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BPMN Diagram Symbols

This page will show the different symbols that can be used for modeling a business process and also describe what each symbol means.

An Event is something that happens during the course of a business process.  These 'Events' affect the flow of the process and usually has a trigger or result attached to it.  An Event can start, end and even interrupt the flow.   As you can see, Events look like circles.  The start is one thin line circle, the intermediate is one thin line circle inside of another thin lined circle.  The End is one thick lined circle, it looks like someone color in between the intermediate event with a black pen.  There many types of Events for different purposes.  As you can see below the different ones that are available.

Different Event Action Symbols

The next area that we need to look at is Activities, which is the work that is performed within a business process.

Activity characteristics
  • They can be atomic or non-atomic (compound)
  • They are a task or sub-process
  • They can be performed once or be defined as loops
  • They appear as round rectangles symbols

The activities symbols on the left are the task version of an activity.  The ones on the right side are the activities that represent a sub process that is collapsed into on diagram.  The theory is that when you click into (drill down) the collapsed sub-process, it will expand to show all tasks inside it. There may also be sub-processes inside that sub-process.  The only clear indicator whether a activity is a task or sub-process is the '+' in the square at the bottom of the symbol. 

Task characteristic(s):
  • An atomic activity that is included within a process.
  • Used when work is not broken down into a finer level of detail.
  • Markers or icons can be added to a task to help identify the type that you want the task to emulate.
Sub-Process characteristic(s):
  • Enables a hierarchical process building functionality
  • A compound activity that is included within a process.  This can be broken down into a finer level of detail.
  • A '+' (plus) sign in the lower center of the shape indicates this is a sub-process.
  • Two Type(s)
    • Embedded
    • Independent

The above images show the symbols connected to each other.  The symbols that connect the symbols together is called Connections. There are different types of connections that exist in the diagrams.  These include Sequence Flow, Message Flow, and Association. 

Sequence Flow
is used to show the order that activities will be performed in a process.
Message Flow is used to show the flow of messages between two entities that are prepared to send and receive them.
Association is used to associate data, information and artifacts with flow objects.


Gateways add another dimension to the business process.  Gateways allow for decisions to happen in a process.  This add for XOR, OR AND events to be added to the processes.

The next area that needs to be added to the BPMN library is to add more detail to the process.  This new area is called Artifacts.  Artifacts provide capabilities to show information beyond the basic flow-chart diagram.

Artifact Types
  • Data Objects
  • Groups
  • Annotations

This allows for a simple business process to be documented well.  A simple process is one that happens within one area without any external influences.  The next step is to allow for external influences to come into play.  This can be inter-departmental communication, B2B activity, or even customer communications.  This enhancement is called "Swim lanes".  Swim lanes are used to help partition and/or organize activities.


Pools can represent participants such as a B2B or B2C.  The lanes can represent sub-partitions of objects within a pool.  A sub-partition can be a department, job role, or person

The communication between the patient, receptionist, and doctor is known as Choreography.  Which shows the interaction between two or more business entities.

Next we want to know that we can define processes that are internal to a specific organization, which means it can be contained within a single pool.  This is called an Orchestration.

Orchestration example of an purchase order