# Package org.apache.tinkerpop.gremlin.process.traversal.step.util.event

- Interface Summary
  Interface | Description
  --- | ---
  CallbackRegistry<E extends Event> |
  Event | A representation of some action that occurs on a `Graph` for a `Traversal`.
  EventCallback<E extends Event> | A `Consumer` function definition for consuming `Event` objects raised from `Step` objects at the time of execution.
  MutationListener | Interface for a listener to `EventStrategy` change events.

- Class Summary
  Class | Description
  --- | ---
  ConsoleMutationListener | An example listener that writes a message to the console for each event that fires from the graph.
  Event.EdgeAddedEvent | Represents an action where an `Edge` is added to the `Graph`.
  Event.EdgePropertyChangedEvent | Represents an action where an `Edge` `Property` is added/modified.
  Event.EdgePropertyRemovedEvent | Represents an action where an `Edge` `Property` is removed.
  Event.EdgeRemovedEvent | Represents an action where an `Edge` is removed from the `Graph`.
  Event.ElementPropertyChangedEvent | A base class for `Property` mutation events.
  Event.ElementPropertyEvent | A base class for `Property` mutation events.
  Event.VertexAddedEvent | Represents an action where a `Vertex` is removed from the `Graph`.
  Event.VertexPropertyChangedEvent | Represents an action where a `VertexProperty` is modified on a `Vertex`.
  Event.VertexPropertyPropertyChangedEvent | Represents an action where a `Property` is modified on a `VertexProperty`.
  Event.VertexPropertyPropertyRemovedEvent | Represents an action where a `Property` is removed from a `VertexProperty`.
  Event.VertexPropertyRemovedEvent | Represents an action where a `Property` is removed from a `Vertex`.
  Event.VertexRemovedEvent | Represents an action where a `Vertex` is removed from the `Graph`.
  ListCallbackRegistry<E extends Event> |

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