Package org.cometd.bayeux

Interface Channel

  • All Known Subinterfaces:
    ClientSessionChannel, ConfigurableServerChannel, ServerChannel
    All Known Implementing Classes:
    AbstractClientSession.AbstractSessionChannel, BayeuxClient.BayeuxClientChannel, LocalSessionImpl.LocalChannel, ServerChannelImpl
    public interface Channel

    A Bayeux channel is the primary message routing mechanism within Bayeux: both Bayeux clients and Bayeux server use channels to group listeners that are interested in receiving messages with that channel.

    This interface is the common root for both the client side representation of a channel and the server side representation of a channel.

    Channels are identified with strings that look like paths (e.g. "/foo/bar") called "channel id". Meta channels have channel ids starting with "/meta/" and are reserved for the operation of they Bayeux protocol. Service channels have channel ids starting with "/service/" and are channels for which publish is disabled, so that only server side listeners will receive the messages.

    A channel id may also be specified with wildcards. For example "/meta/*" refers to all top level meta channels like "/meta/subscribe" or "/meta/handshake". The channel "/foo/**" is deeply wild and refers to all channels like "/foo/bar", "/foo/bar/bob" and "/foo/bar/wibble/bip". Wildcards can only be specified as last segment of a channel; therefore channel "/foo/*/bar/** is an invalid channel.

    • Method Detail

      • getId

        String getId()
        Returns:
        The channel id as a String

      • isMeta

        boolean isMeta()

        Tells whether the channel is a meta channel, that is if its id starts with "/meta/".

        Returns:
        true if the channel is a meta channel

      • isService

        boolean isService()

        Tells whether the channel is a service channel, that is if its id starts with "/service/".

        Returns:
        true if the channel is a service channel

      • isBroadcast

        boolean isBroadcast()

        A broadcasting channel is a channel that is neither a meta channel nor a service channel.

        Returns:
        whether the channel is a broadcasting channel

      • isWild

        boolean isWild()

        Tells whether a channel contains the wild character '*', for example /foo/* or if it is isDeepWild().

        Returns:
        true if the channel contains the '*' or '**' characters

      • isDeepWild

        boolean isDeepWild()

        Tells whether a channel contains the deep wild characters '**', for example /foo/**

        Returns:
        true if the channel contains the '**' characters

      • setAttribute

        void setAttribute​(String name,
                  Object value)

        Sets a named channel attribute value.

        Channel attributes are convenience data that allows arbitrary application data to be associated with a channel.

        Parameters:
        name - the attribute name
        value - the attribute value

      • getAttribute

        Object getAttribute​(String name)

        Retrieves the value of named channel attribute.

        Parameters:
        name - the name of the attribute
        Returns:
        the attribute value or null if the attribute is not present

      • getAttributeNames

        Set<String> getAttributeNames()
        Returns:
        the list of channel attribute names.

      • removeAttribute

        Object removeAttribute​(String name)

        Removes a named channel attribute.

        Parameters:
        name - the name of the attribute
        Returns:
        the value of the attribute