.
We extended our example process (see Figure 5) and now we have two Swimlanes, one of them representing Secretary and the other representing Sales Person. The secretary is responsible for registering and processing the order. Once that is done, the flow goes to the sales person Swimlane. This Swimlane is of the dynamic type, which is rather convenient: it does not specify the exact user, but only represents a certain role (the job position of the responsible employee). There can be several sales people working in a company and either of them can participate in the process.
Fig. 5. “Process request” process
A Swimlane represents the responsibility of the participant who is specified in the Swimlane’s header. For example, Figure 5 shows how the sequence flow goes from the Secretary’s Swimlane to the Sales Person’s Swimlane. The task contained in the first swimlane is for the secretary to complete, while the tasks from the second swimlane are for the sales person.
A process can contain an unlimited number of Swimlanes, so you can include as many process participants as needed. The process flow will determine the sequence, time and executors of all the tasks within the process.
Now let’s continue with the Task element. We have overviewed it in Lesson 1, but we only considered a User Task while in fact BPMN uses several Task types, each one of them with a proper characteristic behavior.
A Task is shown as a rectangular shape with rounded edges, with a single thin line marking its border. A Task type is identified by a specific marker in the Task’s icon.
A User Task is a typical workflow task, executed by a user with the help of other users or software applications. This Task type is distinguished by a person icon.
Fig. 5.1. User Task
Another Task type where a user’s participation is required is Manual Task. Its graphic representation is a rounded rectangle with a thin single line as border. Its distinguishing marker is a hand icon.
Fig. 5.2 Manual Task
A Manual Task is a non-automated task: it is performed by a user and is not controlled by a workflow or BPM software.
Let’s illustrate this type of Task with an example: holding a meeting.
Fig. 5.3. Manual Tasks in business process diagram
Figure 5.3 features a simple example of how a Manual Task can be used in a business process. In our case, it is a process for organizing and holding a meeting. To make our example more understandable, we included only two participants.
Head of the Marketing Department starts the process and fills in the required details: date and time, subject, meeting participants. The marketing specialist receives a task to prepare documents for the meeting. Then the Head of Department actually holds the meeting, and since this activity is not automated, in the process diagram it is represented by a Manual Task. After the meeting, the marketing specialist draws a report and at that point, the process ends.
BPMN also includes Tasks that are executed with no human performer, for example, Scripts.
Fig. 5.4. Script Task
As all the other tasks, a Script is represented as rectangle with rounded corners and has an individual marker in the top left corner.
A Script performs an automated activity by means of the BPM system itself without participation of a human performer. For example, it can process certain data such as a set of numbers introduced by a user. This kind of work is easily done by a computer with no human assistance, providing for fast and accurate results.
However, a Script can do much more than just arithmetic operations – basically, it can represent any automatic activity executed by a BPM system with no human participation.
Figures 5.5 and 5.6 demonstrate different ways to use a Script Task.
Figure 5.5 describes a process where a customer makes an order and the secretary registers it. After that, the system automatically selects a sales person who specializes in the type of merchandise the customer wants to purchase. After that, the system creates a respective task for this sales person, and the process continues.
Figure 5.6 describes a process of collecting the billable hours of the company’s employees. First, each employee is assigned with a task to make a time report of his or her billable hours. Then the system prepares a summary report on all the employees and sends it to the secretary who registers the report. Later, the registered report is used for payroll accounting.
As you may have noticed, Figures 5 and 5.5 feature a BPMN element that we have not yet reviewed. It is called a Sub-Process and is represented as a rectangle with rounded corners and a plus sign in the lower center. You will learn more about this element in the following lessons.
We have reviewed the three most commonly used types of BPMN tasks. You can read more about these and the other types of Tasks in BPMN specification.
To test how well you have learned the study material we offer you to complete the following task. Model the “Vacation Leave” process using the BPMN elements studied in the previous lessons. Make sure to consider all the possible conditions and flows of the process.
For process modeling, we advise you to use ELMA Designer. You can download a free demo version here. After installation, you will need to activate the system (see ELMA quick-start manual for demo version). If you experience any problems with installation or activation of the system, please contact us at firstname.lastname@example.org. We will be happy to help you.
To check yourself, you can download our version of the process diagram.
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