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Event description

An Event is an object emitted by Taipy to notify about change in the system. It serves as a notification mechanism for any changes occurring within Taipy, particularly those related to the Scenario and Data Management. It is a crucial part of the system that allows tracking and responding to changes in the various entities managed by Taipy, such as data nodes, jobs, and scenarios.

Event attributes

An Event object is composed of several key attributes that describe what happened, the type of operation performed, the entity concerned and its type, and other contextual details.

1. entity_type

  • Type: EventEntityType (Enum)

  • Description: Specifies the type of entity that has undergone a change. This attribute helps identify the nature of the object affected. The possible entity types are:

    • CYCLE
    • SCENARIO
    • SEQUENCE
    • TASK
    • DATA_NODE
    • JOB
    • SUBMISSION

2. operation

  • Type: EventOperation (Enum)

  • Description: Indicates the type of operation performed. The operation attribute is essential for understanding the nature of the change. The possible operations are:

    • CREATION - An entity has been created.
    • UPDATE - An entity has been updated.
    • DELETION - An entity has been deleted.
    • SUBMISSION - An entity has been submitted for processing.

3. entity_id

  • Type: str
  • Description: The unique identifier for the entity that has been changed. This ID allows you to precisely identify which object in the system the event refers to.

4. attribute_name

  • Type: str
  • Description: The name of the specific attribute that has been changed within the entity. This attribute is only relevant for UPDATE operations, where a specific field of an entity has been modified.

5. attribute_value

  • Type: Any
  • Description: The new value of the changed attribute. Like attribute_name, this only applies to UPDATE operations.

6. metadata

  • Type: dict
  • Description: A dictionary containing additional metadata about the source of the event. This can include context-specific information that provides more insight into the event's origin or purpose.

7. creation_date

  • Type: datetime
  • Description: The exact date and time the event was created.

Usage and example

Scenario creation event

For example, when a scenario is created, an event is emitted with the following attributes:

Events are particularly useful when you want to:

  • Update the user interface (e.g., update a list of scenarios when a new one is created)
  • Trigger an action (e.g., automatically submit a scenario when its input data is updated)
  • Notify end-users (e.g., send a GUI notification to all users when a job fails)
  • etc.