Guide to BPMN Symbols: How to Read Business Process Model and Notation Diagrams

Understanding the symbols used in Business Process Model Notation (BPMN) is key to learning how to read BPMN diagrams or how to draw a BPMN diagram of your own. Before you start drawing, this guide of all the business process diagram symbols for this standard will help you get started. Read on or jump ahead to one of the following sections:

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Flow Objects in BPMN

Events

In BPMN, events are the things that take place throughout the business process. They are always represented by circles and can include icons within those circles to describe the event with more detail. Your diagrams should also always include a start and end event symbol.

In addition to icons that get more specific about what event is taking place, the circles they’re dropped inside tell you more about when the event is taking place. A thin-lined circle indicates a “start event,” a double-lined circle indicates an “intermediate event,” and a thick-lined circle indicates an “end event.”

So, if the start of your process is triggered by an error, you’d want to use a thin-lined circle with the lightning bolt error symbol inside. If an error is occurring in the middle of your process, you’d use a double-lined circle with the error symbol inside.

Activities

Work takes place between the events in your diagram. That work is described with stylized rectangles to show basic tasks, sub-processes, transactions, and call activity (sometimes referred to as callable process or global task) symbols. 

Gateways

Gateway symbols are diamond-shaped indicators that split or combine your process flow.

Exclusive gateway	This symbol indicates that the process will be evaluated. If it meets certain criteria or conditions, it will move forward through the process flow. If it does not, it will stop or move into a different process. It’s like a decision step in a flowchart.
Event-based gateway	Like an exclusive gateway, this step evaluates whether a specific condition is met or not met. The process will only move forward if and when that condition is met.
Parallel gateway	The parallel gateway doesn’t depend on other conditions being met or events taking place — it simply shows that there are two tasks taking place at the same time.
Inclusive gateway	This gateway brakes the flow into multiple others. One or several of these flows can proceed based upon the evaluation that takes place in this gateway. For example, a customer may place an order where all items are for store pickup, all items are for shipping, or a combination of both. This gateway allows the next steps for both shipping processes and store-pickup processes to be taken.
Exclusive event-based gateway	This gateway operates like the exclusive gateway, rather than waiting for a certain condition to be met, it waits for an event to occur.
Parallel event-based gateway	Like the parallel gateway, this symbol indicates that multiple processes can happen at the same time. However, these processes depend on specific events happening, rather than conditions being met.
Complex gateway	Complex gateways should be used sparingly — only when the process you’re describing is really tangled. Along with this gateway, you need to include a text description so that your diagram users can understand all the detail behind it.

Artifacts

Data Objects

These icons show how data is referenced by, included in, or created by the process you’re describing. It’s important to include data object artifacts when describing your process so that you can understand how other functions within an organization are used by or dependent upon the process you’re describing.

Group

With a dash-dot container, you can organize multiple tasks or processes into a group. This doesn’t change the function of the tasks or processes, but it can help you be more specific about how each of those steps is completed.

Annotation

Annotations are curvy brackets that allow the diagrammer to add additional context to parts of the process. While your diagram should be skimmable and quickly understood, annotations can get into the nitty-gritty so that users who need more information have it all at their fingertips.

Connectors in BPMN

Sequence Flow

Sequence flow arrows show the flow of your BPMN diagram. These are the most basic descriptions of the movement throughout your process and connect to any of the flow objects in your diagram. Sequence flow connectors are simple, solid arrows.

Message Flow

Unlike a sequence diagram that shows how the process moves, message flow arrows simply indicate how information is shared throughout the process. These are represented by a dashed arrow with an unfilled arrowhead.

Association

Association arrows connect artifacts to flow objects so that your diagram users can understand where the additional description or data applies to the process. Associations are shown with dotted lines — no arrowhead included.

Using Swimlanes for BPMN Diagrams

Last, your flow objects, artifacts, and connectors lie on top of a swimlane framework. You may be familiar with swimlane diagrams, which are a type of flowchart that use columns or rows to organize a process. These rows, called swimlanes or pools, are a core part of the structure of BPMN diagrams, too.

🎬 Watch our tutorial video for tips on Gliffy's swimlane functionality: How to Make a Swimlane Diagram

Pools

Pools are a type of division that defines a process or organization. These tend to be broad functions, like “marketing” or “IT” or even between two different companies or entities altogether. If you were making a model of how a restaurant serves a customer, the restaurant and the customer would be their own pools.

Lanes

Lanes are a division that fit within pools to give a more specific definition of who ultimately performs a certain activity. Using the example of the process of eating at a restaurant from above, the customer would be their own pool and the restaurant would be its own pool. However, you could further break down the restaurant pool into lanes like “server” and “kitchen” to be more specific about who within the restaurant is carrying out specific tasks.

What is the Difference Between a Pool and Lane in BPMN?

It’s normal for people to misuse “lane” when they mean “pool” and vise versa. The key difference between a pool and a lane is that pools should be used as the biggest container for your process, while lanes should be specific and detailed within a pool. 

Almost all of the details of your diagram should fit within one pool and that pool can have as many lanes as necessary to clearly depict your process.

What is a Black Box Pool?

A black box pool is a pool within a diagram that doesn’t include any details. It’s not best practice for BPMN diagrams to have multiple detailed pools — it could be a sign that the scope or audience for your diagram is too broad. Further, it’s common for the additional pools in your diagram to be external entities, where you don’t know or control their process.

To create a black box pool, you’d simply use a labeled rectangle. No information would show up within that rectangle, but arrows would flow to and from the black box.

Consider the example of the restaurant process. If you’re the restaurant manager, you likely have some idea of what the customer will do at your restaurant, like making a reservation or opening a bar tab, but you don’t have control over the way in which they go about doing those things. You could map out their process (starting with placing an order and ending with finishing their meal, for example), but this would simply clutter your diagram. What you care about and what you control are purely the events taking place within the restaurant.

Use BPMN Symbols with Gliffy

Ready to put this guide to good use? Save time by simply dragging and dropping the BPMN shapes you need into your diagram. That's all it takes to make awesome BPMN diagrams like this (check out the full BPMN tutorial, too!):

Get started with a free trial of Gliffy in Confluence, or try our online diagramming tool, Gliffy Online. You’ll be able to drag and drop each of these business process diagram symbols to quickly make a BPMN diagram.

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