Intermediate Event

Introduction

A BPMN 2.0 Intermediate Event represents an event that occurs during the process flow, between the start and end events. It does not initiate or terminate the process, but it alters or influences the process as it progresses. Intermediate Events are used to model interruptions, delays, or triggers that affect the flow of a business process.

Key Points about Intermediate Events

• Visual Representation: A circle with a double border.
• Types of Intermediate Events:
  • Message Intermediate Event: Waits for or sends a message during the process.
  • Timer Intermediate Event: Delays the process for a specified time or until a certain date.
  • Conditional Intermediate Event: Waits for a condition to be met before proceeding.
  • Signal Intermediate Event: Catches or throws a signal that affects the process or other processes.
  • Error Intermediate Event: Handles errors that occur within the process.
  • Escalation Intermediate Event: Represents an escalation that needs to be addressed before continuing.

Placement

• Catch Event: An Intermediate Event that waits for something to happen (e.g., a message or a signal).
• Throw Event: An Intermediate Event that actively triggers something (e.g., sending a message or signal).

Intermediate Events can appear within the normal flow of the process, attached to the boundary of an activity (called a boundary event), or as part of complex processes where specific conditions or events need to be monitored or triggered during the workflow.

An intermediate event, positioned between the start and end points of the process, plays a role in either capturing or dispatching (“throwing”) information. The nature of the intermediate event, whether it is to catch or throw information, can be understood by examining the connecting element within the diagram.

In the diagram, the reception of a message triggers the start of the process. The next task checks if the item is in stock and sends out a confirmation link as soon as the item is available. This act of sending the confirmation link is facilitated by an intermediate event that dispatches the link. The process progresses to order processing only after the confirmation link has been successfully received, resulting in the completion of the order (end event).

Throughout the process, various symbols within the intermediate events signify different triggers that can influence the flow of events. These triggers are messages, timers, errors, compensations, conditional flows, signals, multiple events, escalations, and parallel processes. Each represents a specific type of interaction or condition within the process.

All events with their corresponding symbols