Start Event
A Start Event indicates where a process begins. It represents the triggering point that initiates the flow of activities in a business process. Every process must have at least one Start Event to define its entry point. For example, a customer clicking "Submit Order" on a website triggers the start event of the order fulfillment process.
What is a Start Event?
A Start Event marks the beginning of a process flow. When a process is instantiated, execution begins at a Start Event and proceeds along the outgoing sequence flow. The None Start Event (shown as a thin circle) is the simplest form-it indicates that the process starts without any specific trigger condition.
Visual Representation
The Start Event is depicted as a thin single-line circle (as opposed to End Events which have thick borders). When no trigger is specified, the circle is empty inside. Triggered Start Events contain a marker icon indicating the trigger type (message, timer, signal, etc.).
Key Characteristics
- Single outgoing flow: A Start Event has exactly one outgoing sequence flow and no incoming flows
- Process instantiation: Each time a Start Event is triggered, a new process instance is created
- Multiple Start Events: A process can have multiple Start Events, each representing a different way to initiate the process
- Top-level only: Start Events appear at the process level, not inside sub-processes (which use None Start Events)
See it in action
Max encounters his first BPMN diagram starting with a start event
Read: The Shoe Shop →Common mistake
Having multiple None Start Events in the same process level. If a process has multiple start events, each should have a different trigger (message, timer, signal) to clarify which one initiates the instance.
How it connects
Trigger Variants
Start Event can be triggered by different mechanisms.
Message Start Event
message trigger
Timer Start Event
timer trigger
Signal Start Event
signal trigger
Conditional Start Event
conditional trigger
Error Start Event
error trigger
Escalation Start Event
escalation trigger
Compensation Start Event
compensation trigger
Multiple Start Event
multiple trigger
Parallel Multiple Start Event
parallel-multiple trigger
Common Use Cases
Manual Process Initiation
A user manually starts a process, such as submitting a request form or clicking a "Start" button in an application.
Default Entry Point
When a process can begin in multiple ways, the None Start Event serves as the default or fallback entry point.
Sub-Process Beginning
Inside embedded sub-processes, a None Start Event marks where execution continues when the sub-process is entered.
Frequently Asked Questions
Related BPMN Elements
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