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.

Field Summary

Fields

Modifier and Type	Field	Description
static final String	META	Constant representing the meta prefix
static final String	META_CONNECT	Constant representing the connect meta channel
static final String	META_DISCONNECT	Constant representing the disconnect meta channel
static final String	META_HANDSHAKE	Constant representing the handshake meta channel.
static final String	META_SUBSCRIBE	Constant representing the subscribe meta channel
static final String	META_UNSUBSCRIBE	Constant representing the unsubscribe meta channel
static final String	SERVICE	Constant representing the service prefix

Method Summary

Modifier and Type	Method	Description
Object	getAttribute(String name)	Retrieves the value of named channel attribute.
Set<String>	getAttributeNames()
ChannelId	getChannelId()
String	getId()
boolean	isBroadcast()	A broadcasting channel is a channel that is neither a meta channel nor a service channel.
boolean	isDeepWild()	Tells whether a channel contains the deep wild characters '**', for example /foo/**
boolean	isMeta()	Tells whether the channel is a meta channel, that is if its id starts with "/meta/".
boolean	isService()	Tells whether the channel is a service channel, that is if its id starts with "/service/".
boolean	isWild()	Tells whether a channel contains the wild character '*', for example /foo/* or if it is isDeepWild().
Object	removeAttribute(String name)	Removes a named channel attribute.
void	setAttribute(String name, Object value)	Sets a named channel attribute value.

Field Details

META

static final String META

Constant representing the meta prefix

See Also:

• Constant Field Values

SERVICE

static final String SERVICE

Constant representing the service prefix

See Also:

• Constant Field Values

META_HANDSHAKE

static final String META_HANDSHAKE

Constant representing the handshake meta channel.

See Also:

• Constant Field Values

META_CONNECT

static final String META_CONNECT

Constant representing the connect meta channel

See Also:

• Constant Field Values

META_SUBSCRIBE

static final String META_SUBSCRIBE

Constant representing the subscribe meta channel

See Also:

• Constant Field Values

META_UNSUBSCRIBE

static final String META_UNSUBSCRIBE

Constant representing the unsubscribe meta channel

See Also:

• Constant Field Values

META_DISCONNECT

static final String META_DISCONNECT

Constant representing the disconnect meta channel

See Also:

• Constant Field Values

Method Details

getId

String getId()

Returns:

The channel id as a String

getChannelId

ChannelId getChannelId()

Returns:

The channel ID as a ChannelId

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