Comprehensive Guide to BPMN Activity Notation

Business Process Model and Notation (BPMN) is a standardized graphical notation used to model business processes clearly and consistently. One of the core elements of BPMN is the Activity, represented by rounded rectangles. Activities represent the work performed within a process and are essential for detailing the steps and tasks that drive a workflow. This guide, based on the provided image, explains BPMN Activity notation in depth, including its types, subtypes, and practical examples, to help beginners and advanced users effectively model processes.

What Are BPMN Activities?

Activities in BPMN represent the work or tasks performed by an organization or individual within a business process. They are depicted as rounded rectangles and serve as the building blocks of a process, illustrating the steps required to achieve a goal. Activities can be either atomic (single, indivisible tasks) or compound (complex tasks broken down into sub-processes). Understanding activities is crucial for creating accurate and actionable BPMN diagrams.

Key characteristics of activities:

• They are a step within the process.
• They can range from simple, manual tasks to complex, automated workflows.
• They can be detailed further using specific notations to indicate the type of work or level of complexity.

Types of BPMN Activities

BPMN activities are categorized into two main types: Tasks and Sub-processes. Below, we explore each type, their subtypes, and their significance.

1. Task

A Task is a simple, atomic activity used when the work performed within the process is not defined at a more detailed level. It represents a single unit of work that cannot be broken down further in the current diagram. Tasks are the most common activity type in BPMN and are depicted as a basic rounded rectangle.

Subtypes of Tasks

BPMN defines several specialized types of tasks, each with a unique icon inside the rounded rectangle to indicate the nature of the work. These subtypes help specify how the task is performed or automated:

• User Task (Person icon, 👤):
  Represents a task performed by a human user, typically interacting with a system or application.
  Example: An employee filling out a leave request form in a company portal (e.g., “Fill-in the Leave Application Form” from the ABC Company leave process).
• Manual Task (Hand icon, ✋):
  Represents a task performed without the aid of any business process automation or application, relying on human effort.
  Example: A warehouse worker manually inspecting a product prototype during manufacturing (e.g., “Review Prototype” at Hello World Manufacturing).
• Service Task (Gear icon, ⚙️):
  Represents an automated task executed by a business process automation tool or service, such as an API or system integration.
  Example: Automatically generating a production plan in a manufacturing system based on a customer order (e.g., “Issue Production Request” at Hello World Manufacturing).
• Send Task (Envelope icon, ✉️):
  Represents a task that sends a message to an external or internal participant, such as an email or notification.
  Example: Notifying a customer via email about product delivery status (e.g., “Inform the Acceptance of Request” in the ABC Company leave process).
• Receive Task (Envelope icon with arrow, ✉️⬅️):
  Represents a task that waits for a message from an external or internal participant.
  Example: Waiting for a customer’s 2D conceptual drawings before starting design work (e.g., “Issue Request” from the Customer lane at Hello World Manufacturing).
• Script Task (Script icon, 📜):
  Represents a task executed by a script or automated code, typically within a business process engine.
  Example: Running a script to validate cost estimates during product development (e.g., “Estimate Cost” at Hello World Manufacturing).
• Reference Task (Up arrow icon, ⬆️):
  Represents a task that references another process or task defined elsewhere, often used for reuse or standardization.
  Example: Referencing a standardized quality check procedure during product verification (e.g., “Verify Product” at Hello World Manufacturing).

Example of Tasks in Action

Consider the Hello World Manufacturing product development process:

• User Task: “Develop 3D Sketch” by a designer using CAD software.
• Manual Task: “Review Prototype” by a team member physically inspecting the prototype.
• Service Task: “Commence Production” automated by a manufacturing system.
• Send Task: “Prepare Invoice” to notify the customer of payment details.
• Receive Task: Waiting for “2D Conceptual Drawings” from the customer.

2. Sub-process

A Sub-process is a compound activity whose details are defined as a flow of other activities, tasks, or sub-processes. It represents a more complex, hierarchical process within the main process. Sub-processes are depicted as a rounded rectangle with a “+” or “−” symbol (expand/collapse indicator) and can be further categorized.

Subtypes of Sub-processes

• Embedded Sub-process (Rounded rectangle with “+” inside):
  Represents a sub-process that is fully dependent on the parent process. It cannot contain pools or lanes and is used to model detailed steps within the same context.
  Example: Within “Develop 3D Sketch” at Hello World Manufacturing, an embedded sub-process could include tasks like “Create Initial Design,” “Run Simulation,” and “Refine Model,” all within the Design Dept lane.
• Reusable Sub-process (Rounded rectangle with “+” inside, often with a border):
  Represents a standalone, reusable process defined separately as another BPMN diagram. It does not depend on the parent process and can be reused across multiple processes.
  Example: A reusable sub-process for “Verify Product” at Hello World Manufacturing, used across different product lines, detailing quality checks, testing, and certification steps.

Example of Sub-processes in Action

In the ABC Company leave application process:

• An Embedded Sub-process could be added to “Evaluate Leave Application,” breaking it down into tasks like “Check Availability,” “Review Policy,” and “Consult Team Leads.”
• A Reusable Sub-process might be “Manage the Application” in the HR lane, reused for other HR processes like vacation approvals or sick leave, defined as a separate diagram with tasks like “Update Records,” “Notify Payroll,” and “Schedule Leave.”

How Activities Fit into BPMN Diagrams

Activities are integral to BPMN diagrams, connecting with other elements like events, gateways, and flows to create a complete process model:

• Events: Activities often follow start events (e.g., “Issue Request” triggering “Develop 3D Sketch”) and precede end events (e.g., “Deliver Products” concluding the process).
• Gateways: Activities can be influenced by decision points, such as “Accept Prototype?” leading to “Place Order” or “Request Change.”
• Sequence Flows: Solid arrows link activities sequentially, showing the order of execution (e.g., “Develop 3D Sketch” → “Prepare Prototype”).
• Message Flows: Activities involving communication (e.g., Send/Receive Tasks) use dashed arrows to show interactions (e.g., customer sending “2D Conceptual Drawings”).

Best Practices for Using BPMN Activities

To effectively model processes using BPMN activities, follow these guidelines:

• Choose the Right Task Type: Use specific task icons (User, Manual, Service, etc.) to clarify how work is performed, improving readability.
• Use Sub-processes for Complexity: Break down complex activities into sub-processes to manage detail without cluttering the main diagram.
• Maintain Consistency: Use consistent naming and notation (e.g., always use “User Task” for human interactions) to ensure clarity.
• Balance Detail and Simplicity: Avoid overcomplicating diagrams with too many sub-processes; use tasks for atomic steps and sub-processes for compound workflows.
• Document Artifacts: Add annotations or data objects (e.g., “Production Plan”) to provide context for activities, enhancing understanding.

Common Pitfalls to Avoid

• Overusing Tasks: Avoid modeling every minor action as a separate task; group related steps into sub-processes for clarity.
• Ignoring Task Types: Using generic tasks instead of specific types (e.g., User, Service) can obscure how work is performed.
• Neglecting Sub-processes: Failing to use sub-processes for complex activities can make diagrams hard to follow.
• Missing Flows: Ensure all activities are connected with sequence or message flows to avoid ambiguity in the process flow.

Practical Examples Across Industries

Here are additional examples of BPMN activities in different contexts:

1. Healthcare – Patient Admission:
   • User Task: “Register Patient” (nurse enters data into a system).
   • Manual Task: “Check Vital Signs” (doctor manually assesses the patient).
   • Service Task: “Schedule Appointment” (automated booking system).
   • Sub-process (Embedded): “Conduct Diagnostic Tests,” including tasks like “Order Blood Test” and “Analyze Results.”
2. Retail – Order Fulfillment:
   • Send Task: “Notify Customer of Order Status” (email confirmation).
   • Receive Task: “Receive Payment” (waiting for customer payment).
   • Sub-process (Reusable): “Pack Order,” reused across different product lines, detailing tasks like “Select Items,” “Wrap Products,” and “Label Package.”
3. Finance – Loan Approval:
   • User Task: “Review Loan Application” (loan officer evaluates documents).
   • Service Task: “Run Credit Check” (automated system checks credit score).
   • Sub-process (Embedded): “Verify Income,” including “Request Pay Stubs” and “Validate Employment.”

Conclusion

BPMN Activity notation, represented by rounded rectangles, is a cornerstone of process modeling, enabling detailed representation of work within a business process. Tasks (atomic, with subtypes like User, Manual, Service) and sub-processes (compound, including embedded and reusable) provide flexibility to model both simple and complex workflows. By understanding and applying these notations—using the Hello World Manufacturing, ABC Company, or other examples—you can create clear, actionable BPMN diagrams to document, analyze, and optimize processes. Whether you’re modeling product development, leave requests, or customer service, mastering BPMN activities ensures your diagrams are precise, communicative, and aligned with industry standards.

This guide, based on the provided image, equips you with the knowledge to effectively use BPMN activities, offering practical examples and best practices for real-world applications.