Using the f:websocket Tag
Java Platform, Enterprise Edition (Java EE) 8
The Java EE Tutorial

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Using the f:websocket Tag

Table 17-1 describes the attributes of the f:websocket tag.

Table 17-1 Attributes of the f:websocket Tag

Name

Type

Description

channel

String

Required. The name of the WebSocket channel. It may not be an EL expression and may only contain alphanumeric characters, hyphens, underscores, and periods. All open WebSockets on the same channel name will receive the same push notification from the server.

id

String

Optional. The identifier of the UIWebSocket component to be created.

scope

String

Optional. The scope of the WebSocket channel. It may not be an EL expression. Allowed values (case insensitive) are: application, session, and view.

When the value is application, all channels with the same name throughout the application receive the same push message. When the value is session, only the channels with the same name in the current user session receive the same push message. When the value is view, only the channel in the current view receives the push message.

The default scope is application. When the user attribute is specified, then the default scope is session.

user

Serializable

Optional. The user identifier of the WebSocket channel, so that user-targeted push messages can be sent. It must implement Serializable and preferably have a low memory footprint.

Hint: Use #{request.remoteUser} or #{someLoggedInUser.id}.

All open WebSockets on the same channel and user will receive the same push message from the server.

onopen

String

Optional. The JavaScript event handler function that is invoked when the WebSocket is opened. The function is invoked with one argument: the channel name.

onmessage

String

Optional. The JavaScript event handler function that is invoked when a push message is received from the server. The function is invoked with three arguments: the push message, the channel name, and the MessageEvent instance.

onclose

String

Optional. The JavaScript event handler function that is invoked when the WebSocket is closed. The function is invoked with three arguments: the close reason code, the channel name, and the CloseEvent.

Note that this will also be invoked on errors. If an error occurred, you can inspect the close reason code and which code was given (for example, when the code is not 1000).

connected

Boolean

Optional. Specifies whether to auto-reconnect the WebSocket. Defaults to true. It is interpreted as a JavaScript instruction to open or close the WebSocket push connection.

This attribute is implicitly re-evaluated on every ajax request by a PreRenderViewEvent listener on the UIViewRoot. You can also explicitly set it to false and then manually control it in JavaScript using jsf.push.open(clientId) and jsf.push.close(clientId).

rendered

Boolean

Optional. Specifies whether to render the WebSocket scripts. Defaults to true.

This attribute is implicitly re-evaluated on every ajax request by a PreRenderViewEvent listener on the UIViewRoot. If the value changes to false while the WebSocket is already opened, then the WebSocket will implicitly be closed.

binding

UIComponent

Optional. The value binding expression to a backing bean property bound to the component instance for the UIComponent created by this tag.


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