Package com.vaadin.flow.internal.nodefeature

Class ReturnChannelMap

  • All Implemented Interfaces:
    Serializable
    public class ReturnChannelMap
extends ServerSideFeature
    Server-side node feature that keeps track of the return channels registered for a state node.

    Return channels are only tracked on the server. The client doesn't need to know which channels are registered - it only passes the channel id back to the server. The server checks that the received channel id is (still) valid and logs a warning if it isn't.

    For internal use only. May be renamed or removed in a future release.

    Since:
    2.0
    Author:
    Vaadin Ltd
    See Also:
    Serialized Form

    • Constructor Detail

      • ReturnChannelMap

        public ReturnChannelMap​(StateNode node)
        Creates a new return channel map for the given state node.
        Parameters:
        node - the owning state node, not null

    • Method Detail

      • registerChannel

        public ReturnChannelRegistration registerChannel​(SerializableConsumer<elemental.json.JsonArray> handler)
        Registers a new channel based on a callback that receives the provided arguments when a message is passed to the channel.

        The returned registration can be passed to the client as a parameter to various executeJavaScript methods. The client side representation of the registration will be a function that will send a message to the provided handler.

        Parameters:
        handler - the argument handler, not null
        Returns:
        a return channel registration

      • registerChannel

        public ReturnChannelRegistration registerChannel​(SerializableBiConsumer<elemental.json.JsonArray,​ReturnChannelRegistration> handler)
        Registers a new channel based on a callback that receives the provided arguments and the channel registration when a message is passed to the channel. The purpose of passing the registration to the handler is to allow the channel to unregister itself when it receives a message.

        The returned registration can be passed to the client as a parameter to various executeJavaScript methods. The client side representation of the registration will be a function that will send a message to the provided handler.

        Parameters:
        handler - the argument and registration handler, not null
        Returns:
        a return channel registration

      • get

        public ReturnChannelRegistration get​(int channelId)
        Gets the return channel registration registered with the provided id, or null if no channel is registered with that id.
        Parameters:
        channelId - the channel id to look for
        Returns:
        a return channel registration, or null if no registration exists for the given id

      • hasChannels

        public boolean hasChannels()
        Return if map contains any registered channels.
        Returns:
        true if registered channels exist.