org.cometd.client

Class BayeuxClient

java.lang.Object

org.cometd.common.AbstractClientSession

org.cometd.client.BayeuxClient

All Implemented Interfaces:

Bayeux, ClientSession, Session

public class BayeuxClient
extends AbstractClientSession
implements Bayeux

BayeuxClient is the implementation of a client for the Bayeux protocol.

A BayeuxClient can receive/publish messages from/to a Bayeux server, and it is the counterpart in Java of the JavaScript library used in browsers (and as such it is ideal for Swing applications, load testing tools, etc.).

A BayeuxClient handshakes with a Bayeux server and then subscribes ClientSessionChannel.MessageListener to channels in order to receive messages, and may also publish messages to the Bayeux server.

BayeuxClient relies on pluggable transports for communication with the Bayeux server, and the most common transport is LongPollingTransport, which uses HTTP to transport Bayeux messages and it is based on Jetty's HTTP client.

When the communication with the server is finished, the BayeuxClient can be disconnected from the Bayeux server.

Typical usage:

 // Handshake
 String url = "http://localhost:8080/cometd";
 BayeuxClient client = new BayeuxClient(url, LongPollingTransport.create(null));
 client.handshake();
 client.waitFor(1000, BayeuxClient.State.CONNECTED);

 // Subscription to channels
 ClientSessionChannel channel = client.getChannel("/foo");
 channel.subscribe(new ClientSessionChannel.MessageListener()
 {
     public void onMessage(ClientSessionChannel channel, Message message)
     {
         // Handle the message
     }
 });

 // Publishing to channels
 Map<String, Object> data = new HashMap<String, Object>();
 data.put("bar", "baz");
 channel.publish(data);

 // Disconnecting
 client.disconnect();
 client.waitFor(1000, BayeuxClient.State.DISCONNECTED);
 

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected class	BayeuxClient.BayeuxClientChannel
static class	BayeuxClient.State The states that a BayeuxClient may assume

Nested classes/interfaces inherited from class org.cometd.common.AbstractClientSession

AbstractClientSession.AbstractSessionChannel

Nested classes/interfaces inherited from interface org.cometd.bayeux.Bayeux

Bayeux.BayeuxListener

Nested classes/interfaces inherited from interface org.cometd.bayeux.client.ClientSession

ClientSession.Extension

Field Summary

Fields

Modifier and Type	Field and Description
static String	BACKOFF_INCREMENT_OPTION
static String	BAYEUX_VERSION
static String	MAX_BACKOFF_OPTION

Fields inherited from class org.cometd.common.AbstractClientSession

CALLBACK_KEY, SUBSCRIBER_KEY

Constructor Summary

Constructors

Constructor and Description
BayeuxClient(String url, ClientTransport transport, ClientTransport... transports) Creates a BayeuxClient that will connect to the Bayeux server at the given URL and with the given transport(s).
BayeuxClient(String url, ScheduledExecutorService scheduler, ClientTransport transport, ClientTransport... transports) Creates a BayeuxClient that will connect to the Bayeux server at the given URL, with the given scheduler and with the given transport(s).

Method Summary

Methods

Modifier and Type	Method and Description
void	abort() Interrupts abruptly the communication with the Bayeux server.
protected void	debug(String message, Object... args)
void	disconnect()
void	disconnect(ClientSessionChannel.MessageListener callback)
boolean	disconnect(long timeout) Performs a disconnect and uses the given timeout to wait for the disconnect to complete.
String	dump()
protected void	enqueueSend(Message.Mutable message)
protected void	failMessage(Message message, Throwable x)
protected void	failMessages(Throwable x, Message... messages)
List<String>	getAllowedTransports()
long	getBackoffIncrement()
String	getCookie(String name) Retrieves the cookie with the given name, if available.
String	getId()
Set<String>	getKnownTransportNames()
long	getMaxBackoff()
Object	getOption(String qualifiedName)
Set<String>	getOptionNames()
Map<String,Object>	getOptions()
protected BayeuxClient.State	getState()
ClientTransport	getTransport()
ClientTransport	getTransport(String transport)
void	handshake()
void	handshake(ClientSessionChannel.MessageListener callback)
BayeuxClient.State	handshake(long waitMs) Performs the handshake and waits at most the given time for the handshake to complete.
void	handshake(Map<String,Object> handshakeFields)
void	handshake(Map<String,Object> template, ClientSessionChannel.MessageListener callback)
BayeuxClient.State	handshake(Map<String,Object> template, long waitMs) Performs the handshake with the given template and waits at most the given time for the handshake to complete.
protected void	initialize()
boolean	isConnected()
boolean	isDebugEnabled()
boolean	isDisconnected()
boolean	isHandshook()
protected AbstractClientSession.AbstractSessionChannel	newChannel(ChannelId channelId)
protected ChannelId	newChannelId(String channelId)
protected Message.Mutable	newMessage()
protected void	notifyListeners(Message.Mutable message)
void	onFailure(Throwable x, Message[] messages) Callback method invoked when the given messages have failed to be sent.
void	onMessages(List<Message.Mutable> messages) Callback method invoke when the given messages have just arrived from the Bayeux server.
void	onSending(Message[] messages) Callback method invoked when the given messages have hit the network towards the Bayeux server.
protected void	onTransportFailure(String oldTransportName, String newTransportName, Throwable failure)
protected void	processConnect(Message.Mutable connect)
protected void	processDisconnect(Message.Mutable disconnect)
protected void	processHandshake(Message.Mutable handshake)
protected void	processMessage(Message.Mutable message)
protected boolean	scheduleConnect(long interval, long backoff)
protected boolean	scheduleHandshake(long interval, long backoff)
protected void	sendBatch()
protected boolean	sendConnect()
protected boolean	sendHandshake()
protected boolean	sendMessages(Message.Mutable... messages)
void	setCookie(String name, String value) Sets a cookie that never expires.
void	setCookie(String name, String value, int maxAge) Sets a cookie with the given max age in seconds.
void	setDebugEnabled(boolean debug)
void	setOption(String qualifiedName, Object value)
protected void	terminate()
boolean	waitFor(long waitMs, BayeuxClient.State state, BayeuxClient.State... states) Waits for this BayeuxClient to reach the given state(s) within the given time.

Methods inherited from class org.cometd.common.AbstractClientSession

addExtension, batch, dump, endBatch, extendRcv, extendSend, getAttribute, getAttributeNames, getChannel, getChannels, getExtensions, isBatching, newMessageId, notifyListener, receive, registerCallback, registerSubscriber, removeAttribute, removeExtension, resetSubscriptions, setAttribute, startBatch, unregisterCallback, unregisterSubscriber

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

BACKOFF_INCREMENT_OPTION

public static final String BACKOFF_INCREMENT_OPTION

See Also:

Constant Field Values

MAX_BACKOFF_OPTION

public static final String MAX_BACKOFF_OPTION

See Also:

Constant Field Values

BAYEUX_VERSION

public static final String BAYEUX_VERSION

See Also:

Constant Field Values

Constructor Detail

BayeuxClient

public BayeuxClient(String url,
            ClientTransport transport,
            ClientTransport... transports)

Creates a BayeuxClient that will connect to the Bayeux server at the given URL and with the given transport(s).

This constructor allocates a new scheduler; it is recommended that when creating a large number of BayeuxClients a shared scheduler is used.

Parameters:

url - the Bayeux server URL to connect to

transport - the default (mandatory) transport to use

transports - additional optional transports to use in case the default transport cannot be used

See Also:

BayeuxClient(String, ScheduledExecutorService, ClientTransport, ClientTransport...)

BayeuxClient

public BayeuxClient(String url,
            ScheduledExecutorService scheduler,
            ClientTransport transport,
            ClientTransport... transports)

Creates a BayeuxClient that will connect to the Bayeux server at the given URL, with the given scheduler and with the given transport(s).

Parameters:

url - the Bayeux server URL to connect to

scheduler - the scheduler to use for scheduling timed operations

transport - the default (mandatory) transport to use

transports - additional optional transports to use in case the default transport cannot be used

Method Detail

getBackoffIncrement

public long getBackoffIncrement()

Returns:

the period of time that increments the pause to wait before trying to reconnect after each failed attempt to connect to the Bayeux server

See Also:

getMaxBackoff()

getMaxBackoff

public long getMaxBackoff()

Returns:

the maximum pause to wait before trying to reconnect after each failed attempt to connect to the Bayeux server

See Also:

getBackoffIncrement()

getCookie

public String getCookie(String name)

Retrieves the cookie with the given name, if available.

Note that currently only HTTP transports support cookies.

Parameters:

name - the cookie name

Returns:

the cookie value

See Also:

setCookie(String, String)

setCookie

public void setCookie(String name,
             String value)

Sets a cookie that never expires.

Parameters:

name - the cookie name

value - the cookie value

See Also:

setCookie(String, String, int)

setCookie

public void setCookie(String name,
             String value,
             int maxAge)

Sets a cookie with the given max age in seconds.

Parameters:

name - the cookie name

value - the cookie value

maxAge - the max age of the cookie, in seconds, before expiration

getId

public String getId()

Specified by:

getId in interface Session

isHandshook

public boolean isHandshook()

Specified by:

isHandshook in interface Session

isConnected

public boolean isConnected()

Specified by:

isConnected in interface Session

isDisconnected

public boolean isDisconnected()

Returns:

whether this BayeuxClient is disconnecting or disconnected

getState

protected BayeuxClient.State getState()

Returns:

the current state of this BayeuxClient

handshake

public void handshake()

Specified by:

handshake in interface ClientSession

handshake

public void handshake(Map<String,Object> handshakeFields)

Specified by:

handshake in interface ClientSession

handshake

public void handshake(ClientSessionChannel.MessageListener callback)

handshake

public void handshake(Map<String,Object> template,
             ClientSessionChannel.MessageListener callback)

Specified by:

handshake in interface ClientSession

handshake

public BayeuxClient.State handshake(long waitMs)

Performs the handshake and waits at most the given time for the handshake to complete.

When this method returns, the handshake may have failed (for example because the Bayeux server denied it), so it is important to check the return value to know whether the handshake completed or not.

Parameters:

waitMs - the time to wait for the handshake to complete

Returns:

the state of this BayeuxClient

See Also:

handshake(Map, long)

handshake

public BayeuxClient.State handshake(Map<String,Object> template,
                           long waitMs)

Performs the handshake with the given template and waits at most the given time for the handshake to complete.

When this method returns, the handshake may have failed (for example because the Bayeux server denied it), so it is important to check the return value to know whether the handshake completed or not.

Parameters:

template - the template object to be merged with the handshake message

waitMs - the time to wait for the handshake to complete

Returns:

the state of this BayeuxClient

See Also:

handshake(long)

sendHandshake

protected boolean sendHandshake()

waitFor

public boolean waitFor(long waitMs,
              BayeuxClient.State state,
              BayeuxClient.State... states)

Waits for this BayeuxClient to reach the given state(s) within the given time.

Parameters:

waitMs - the time to wait to reach the given state(s)

state - the state to reach

states - additional states to reach in alternative

Returns:

true if one of the state(s) has been reached within the given time, false otherwise

sendConnect

protected boolean sendConnect()

newChannelId

protected ChannelId newChannelId(String channelId)

Specified by:

newChannelId in class AbstractClientSession

newChannel

protected AbstractClientSession.AbstractSessionChannel newChannel(ChannelId channelId)

Specified by:

newChannel in class AbstractClientSession

sendBatch

protected void sendBatch()

Specified by:

sendBatch in class AbstractClientSession

sendMessages

protected boolean sendMessages(Message.Mutable... messages)

disconnect

public void disconnect()

Specified by:

disconnect in interface Session

See Also:

disconnect(long)

disconnect

public void disconnect(ClientSessionChannel.MessageListener callback)

Specified by:

disconnect in interface ClientSession

disconnect

public boolean disconnect(long timeout)

Performs a disconnect and uses the given timeout to wait for the disconnect to complete.

When a disconnect is sent to the server, the server also wakes up the long poll that may be outstanding, so that a connect reply message may arrive to the client later than the disconnect reply message.

This method waits for the given timeout for the disconnect reply, but also waits the same timeout for the last connect reply; in the worst case the maximum time waited will therefore be twice the given timeout parameter.

This method returns true if the disconnect reply message arrived within the given timeout parameter, no matter if the connect reply message arrived or not.

Parameters:

timeout - the timeout to wait for the disconnect to complete

Returns:

true if the disconnect completed within the given timeout

abort

public void abort()

Interrupts abruptly the communication with the Bayeux server.

This method may be useful to simulate network failures.

See Also:

disconnect()

processHandshake

protected void processHandshake(Message.Mutable handshake)

processConnect

protected void processConnect(Message.Mutable connect)

processDisconnect

protected void processDisconnect(Message.Mutable disconnect)

processMessage

protected void processMessage(Message.Mutable message)

scheduleHandshake

protected boolean scheduleHandshake(long interval,
                        long backoff)

scheduleConnect

protected boolean scheduleConnect(long interval,
                      long backoff)

getAllowedTransports

public List<String> getAllowedTransports()

Specified by:

getAllowedTransports in interface Bayeux

getKnownTransportNames

public Set<String> getKnownTransportNames()

Specified by:

getKnownTransportNames in interface Bayeux

getTransport

public ClientTransport getTransport(String transport)

Specified by:

getTransport in interface Bayeux

getTransport

public ClientTransport getTransport()

setDebugEnabled

public void setDebugEnabled(boolean debug)

Parameters:

debug - whether the debug level for logging should be enabled

See Also:

isDebugEnabled()

isDebugEnabled

public boolean isDebugEnabled()

Returns:

whether the debug level for logging is enabled

See Also:

setDebugEnabled(boolean)

debug

protected void debug(String message,
         Object... args)

initialize

protected void initialize()

terminate

protected void terminate()

getOption

public Object getOption(String qualifiedName)

Specified by:

getOption in interface Bayeux

setOption

public void setOption(String qualifiedName,
             Object value)

Specified by:

setOption in interface Bayeux

getOptionNames

public Set<String> getOptionNames()

Specified by:

getOptionNames in interface Bayeux

getOptions

public Map<String,Object> getOptions()

Returns:

the options that configure with BayeuxClient

newMessage

protected Message.Mutable newMessage()

enqueueSend

protected void enqueueSend(Message.Mutable message)

failMessages

protected void failMessages(Throwable x,
                Message... messages)

failMessage

protected void failMessage(Message message,
               Throwable x)

notifyListeners

protected void notifyListeners(Message.Mutable message)

Overrides:

notifyListeners in class AbstractClientSession

onSending

public void onSending(Message[] messages)

Callback method invoked when the given messages have hit the network towards the Bayeux server.

The messages may not be modified, and any modification will be useless because the message have already been sent.

Parameters:

messages - the messages sent

onMessages

public void onMessages(List<Message.Mutable> messages)

Callback method invoke when the given messages have just arrived from the Bayeux server.

The messages may be modified, but it's suggested to use Extensions instead.

Extensions will be processed after the invocation of this method.

Parameters:

messages - the messages arrived

onFailure

public void onFailure(Throwable x,
             Message[] messages)

Callback method invoked when the given messages have failed to be sent.

The default implementation logs the failure at DEBUG level.

Parameters:

x - the exception that caused the failure

messages - the messages being sent

dump

public String dump()

onTransportFailure

protected void onTransportFailure(String oldTransportName,
                      String newTransportName,
                      Throwable failure)