com.neovisionaries.ws.client

Class WebSocket

java.lang.Object

com.neovisionaries.ws.client.WebSocket

public class WebSocket
extends Object

Web socket.

Create WebSocketFactory

WebSocketFactory is a factory class that creates WebSocket instances. The first step is to create a WebSocketFactory instance.

 // Create a WebSocketFactory instance.
 WebSocketFactory factory = new WebSocketFactory();

By default, WebSocketFactory uses SocketFactory.getDefault() for non-secure WebSocket connections (ws:) and SSLSocketFactory.getDefault() for secure WebSocket connections (wss:). You can change this default behavior by using WebSocketFactory.setSocketFactory method, WebSocketFactory.setSSLSocketFactory method and WebSocketFactory.setSSLContext method. Note that you don't have to call a setSSL* method at all if you use the default SSL configuration. Also note that calling setSSLSocketFactory method has no meaning if you have called setSSLContext method. See the description of WebSocketFactory.createSocket(URI) method for details.

The following is an example to set a custom SSL context to a WebSocketFactory instance. (Again, you don't have to call a setSSL* method if you use the default SSL configuration.)

 // Create a custom SSL context.
 SSLContext context = NaiveSSLContext.getInstance("TLS");

 // Set the custom SSL context.
 factory.setSSLContext(context);

NaiveSSLContext used in the above example is a factory class to create an SSLContext which naively accepts all certificates without verification. It's enough for testing purposes. When you see an error message "unable to find valid certificate path to requested target" while testing, try NaiveSSLContext.

HTTP Proxy

If a WebSocket endpoint needs to be accessed via an HTTP proxy, information about the proxy server has to be set to a WebSocketFactory instance before creating a WebSocket instance. Proxy settings are represented by ProxySettings class. A WebSocketFactory instance has an associated ProxySettings instance and it can be obtained by calling WebSocketFactory.getProxySettings() method.

 // Get the associated ProxySettings instance.
 ProxySettings settings = factory.getProxySettings();

ProxySettings class has methods to set information about a proxy server such as setHost method and setPort method. The following is an example to set a secure (https) proxy server.

 // Set a proxy server.
 settings.setServer("https://proxy.example.com");

If credentials are required for authentication at a proxy server, setId method and setPassword method, or setCredentials method can be used to set the credentials. Note that, however, the current implementation supports only Basic Authentication.

 // Set credentials for authentication at a proxy server.
 settings.setCredentials(id, password);
 

Create WebSocket

WebSocket class represents a web socket. Its instances are created by calling one of createSocket methods of a WebSocketFactory instance. Below is the simplest example to create a WebSocket instance.

 // Create a web socket. The scheme part can be one of the following:
 // 'ws', 'wss', 'http' and 'https' (case-insensitive). The user info
 // part, if any, is interpreted as expected. If a raw socket failed
 // to be created, or if HTTP proxy handshake or SSL handshake failed,
 // an IOException is thrown.
 WebSocket ws = new WebSocketFactory()
     .createWebSocket("ws://localhost/endpoint");

There are two ways to set a timeout value for socket connection. The first way is to call setConnectionTimeout(int timeout) method of WebSocketFactory.

 // Create a web socket factory and set 5000 milliseconds as a timeout
 // value for socket connection.
 WebSocketFactory factory = new WebSocketFactory().setConnectionTimeout(5000);

 // Create a web socket. The timeout value set above is used.
 WebSocket ws = factory.createWebSocket("ws://localhost/endpoint");

The other way is to give a timeout value to a createSocket method.

 // Create a web socket factory. The timeout value remains 0.
 WebSocketFactory factory = new WebSocketFactory();

 // Create a web socket with a socket connection timeout value.
 WebSocket ws = factory.createWebSocket("ws://localhost/endpoint", 5000);

The timeout value is passed to connect(SocketAddress, int) method of Socket.

Register Listener

After creating a WebSocket instance, you should call addListener(WebSocketListener) method to register a WebSocketListener that receives web socket events. WebSocketAdapter is an empty implementation of WebSocketListener interface.

 // Register a listener to receive web socket events.
 ws.addListener(new WebSocketAdapter() {
     @Override
     public void onTextMessage(WebSocket websocket, String message) throws Exception {
         // Received a text message.
         ......
     }
 });

Configure WebSocket

Before starting a WebSocket opening handshake with the server, you can configure the web socket instance by using the following methods.

Methods for Configuration

METHOD	DESCRIPTION
addProtocol	Adds an element to Sec-WebSocket-Protocol
addExtension	Adds an element to Sec-WebSocket-Extensions
addHeader	Adds an arbitrary HTTP header.
setUserInfo	Adds Authorization header for Basic Authentication.
getSocket	Gets the underlying Socket instance to configure it.
setExtended	Disables validity checks on RSV1/RSV2/RSV3 and opcode.
setFrameQueueSize	Set the size of the frame queue for congestion control.

Perform Opening Handshake

By calling connect() method, a WebSocket opening handshake is performed synchronously. If an error occurred during the handshake, a WebSocketException would be thrown. Instead, when the handshake succeeds, the connect() implementation creates threads and starts them to read and write web socket frames asynchronously.

 try
 {
     // Perform an opening handshake.
     // This method blocks until the opening handshake is finished.
     ws.connect();
 }
 catch (WebSocketException e)
 {
     // Failed.
 }

Asynchronous Opening Handshake

The simplest way to call connect() method asynchronously is to use connectAsynchronously() method. The implementation of the method creates a thread and calls connect() method in the thread. When the connect() call failed, onConnectError() of WebSocketListener would be called. Note that onConnectError() is called only when connectAsynchronously() was used and the connect() call executed in the background thread failed. Neither direct synchronous connect() nor connect(ExecutorService) (described below) will trigger the callback method.

 // Perform an opening handshake asynchronously.
 ws.connectAsynchronously();
 

Another way to call connect() method asynchronously is to use connect(ExecutorService) method. The method performs a WebSocket opening handshake asynchronously using the given ExecutorService.

 // Prepare an ExecutorService.
 ExecutorService es = Executors.newSingleThreadExecutor();

 // Perform an opening handshake asynchronously.
 Future<WebSocket> future = ws.connect(es);

 try
 {
     // Wait for the opening handshake to complete.
     future.get();
 }
 catch (ExecutionException e)
 {
     if (e.getCause() instanceof WebSocketException)
     {
         ......
     }
 }

The implementation of connect(ExecutorService) method creates a Callable<WebSocket> instance by calling connectable() method and passes the instance to submit(Callable) method of the given ExecutorService. What the implementation of call() method of the Callable instance does is just to call the synchronous connect().

Send Frames

Web socket frames can be sent by sendFrame(WebSocketFrame) method. Other sendXxx methods such as sendText(String) are aliases of sendFrame method. All of the sendXxx methods work asynchronously. However, under some conditions, sendXxx methods may block. See Congestion Control for details.

Below are some examples of sendXxx methods. Note that in normal cases, you don't have to call sendClose() method and sendPong() (or their variants) explicitly because they are called automatically when appropriate.

 // Send a text frame.
 ws.sendText("Hello.");

 // Send a binary frame.
 byte[] binary = ......;
 ws.sendBinary(binary);

 // Send a ping frame.
 ws.sendPing("Are you there?");

If you want to send fragmented frames, you have to know the details of the specification (5.4. Fragmentation). Below is an example to send a text message ("How are you?") which consists of 3 fragmented frames.

 // The first frame must be either a text frame or a binary frame.
 // And its FIN bit must be cleared.
 WebSocketFrame firstFrame = WebSocketFrame
     .createTextFrame("How ")
     .setFin(false);

 // Subsequent frames must be continuation frames. The FIN bit of
 // all continuation frames except the last one must be cleared.
 // Note that the FIN bit of frames returned from
 // WebSocketFrame.createContinuationFrame methods is cleared, so
 // the example below does not clear the FIN bit explicitly.
 WebSocketFrame secondFrame = WebSocketFrame
     .createContinuationFrame("are ");

 // The last frame must be a continuation frame with the FIN bit set.
 // Note that the FIN bit of frames returned from
 // WebSocketFrame.createContinuationFrame methods is cleared, so
 // the FIN bit of the last frame must be set explicitly.
 WebSocketFrame lastFrame = WebSocketFrame
     .createContinuationFrame("you?")
     .setFin(true);

 // Send a text message which consists of 3 frames.
 ws.sendFrame(firstFrame)
   .sendFrame(secondFrame)
   .sendFrame(lastFrame);

Alternatively, the same as above can be done like this.

 // Send a text message which consists of 3 frames.
 ws.sendText("How ", false)
   .sendContinuation("are ")
   .sendContinuation("you?", true);

Send Ping/Pong Frames Periodically

You can send ping frames periodically by calling setPingInterval method with an interval in milliseconds between ping frames. This method can be called both before and after connect() method. Passing zero stops the periodical sending.

 // Send a ping per 60 seconds.
 ws.setPingInterval(60 * 1000);

 // Stop the periodical sending.
 ws.setPingInterval(0);

Likewise, you can send pong frames periodically by calling setPongInterval method. "A Pong frame MAY be sent unsolicited." (RFC 6455, 5.5.3. Pong)

Auto Flush

By default, a frame is automatically flushed to the server immediately after sendFrame method is executed. This automatic flush can be disabled by calling setAutoFlush(false).

 // Disable auto-flush.
 ws.setAutoFlush(false);

To flush frames manually, call flush() method. Note that this method works asynchronously.

 // Flush frames to the server manually.
 ws.flush();

Congestion Control

sendXxx methods queue a WebSocketFrame instance to the internal queue. By default, no upper limit is imposed on the queue size, so sendXxx methods do not block. However, this behavior may cause a problem if your WebSocket client application sends too many WebSocket frames in a short time for the WebSocket server to process. In such a case, you may want sendXxx methods to block when many frames are queued.

You can set an upper limit on the internal queue by calling setFrameQueueSize(int) method. As a result, if the number of frames in the queue has reached the upper limit when a sendXxx method is called, the method blocks until the queue gets spaces. The code snippet below is an example to set 5 as the upper limit of the internal frame queue.

 // Set 5 as the frame queue size.
 ws.setFrameQueueSize(5);

Note that under some conditions, even if the queue is full, sendXxx methods do not block. For example, in the case where the thread to send frames (WritingThread) is going to stop or has already stopped. In addition, method calls to send a control frame (e.g. sendClose() and sendPing()) do not block.

Disconnect WebSocket

Before a web socket is closed, a closing handshake is performed. A closing handshake is started (1) when the server sends a close frame to the client or (2) when the client sends a close frame to the server. You can start a closing handshake by calling disconnect() method (or by sending a close frame manually).

 // Close the web socket connection.
 ws.disconnect();

disconnect() method has some variants. If you want to change the close code and the reason phrase of the close frame that this client will send to the server, use a variant method such as disconnect(int, String). disconnect() method itself is an alias of disconnect(WebSocketCloseCode.NORMAL, null).

Reconnection

connect() method can be called at most only once regardless of whether the method succeeded or failed. If you want to re-connect to the WebSocket endpoint, you have to create a new WebSocket instance again by calling one of createSocket methods of a WebSocketFactory. You may find recreate() method useful if you want to create a new WebSocket instance that has the same settings as the original instance. Note that, however, settings you made on the raw socket of the original WebSocket instance are not copied.

 // Create a new WebSocket instance and connect to the same endpoint.
 ws = ws.recreate().connect();

There is a variant of recreate() method that takes a timeout value for socket connection. If you want to use a timeout value that is different from the one used when the existing WebSocket instance was created, use recreate(int timeout) method.

Note that you should not trigger reconnection in onError() method because onError() may be called multiple times due to one error. Instead, onDisconnected() is the right place to trigger reconnection.

Error Handling

WebSocketListener has some onXxxError() methods such as onFrameError() and onSendError(). Among such methods, onError() is a special one. It is always called before any other onXxxError() is called. For example, in the implementation of run() method of ReadingThread, Throwable is caught and onError() and onUnexpectedError() are called in this order. The following is the implementation.

 @Override
 public void run()
 {
     try
     {
         main();
     }
     catch (Throwable t)
     {
         // An uncaught throwable was detected in the reading thread.
         WebSocketException cause = new WebSocketException(
             WebSocketError.UNEXPECTED_ERROR_IN_READING_THREAD,
             "An uncaught throwable was detected in the reading thread", t);

         // Notify the listeners.
         ListenerManager manager = mWebSocket.getListenerManager();
         manager.callOnError(cause);
         manager.callOnUnexpectedError(cause);
     }
 }

So, you can handle all error cases in onError() method. However, note that onError() may be called multiple times due to one error, so don't try to trigger reconnection in onError(). Instead, onDiconnected() is the right place to trigger reconnection.

All onXxxError() methods receive a WebSocketException instance as the second argument (the first argument is a WebSocket instance). The exception class provides getError() method which returns a WebSocketError enum entry. Entries in WebSocketError enum are possible causes of errors that may occur in the implementation of this library. The error causes are so granular that they can make it easy for you to find the root cause when an error occurs.

Throwables thrown by implementations of onXXX() callback methods are passed to handleCallbackError() of WebSocketListener.

 @Override
 public void handleCallbackError(WebSocket websocket, Throwable cause) throws Exception {
     // Throwables thrown by onXxx() callback methods come here.
 }

Author:

Takahiko Kawasaki

See Also:

RFC 6455 (The WebSocket Protocol), [GitHub] nv-websocket-client

Method Summary

Modifier and Type	Method and Description
WebSocket	addExtension(String extension) Add a value for Sec-WebSocket-Extension.
WebSocket	addExtension(WebSocketExtension extension) Add a value for Sec-WebSocket-Extension.
WebSocket	addHeader(String name, String value) Add a pair of extra HTTP header.
WebSocket	addListener(WebSocketListener listener) Add a listener to receive events on this web socket.
WebSocket	addListeners(List<WebSocketListener> listeners) Add listeners.
WebSocket	addProtocol(String protocol) Add a value for Sec-WebSocket-Protocol.
WebSocket	clearExtensions() Remove all extensions from Sec-WebSocket-Extension.
WebSocket	clearHeaders() Clear all extra HTTP headers.
WebSocket	clearListeners() Remove all the listeners from this web socket.
WebSocket	clearProtocols() Remove all protocols from Sec-WebSocket-Protocol.
WebSocket	clearUserInfo() Clear the credentials to connect to the web socket endpoint.
WebSocket	connect() Send an opening handshake to the server, receive the response and then start threads to communicate with the server.
Future<WebSocket>	connect(ExecutorService executorService) Execute connect() asynchronously using the given ExecutorService.
Callable<WebSocket>	connectable() Get a new Callable<WebSocket> instance whose call() method calls connect() method of this WebSocket instance.
WebSocket	connectAsynchronously() Execute connect() asynchronously by creating a new thread and calling connect() in the thread.
WebSocket	disconnect() Disconnect the web socket.
WebSocket	disconnect(int closeCode) Disconnect the web socket.
WebSocket	disconnect(int closeCode, String reason) Disconnect the web socket.
WebSocket	disconnect(String reason) Disconnect the web socket.
protected void	finalize()
WebSocket	flush() Flush frames to the server.
List<WebSocketExtension>	getAgreedExtensions() Get the agreed extensions.
String	getAgreedProtocol() Get the agreed protocol.
int	getFrameQueueSize() Get the size of the frame queue.
long	getPingInterval() Get the interval of periodical ping frames.
long	getPongInterval() Get the interval of periodical pong frames.
Socket	getSocket() Get the raw socket which this web socket uses internally.
WebSocketState	getState() Get the current state of this web socket.
URI	getURI() Get the URI of the web socket endpoint.
boolean	isAutoFlush() Check if flush is performed automatically after sendFrame(WebSocketFrame) is done.
boolean	isExtended() Check if extended use of web socket frames are allowed.
boolean	isOpen() Check if the current state of this web socket is OPEN.
WebSocket	recreate() Create a new WebSocket instance that has the same settings as this instance.
WebSocket	recreate(int timeout) Create a new WebSocket instance that has the same settings as this instance.
WebSocket	removeExtension(WebSocketExtension extension) Remove an extension from Sec-WebSocket-Extension.
WebSocket	removeExtensions(String name) Remove extensions from Sec-WebSocket-Extension by an extension name.
WebSocket	removeHeaders(String name) Remove pairs of extra HTTP headers.
WebSocket	removeListener(WebSocketListener listener) Remove a listener from this web socket.
WebSocket	removeListeners(List<WebSocketListener> listeners) Remove listeners.
WebSocket	removeProtocol(String protocol) Remove a protocol from Sec-WebSocket-Protocol.
WebSocket	sendBinary(byte[] message) Send a binary message to the server.
WebSocket	sendBinary(byte[] payload, boolean fin) Send a binary frame to the server.
WebSocket	sendClose() Send a close frame to the server.
WebSocket	sendClose(int closeCode) Send a close frame to the server.
WebSocket	sendClose(int closeCode, String reason) Send a close frame to the server.
WebSocket	sendContinuation() Send a continuation frame to the server.
WebSocket	sendContinuation(boolean fin) Send a continuation frame to the server.
WebSocket	sendContinuation(byte[] payload) Send a continuation frame to the server.
WebSocket	sendContinuation(byte[] payload, boolean fin) Send a continuation frame to the server.
WebSocket	sendContinuation(String payload) Send a continuation frame to the server.
WebSocket	sendContinuation(String payload, boolean fin) Send a continuation frame to the server.
WebSocket	sendFrame(WebSocketFrame frame) Send a web socket frame to the server.
WebSocket	sendPing() Send a ping frame to the server.
WebSocket	sendPing(byte[] payload) Send a ping frame to the server.
WebSocket	sendPing(String payload) Send a ping frame to the server.
WebSocket	sendPong() Send a pong frame to the server.
WebSocket	sendPong(byte[] payload) Send a pong frame to the server.
WebSocket	sendPong(String payload) Send a pong frame to the server.
WebSocket	sendText(String message) Send a text message to the server.
WebSocket	sendText(String payload, boolean fin) Send a text frame to the server.
WebSocket	setAutoFlush(boolean auto) Enable or disable auto-flush of sent frames.
WebSocket	setExtended(boolean extended) Allow or disallow extended use of web socket frames.
WebSocket	setFrameQueueSize(int size) Set the size of the frame queue.
WebSocket	setPingInterval(long interval) Set the interval of periodical ping frames.
WebSocket	setPongInterval(long interval) Set the interval of periodical pong frames.
WebSocket	setUserInfo(String userInfo) Set the credentials to connect to the web socket endpoint.
WebSocket	setUserInfo(String id, String password) Set the credentials to connect to the web socket endpoint.

Methods inherited from class java.lang.Object

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

Method Detail

recreate

public WebSocket recreate()
                   throws IOException

Create a new WebSocket instance that has the same settings as this instance. Note that, however, settings you made on the raw socket are not copied.

The WebSocketFactory instance that you used to create this WebSocket instance is used again.

This method calls recreate(int) with the timeout value that was used when this instance was created. If you want to create a socket connection with a different timeout value, use recreate(int) method instead.

Returns:

A new WebSocket instance.

Throws:

IOException - WebSocketFactory.createSocket(URI) threw an exception.

Since:

1.6

recreate

public WebSocket recreate(int timeout)
                   throws IOException

Create a new WebSocket instance that has the same settings as this instance. Note that, however, settings you made on the raw socket are not copied.

The WebSocketFactory instance that you used to create this WebSocket instance is used again.

Parameters:

timeout - The timeout value in milliseconds for socket timeout. A timeout of zero is interpreted as an infinite timeout.

Returns:

A new WebSocket instance.

Throws:

IllegalArgumentException - The given timeout value is negative.

IOException - WebSocketFactory.createSocket(URI) threw an exception.

Since:

1.10

finalize

protected void finalize()
                 throws Throwable

Overrides:

finalize in class Object

Throws:

Throwable

getState

public WebSocketState getState()

Get the current state of this web socket.

The initial state is CREATED. When connect() is called, the state is changed to CONNECTING, and then to OPEN after a successful opening handshake. The state is changed to CLOSING when a closing handshake is started, and then to CLOSED when the closing handshake finished.

See the description of WebSocketState for details.

Returns:

The current state.

See Also:

WebSocketState

isOpen

public boolean isOpen()

Check if the current state of this web socket is OPEN.

Returns:

true if the current state is OPEN.

Since:

1.1

addProtocol

public WebSocket addProtocol(String protocol)

Add a value for Sec-WebSocket-Protocol.

Parameters:

protocol - A protocol name.

Returns:

this object.

Throws:

IllegalArgumentException - The protocol name is invalid. A protocol name must be a non-empty string with characters in the range U+0021 to U+007E not including separator characters.

removeProtocol

public WebSocket removeProtocol(String protocol)

Remove a protocol from Sec-WebSocket-Protocol.

Parameters:

protocol - A protocol name. null is silently ignored.

Returns:

this object.

Since:

1.14

clearProtocols

public WebSocket clearProtocols()

Remove all protocols from Sec-WebSocket-Protocol.

Returns:

this object.

Since:

1.14

addExtension

public WebSocket addExtension(WebSocketExtension extension)

Add a value for Sec-WebSocket-Extension.

Parameters:

extension - An extension. null is silently ignored.

Returns:

this object.

addExtension

public WebSocket addExtension(String extension)

Add a value for Sec-WebSocket-Extension. The input string should comply with the format described in 9.1. Negotiating Extensions in RFC 6455.

Parameters:

extension - A string that represents a WebSocket extension. If it does not comply with RFC 6455, no value is added to Sec-WebSocket-Extension.

Returns:

this object.

Since:

1.14

removeExtension

public WebSocket removeExtension(WebSocketExtension extension)

Remove an extension from Sec-WebSocket-Extension.

Parameters:

extension - An extension to remove. null is silently ignored.

Returns:

this object.

Since:

1.14

removeExtensions

public WebSocket removeExtensions(String name)

Remove extensions from Sec-WebSocket-Extension by an extension name.

Parameters:

name - An extension name. null is silently ignored.

Returns:

this object.

Since:

1.14

clearExtensions

public WebSocket clearExtensions()

Remove all extensions from Sec-WebSocket-Extension.

Returns:

this object.

Since:

1.14

addHeader

public WebSocket addHeader(String name,
                           String value)

Add a pair of extra HTTP header.

Parameters:

name - An HTTP header name. When null or an empty string is given, no header is added.

value - The value of the HTTP header.

Returns:

this object.

removeHeaders

public WebSocket removeHeaders(String name)

Remove pairs of extra HTTP headers.

Parameters:

name - An HTTP header name. null is silently ignored.

Returns:

this object.

Since:

1.14

clearHeaders

public WebSocket clearHeaders()

Clear all extra HTTP headers.

Returns:

this object.

Since:

1.14

setUserInfo

public WebSocket setUserInfo(String userInfo)

Set the credentials to connect to the web socket endpoint.

Parameters:

userInfo - The credentials for Basic Authentication. The format should be id:password.

Returns:

this object.

setUserInfo

public WebSocket setUserInfo(String id,
                             String password)

Set the credentials to connect to the web socket endpoint.

Parameters:

id - The ID.

password - The password.

Returns:

this object.

clearUserInfo

public WebSocket clearUserInfo()

Clear the credentials to connect to the web socket endpoint.

Returns:

this object.

Since:

1.14

isExtended

public boolean isExtended()

Check if extended use of web socket frames are allowed.

When extended use is allowed, values of RSV1/RSV2/RSV3 bits and opcode of frames are not checked. On the other hand, if not allowed (default), non-zero values for RSV1/RSV2/RSV3 bits and unknown opcodes cause an error. In such a case, onFrameError method of listeners are called and the web socket is eventually closed.

Returns:

true if extended use of web socket frames are allowed.

setExtended

public WebSocket setExtended(boolean extended)

Allow or disallow extended use of web socket frames.

Parameters:

extended - true to allow extended use of web socket frames.

Returns:

this object.

isAutoFlush

public boolean isAutoFlush()

Check if flush is performed automatically after sendFrame(WebSocketFrame) is done. The default value is true.

Returns:

true if flush is performed automatically.

Since:

1.5

setAutoFlush

public WebSocket setAutoFlush(boolean auto)

Enable or disable auto-flush of sent frames.

Parameters:

auto - true to enable auto-flush. false to disable it.

Returns:

this object.

Since:

1.5

flush

public WebSocket flush()

Flush frames to the server. Flush is performed asynchronously.

Returns:

this object.

Since:

1.5

getFrameQueueSize

public int getFrameQueueSize()

Get the size of the frame queue. The default value is 0 and it means there is no limit on the queue size.

Returns:

The size of the frame queue.

Since:

1.15

setFrameQueueSize

public WebSocket setFrameQueueSize(int size)
                            throws IllegalArgumentException

Set the size of the frame queue. The default value is 0 and it means there is no limit on the queue size.

sendXxx methods queue a WebSocketFrame instance to the internal queue. If the number of frames in the queue has reached the upper limit (which has been set by this method) when a sendXxx method is called, the method blocks until the queue gets spaces.

Under some conditions, even if the queue is full, sendXxx methods do not block. For example, in the case where the thread to send frames (WritingThread) is going to stop or has already stopped. In addition, method calls to send a control frame (e.g. sendClose() and sendPing()) do not block.

Parameters:

size - The queue size. 0 means no limit. Negative numbers are not allowed.

Returns:

this object.

Throws:

IllegalArgumentException - size is negative.

Since:

1.15

getPingInterval

public long getPingInterval()

Get the interval of periodical ping frames.

Returns:

The interval in milliseconds.

Since:

1.2

setPingInterval

public WebSocket setPingInterval(long interval)

Set the interval of periodical ping frames.

Setting a positive number starts sending ping frames periodically. Setting zero stops the periodical sending. This method can be called both before and after connect() method.

Parameters:

interval - The interval in milliseconds. A negative value is regarded as zero.

Returns:

this object.

Since:

1.2

getPongInterval

public long getPongInterval()

Get the interval of periodical pong frames.

Returns:

The interval in milliseconds.

Since:

1.2

setPongInterval

public WebSocket setPongInterval(long interval)

Set the interval of periodical pong frames.

Setting a positive number starts sending pong frames periodically. Setting zero stops the periodical sending. This method can be called both before and after connect() method.

An excerpt from RFC 6455, 5.5.3. Pong

A Pong frame MAY be sent unsolicited. This serves as a unidirectional heartbeat. A response to an unsolicited Pong frame is not expected.

Parameters:

interval - The interval in milliseconds. A negative value is regarded as zero.

Returns:

this object.

Since:

1.2

addListener

public WebSocket addListener(WebSocketListener listener)

Add a listener to receive events on this web socket.

Parameters:

listener - A listener to add.

Returns:

this object.

addListeners

public WebSocket addListeners(List<WebSocketListener> listeners)

Add listeners.

Parameters:

listeners - Listeners to add. null is silently ignored. null elements in the list are ignored, too.

Returns:

this object.

Since:

1.14

removeListener

public WebSocket removeListener(WebSocketListener listener)

Remove a listener from this web socket.

Parameters:

listener - A listener to remove. null won't cause an error.

Returns:

this object.

Since:

1.13

removeListeners

public WebSocket removeListeners(List<WebSocketListener> listeners)

Remove listeners.

Parameters:

listeners - Listeners to remove. null is silently ignored. null elements in the list are ignored, too.

Returns:

this object.

Since:

1.14

clearListeners

public WebSocket clearListeners()

Remove all the listeners from this web socket.

Returns:

this object.

Since:

1.13

getSocket

public Socket getSocket()

Get the raw socket which this web socket uses internally.

Returns:

The underlying Socket instance.

getURI

public URI getURI()

Get the URI of the web socket endpoint. The scheme part is either "ws" or "wss". The authority part is always empty.

Returns:

The URI of the web socket endpoint.

Since:

1.1

connect

public WebSocket connect()
                  throws WebSocketException

Send an opening handshake to the server, receive the response and then start threads to communicate with the server.

As necessary, addProtocol(String), addExtension(WebSocketExtension) addHeader(String, String) should be called before you call this method. It is because the parameters set by these methods are used in the opening handshake.

Also, as necessary, getSocket() should be used to set up socket parameters before you call this method. For example, you can set the socket timeout like the following.

 WebSocket websocket = ......;
 websocket.getSocket().setSoTimeout(5000);
 

If the web socket endpoint requires Basic Authentication, you can set credentials by setUserInfo(userInfo) or setUserInfo(id, password) before you call this method. Note that if the URI passed to WebSocketFactory.createSocket method contains the user-info part, you don't have to call setUserInfo method.

Note that this method can be called at most only once regardless of whether this method succeeded or failed. If you want to re-connect to the WebSocket endpoint, you have to create a new WebSocket instance again by calling one of createSocket methods of a WebSocketFactory. You may find recreate() method useful if you want to create a new WebSocket instance that has the same settings as this instance. (But settings you made on the raw socket are not copied.)

Returns:

this object.

Throws:

WebSocketException -

• The current state of the web socket is not CREATED
• Connecting the server failed.
• The opening handshake failed.

connect

public Future<WebSocket> connect(ExecutorService executorService)

Execute connect() asynchronously using the given ExecutorService. This method is just an alias of the following.

executorService.submit(connectable())

Parameters:

executorService - An ExecutorService to execute a task created by connectable().

Returns:

The value returned from ExecutorService.submit(Callable).

Throws:

NullPointerException - If the given ExecutorService is null.

RejectedExecutionException - If the given ExecutorService rejected the task created by connectable().

Since:

1.7

See Also:

connectAsynchronously()

connectable

public Callable<WebSocket> connectable()

Get a new Callable<WebSocket> instance whose call() method calls connect() method of this WebSocket instance.

Returns:

A new Callable<WebSocket> instance for asynchronous connect().

Since:

1.7

See Also:

connect(ExecutorService)

connectAsynchronously

public WebSocket connectAsynchronously()

Execute connect() asynchronously by creating a new thread and calling connect() in the thread. If connect() failed, onConnectError() method of WebSocketListener is called.

Returns:

this object.

Since:

1.8

disconnect

public WebSocket disconnect()

Disconnect the web socket.

This method is an alias of disconnect(WebSocketCloseCode.NORMAL, null).

Returns:

this object.

disconnect

public WebSocket disconnect(int closeCode)

Disconnect the web socket.

This method is an alias of disconnect(closeCode, null).

Parameters:

closeCode - The close code embedded in a close frame which this WebSocket client will send to the server.

Returns:

this object.

Since:

1.5

disconnect

public WebSocket disconnect(String reason)

Disconnect the web socket.

This method is an alias of disconnect(WebSocketCloseCode.NORMAL, reason).

Parameters:

reason - The reason embedded in a close frame which this WebSocket client will send to the server. Note that the length of the bytes which represents the given reason must not exceed 125. In other words, (reason.getBytes("UTF-8").length <= 125) must be true.

Returns:

this object.

Since:

1.5

disconnect

public WebSocket disconnect(int closeCode,
                            String reason)

Disconnect the web socket.

Parameters:

closeCode - The close code embedded in a close frame which this WebSocket client will send to the server.

reason - The reason embedded in a close frame which this WebSocket client will send to the server. Note that the length of the bytes which represents the given reason must not exceed 125. In other words, (reason.getBytes("UTF-8").length <= 125) must be true.

Returns:

this object.

Since:

1.5

See Also:

WebSocketCloseCode, RFC 6455, 5.5.1. Close

getAgreedExtensions

public List<WebSocketExtension> getAgreedExtensions()

Get the agreed extensions.

This method works correctly only after connect() succeeds (= after the opening handshake succeeds).

Returns:

The agreed extensions.

getAgreedProtocol

public String getAgreedProtocol()

Get the agreed protocol.

This method works correctly only after connect() succeeds (= after the opening handshake succeeds).

Returns:

The agreed protocol.

sendFrame

public WebSocket sendFrame(WebSocketFrame frame)

Send a web socket frame to the server.

This method just queues the given frame. Actual transmission is performed asynchronously.

When the current state of this web socket is not OPEN, this method does not accept the frame.

Sending a close frame changes the state to CLOSING (if the current state is neither CLOSING nor CLOSED).

Note that the validity of the give frame is not checked. For example, even if the payload length of a given frame is greater than 125 and the opcode indicates that the frame is a control frame, this method accepts the given frame.

Parameters:

frame - A web socket frame to be sent to the server. If null is given, nothing is done.

Returns:

this object.

sendContinuation

public WebSocket sendContinuation()

Send a continuation frame to the server.

This method is an alias of sendFrame(WebSocketFrame.createContinuationFrame()).

Note that the FIN bit of a frame sent by this method is false. If you want to set the FIN bit, use sendContinuation(boolean fin) with fin=true.

Returns:

this object.

sendContinuation

public WebSocket sendContinuation(boolean fin)

Send a continuation frame to the server.

This method is an alias of sendFrame(WebSocketFrame.createContinuationFrame().setFin(fin)).

Parameters:

fin - The FIN bit value.

Returns:

this object.

sendContinuation

public WebSocket sendContinuation(String payload)

Send a continuation frame to the server.

This method is an alias of sendFrame(WebSocketFrame.createContinuationFrame(payload)).

Note that the FIN bit of a frame sent by this method is false. If you want to set the FIN bit, use sendContinuation(String payload, boolean fin) with fin=true.

Parameters:

payload - The payload of a continuation frame.

Returns:

this object.

sendContinuation

public WebSocket sendContinuation(String payload,
                                  boolean fin)

Send a continuation frame to the server.

This method is an alias of sendFrame(WebSocketFrame.createContinuationFrame(payload).setFin(fin)).

Parameters:

payload - The payload of a continuation frame.

fin - The FIN bit value.

Returns:

this object.

sendContinuation

public WebSocket sendContinuation(byte[] payload)

Send a continuation frame to the server.

This method is an alias of sendFrame(WebSocketFrame.createContinuationFrame(payload)).

Note that the FIN bit of a frame sent by this method is false. If you want to set the FIN bit, use sendContinuation(byte[] payload, boolean fin) with fin=true.

Parameters:

payload - The payload of a continuation frame.

Returns:

this object.

sendContinuation

public WebSocket sendContinuation(byte[] payload,
                                  boolean fin)

Send a continuation frame to the server.

This method is an alias of sendFrame(WebSocketFrame.createContinuationFrame(payload).setFin(fin)).

Parameters:

payload - The payload of a continuation frame.

fin - The FIN bit value.

Returns:

this object.

sendText

public WebSocket sendText(String message)

Send a text message to the server.

This method is an alias of sendFrame(WebSocketFrame.createTextFrame(message)).

If you want to send a text frame that is to be followed by continuation frames, use setText(String payload, boolean fin) with fin=false.

Parameters:

message - A text message to be sent to the server.

Returns:

this object.

sendText

public WebSocket sendText(String payload,
                          boolean fin)

Send a text frame to the server.

This method is an alias of sendFrame(WebSocketFrame.createTextFrame(payload).setFin(fin)).

Parameters:

payload - The payload of a text frame.

fin - The FIN bit value.

Returns:

this object.

sendBinary

public WebSocket sendBinary(byte[] message)

Send a binary message to the server.

This method is an alias of sendFrame(WebSocketFrame.createBinaryFrame(message)).

If you want to send a binary frame that is to be followed by continuation frames, use setBinary(byte[] payload, boolean fin) with fin=false.

Parameters:

message - A binary message to be sent to the server.

Returns:

this object.

sendBinary

public WebSocket sendBinary(byte[] payload,
                            boolean fin)

Send a binary frame to the server.

This method is an alias of sendFrame(WebSocketFrame.createBinaryFrame(payload).setFin(fin)).

Parameters:

payload - The payload of a binary frame.

fin - The FIN bit value.

Returns:

this object.

sendClose

public WebSocket sendClose()

Send a close frame to the server.

This method is an alias of sendFrame(WebSocketFrame.createCloseFrame()).

Returns:

this object.

sendClose

public WebSocket sendClose(int closeCode)

Send a close frame to the server.

This method is an alias of sendFrame(WebSocketFrame.createCloseFrame(closeCode)).

Parameters:

closeCode - The close code.

Returns:

this object.

See Also:

WebSocketCloseCode

sendClose

public WebSocket sendClose(int closeCode,
                           String reason)

Send a close frame to the server.

This method is an alias of sendFrame(WebSocketFrame.createCloseFrame(closeCode, reason)).

Parameters:

closeCode - The close code.

reason - The close reason. Note that a control frame's payload length must be 125 bytes or less (RFC 6455, 5.5. Control Frames).

Returns:

this object.

See Also:

WebSocketCloseCode

sendPing

public WebSocket sendPing()

Send a ping frame to the server.

This method is an alias of sendFrame(WebSocketFrame.createPingFrame()).

Returns:

this object.

sendPing

public WebSocket sendPing(byte[] payload)

Send a ping frame to the server.

This method is an alias of sendFrame(WebSocketFrame.createPingFrame(payload)).

Parameters:

payload - The payload for a ping frame. Note that a control frame's payload length must be 125 bytes or less (RFC 6455, 5.5. Control Frames).

Returns:

this object.

sendPing

public WebSocket sendPing(String payload)

Send a ping frame to the server.

This method is an alias of sendFrame(WebSocketFrame.createPingFrame(payload)).

Parameters:

payload - The payload for a ping frame. Note that a control frame's payload length must be 125 bytes or less (RFC 6455, 5.5. Control Frames).

Returns:

this object.

sendPong

public WebSocket sendPong()

Send a pong frame to the server.

This method is an alias of sendFrame(WebSocketFrame.createPongFrame()).

Returns:

this object.

sendPong

public WebSocket sendPong(byte[] payload)

Send a pong frame to the server.

This method is an alias of sendFrame(WebSocketFrame.createPongFrame(payload)).

Parameters:

payload - The payload for a pong frame. Note that a control frame's payload length must be 125 bytes or less (RFC 6455, 5.5. Control Frames).

Returns:

this object.

sendPong

public WebSocket sendPong(String payload)

Send a pong frame to the server.

This method is an alias of sendFrame(WebSocketFrame.createPongFrame(payload)).

Parameters:

payload - The payload for a pong frame. Note that a control frame's payload length must be 125 bytes or less (RFC 6455, 5.5. Control Frames).

Returns:

this object.