Start Event

What a Start Event Is

A BPMN 2.0 Start Event is the event that triggers or initiates a business process. It marks the point where a process begins and is essential for defining the flow of the process. In BPMN diagrams, the Start Event is represented by a simple circle. It can be triggered by various conditions, such as the arrival of a message, a timer, a condition, or a user action.

Key Points

• Visual Representation: A plain circle.
• Types of Start Events:
  • None Start Event: The process starts when it is launched without a trigger.
  • Message Start Event: The process starts when a message is received.
  • Timer Start Event: The process begins at a specified time or after a set interval.
  • Conditional Start Event: The process starts when a specific condition is met.
  • Signal Start Event: The process starts when a signal is broadcast.
  • Multiple Start Event: The process starts when one of several triggers occurs (or, with Parallel Multiple, when all of them occur).

An Error Start Event is not available on a top-level process: it is only valid as the start of an interrupting event sub-process, where it starts that sub-process when the enclosing process throws an error.

Start Events have no incoming sequence flows, as they always represent the beginning of a process. They set the process in motion and pass control to the next element in the workflow.

A BPMN diagram can feature multiple Start Events. Only the path associated with the specific triggered event will initiate the process instance. For example, consider an order placement process that depends on the mode of receipt, such as through a website, phone, or direct in-person submission. The corresponding start event will initiate the process.

All Events with Their Corresponding Symbols

Related topics

• Events: all event types.
• End Event: where a process ends.