What is a Start Event in BPMN?

A Start Event is a BPMN element that indicates where a process begins. It is represented by a thin circle and marks the point where process execution starts. Every BPMN process requires at least one Start Event.

When should I use a Start Event?

Use a Start Event at the beginning of every process to define the entry point. Use a None Start Event when the process is triggered manually or when no specific trigger condition applies. Use triggered variants (Message, Timer, Signal) when the process should start automatically based on external events.

How is the Start Event different from related elements?

The Start Event (thin circle) begins a process, while the End Event (thick circle) terminates it. Triggered Start Events like Message or Timer Start Events wait for specific conditions before instantiating the process, whereas None Start Events can be triggered at any time.

What is a Start Event in BPMN?

A Start Event is a BPMN element that indicates where a process begins. It is represented by a thin circle and marks the point where process execution starts. Every BPMN process requires at least one Start Event.

When should I use a Start Event?

Use a Start Event at the beginning of every process to define the entry point. Use a None Start Event when the process is triggered manually or when no specific trigger condition applies. Use triggered variants (Message, Timer, Signal) when the process should start automatically based on external events.

How is the Start Event different from related elements?

The Start Event (thin circle) begins a process, while the End Event (thick circle) terminates it. Triggered Start Events like Message or Timer Start Events wait for specific conditions before instantiating the process, whereas None Start Events can be triggered at any time.

events

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.

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)

Trigger Variants

Start Event can be triggered by different mechanisms. Each variant uses a specific icon marker to indicate its trigger type.

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

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