Module jakarta.websocket.client

Package jakarta.websocket

Interface RemoteEndpoint

All Known Subinterfaces:

RemoteEndpoint.Async, RemoteEndpoint.Basic

public interface RemoteEndpoint

The RemoteEndpoint object is supplied by the container and represents the 'other end' or peer of the Web Socket conversation. Instances of the RemoteEndpoint are obtained from the Session using Session.getBasicRemote() or Session.getAsyncRemote(). Objects of this kind include numerous ways to send web socket messages. There are two kinds of RemoteEndpoint objects: RemoteEndpoint.Basic for synchronous sending of websocket messages, and RemoteEndpoint.Async for sending messages asynchronously.

There is no guarantee of the successful delivery of a web socket message to the peer, but if the action of sending a message causes an error known to the container, the API throws it. RemoteEndpoints include a variety of ways to send messages: by whole message, in parts, and in various data formats including websocket pings and pongs.

Implementations may or may not support batching of messages. More detail of the expected semantics of implementations that do support batching are laid out in setBatchingAllowed(boolean).

Note: Implementations may choose their own schemes for sending large messages in smaller parts. These schemes may or may not bear a relationship to the underlying websocket dataframes in which the message is ultimately sent on the wire.

If the underlying connection is closed and methods on the RemoteEndpoint are attempted to be called, they will result in an error being generated. For the methods that send messages, this will be an IOException, for the methods that alter configuration of the endpoint, this will be runtime IllegalArgumentExceptions.

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static interface	RemoteEndpoint.Async	This representation of the peer of a web socket conversation has the ability to send messages asynchronously.
static interface	RemoteEndpoint.Basic	This representation of the peer of a web socket conversation has the ability to send messages synchronously.

Method Summary

Modifier and Type	Method	Description
void	flushBatch()	This method is only used when batching is allowed for this RemoteEndpint.
boolean	getBatchingAllowed()	Return whether the implementation is allowed to batch outgoing messages before sending.
void	sendPing(ByteBuffer applicationData)	Send a Ping message containing the given application data to the remote endpoint.
void	sendPong(ByteBuffer applicationData)	Allows the developer to send an unsolicited Pong message containing the given application data in order to serve as a unidirectional heartbeat for the session.
void	setBatchingAllowed(boolean allowed)	Indicate to the implementation that it is allowed to batch outgoing messages before sending.

Method Details

setBatchingAllowed

void setBatchingAllowed(boolean allowed)
                 throws IOException

Indicate to the implementation that it is allowed to batch outgoing messages before sending. Not all implementations support batching of outgoing messages. The default mode for RemoteEndpoints is false. If the developer has indicated that batching of outgoing messages is permitted, then the developer must call flushBatch() in order to be sure that all the messages passed into the send methods of this RemoteEndpoint are sent. When batching is allowed, the implementations send operations are considered to have completed if the message has been written to the local batch, in the case when there is still room in the batch for the message, and are considered to have completed if the batch has been send to the peer and the remainder written to the new batch, in the case when writing the message causes the batch to need to be sent. The blocking and asynchronous send methods use this notion of completion in order to complete blocking calls, notify SendHandlers and complete Futures respectively. When batching is allowed, if the developer has called send methods on this RemoteEndpoint without calling flushBatch(), then the implementation may not have sent all the messages the developer has asked to be sent. If the parameter value is false and the implementation has a batch of unsent messages, then the implementation must immediately send the batch of unsent messages.

Parameters:

allowed - whether the implementation is allowed to batch messages.

Throws:

IOException - if batching is being disabled and there are unsent messages this error may be thrown as the implementation sends the batch of unsent messages if there is a problem.

getBatchingAllowed

boolean getBatchingAllowed()

Return whether the implementation is allowed to batch outgoing messages before sending. The default mode for RemoteEndpoints is false. The value may be changed by calling setBatchingAllowed.

Returns:

true if the implementation is allowed to batch outgoing messages before sending, otherwise false

flushBatch

void flushBatch()
         throws IOException

This method is only used when batching is allowed for this RemoteEndpint. Calling this method forces the implementation to send any unsent messages it has been batching.

Throws:

IOException - if the sending of any unsent messages failed

sendPing

void sendPing(ByteBuffer applicationData)
       throws IOException,
IllegalArgumentException

Send a Ping message containing the given application data to the remote endpoint. The corresponding Pong message may be picked up using the MessageHandler.Pong handler.

It is not safe for other threads to use the ByteBuffer until the sending of this message is complete. If the sending of the message completes successfully, the buffer's limit will be unchanged and the buffer's position will be equal to the limit. If the sending of the message does not complete successfully, the state of the buffer is undefined.

Parameters:

applicationData - the data to be carried in the ping request.

Throws:

IOException - if the ping failed to be sent

IllegalArgumentException - if the applicationData exceeds the maximum allowed payload of 125 bytes

sendPong

void sendPong(ByteBuffer applicationData)
       throws IOException,
IllegalArgumentException

Allows the developer to send an unsolicited Pong message containing the given application data in order to serve as a unidirectional heartbeat for the session.

It is not safe for other threads to use the ByteBuffer until the sending of this message is complete. If the sending of the message completes successfully, the buffer's limit will be unchanged and the buffer's position will be equal to the limit. If the sending of the message does not complete successfully, the state of the buffer is undefined.

Parameters:

applicationData - the application data to be carried in the pong response.

Throws:

IOException - if the pong failed to be sent

IllegalArgumentException - if the applicationData exceeds the maximum allowed payload of 125 bytes