# fiftyone.core.session.client Session server-sent events client. Copyright 2017-2026, Voxel51, Inc.
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**Classes:** | [`Client`](#fiftyone.core.session.client.Client)(address, auto, port, remote, start_time) | | |---------------------------------------------------------------------------------------------|----| ### *class* fiftyone.core.session.client.Client(address: str, auto: [bool](fiftyone.core.stages.md#fiftyone.core.stages.Exists.bool), port: int, remote: [bool](fiftyone.core.stages.md#fiftyone.core.stages.Exists.bool), start_time: float) Bases: `object` **Attributes:** | [`address`](#fiftyone.core.session.client.Client.address) | | |-----------------------------------------------------------------|---------------------------------| | [`auto`](#fiftyone.core.session.client.Client.auto) | | | [`port`](#fiftyone.core.session.client.Client.port) | | | [`remote`](#fiftyone.core.session.client.Client.remote) | | | [`start_time`](#fiftyone.core.session.client.Client.start_time) | | | [`origin`](#fiftyone.core.session.client.Client.origin) | The origin of the server | | [`is_open`](#fiftyone.core.session.client.Client.is_open) | Whether the client is connected | **Methods:** | [`open`](#fiftyone.core.session.client.Client.open)(state) | Open the client connection | |-------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------| | [`close`](#fiftyone.core.session.client.Client.close)() | Close the client connection | | [`send_event`](#fiftyone.core.session.client.Client.send_event)(event) | Sends an event to the server | | [`add_event_listener`](#fiftyone.core.session.client.Client.add_event_listener)(event_name, listener) | Adds an event listener callback for the provided event name. | | [`remove_event_listener`](#fiftyone.core.session.client.Client.remove_event_listener)(event_name, listener) | Removes an event listener callback for the provided event name if it has been registered | #### address *: str* #### auto *: [bool](fiftyone.core.stages.md#fiftyone.core.stages.Exists.bool)* #### port *: int* #### remote *: [bool](fiftyone.core.stages.md#fiftyone.core.stages.Exists.bool)* #### start_time *: float* #### *property* origin *: str* The origin of the server #### *property* is_open *: str* Whether the client is connected #### open(state: [StateDescription](fiftyone.core.state.md#fiftyone.core.state.StateDescription)) → None Open the client connection Arg: : state: the initial state description #### close() Close the client connection #### send_event(event: [CaptureNotebookCell](fiftyone.core.session.events.md#fiftyone.core.session.events.CaptureNotebookCell) | [CloseSession](fiftyone.core.session.events.md#fiftyone.core.session.events.CloseSession) | [DeactivateNotebookCell](fiftyone.core.session.events.md#fiftyone.core.session.events.DeactivateNotebookCell) | [ReactivateNotebookCell](fiftyone.core.session.events.md#fiftyone.core.session.events.ReactivateNotebookCell) | [SelectSamples](fiftyone.core.session.events.md#fiftyone.core.session.events.SelectSamples) | [SelectLabels](fiftyone.core.session.events.md#fiftyone.core.session.events.SelectLabels) | [SetColorScheme](fiftyone.core.session.events.md#fiftyone.core.session.events.SetColorScheme) | [SetGroupSlice](fiftyone.core.session.events.md#fiftyone.core.session.events.SetGroupSlice) | [SetSample](fiftyone.core.session.events.md#fiftyone.core.session.events.SetSample) | [SetLabelSelectionStyle](fiftyone.core.session.events.md#fiftyone.core.session.events.SetLabelSelectionStyle) | [SetSampleSelectionStyle](fiftyone.core.session.events.md#fiftyone.core.session.events.SetSampleSelectionStyle) | [SetSpaces](fiftyone.core.session.events.md#fiftyone.core.session.events.SetSpaces) | [StateUpdate](fiftyone.core.session.events.md#fiftyone.core.session.events.StateUpdate) | [SetFieldVisibilityStage](fiftyone.core.session.events.md#fiftyone.core.session.events.SetFieldVisibilityStage)) → None Sends an event to the server * **Parameters:** **event** – the event #### add_event_listener(event_name: str, listener: Callable) → None Adds an event listener callback for the provided event name. Events sent from client and from the server connection will be dispatched to the listener * **Parameters:** * **event_name** – the event name * **listener** – the listener callback #### remove_event_listener(event_name: str, listener: Callable) → None Removes an event listener callback for the provided event name if it has been registered * **Parameters:** * **event_name** – the event name * **listener** – the listener callback