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package javax.websocket;


/**
 * Developers implement MessageHandlers in order to receive incoming messages
 * during a web socket conversation.
 * Each web socket session uses no more than one thread at a time to call its MessageHandlers. This means
 * that, provided each message handler instance is used to handle messages for one web socket session, at most
 * one thread at a time can be calling any of its methods. Developers who wish to handle messages from multiple
 * clients within the same message handlers may do so by adding the same instance as a handler on each of the Session
 * objects for the clients. In that case, they will need to code with the possibility of their MessageHandler
 * being called concurrently by multiple threads, each one arising from a different client session.
 *
 * 

See {@link Endpoint} for a usage example. * * @author dannycoward */ public interface MessageHandler { /** * This kind of handler is notified by the container on arrival of a complete message. If the message is received in parts, * the container buffers it until it is has been fully received before this method is called. * *

For handling incoming text messages, the allowed types for T are *

    *
  • {@link java.lang.String}
  • *
  • {@link java.io.Reader}
  • *
  • any developer object for which there is a corresponding {@link Decoder.Text} or * {@link Decoder.TextStream} configured
  • *
* *

For handling incoming binary messages, the allowed types for T are *

    *
  • {@link java.nio.ByteBuffer}
  • *
  • byte[]
  • *
  • {@link java.io.InputStream}
  • *
  • any developer object for which there is a corresponding {@link Decoder.Binary} or * {@link Decoder.BinaryStream} configured *
* *

For handling incoming pong messages, the type of T is {@link PongMessage} * *

Developers should not continue to reference message objects of type {@link java.io.Reader}, {@link java.nio.ByteBuffer} * or {@link java.io.InputStream} after the completion of the onMessage() call, since they * may be recycled by the implementation. * * @param The type of the message object that this MessageHandler will consume. */ interface Whole extends MessageHandler { /** * Called when the message has been fully received. * * @param message the message data. */ void onMessage(T message); } /** * This kind of handler is notified by the implementation as it becomes ready * to deliver parts of a whole message. * *

For handling parts of text messages, the type T is {@link java.lang.String} * *

For handling parts of binary messages, the allowable types for T are *

    *
  • {@link java.nio.ByteBuffer}
  • *
  • byte[]
  • *
* *

Developers should not continue to reference message objects of type {@link java.nio.ByteBuffer} * after the completion of the onMessage() call, since they * may be recycled by the implementation. * *

Note: Implementations may choose their own schemes for delivering large messages in smaller parts through this API. These * schemes may or may not bear a relationship to the underlying websocket dataframes in which the message * is received off the wire. * * @param The type of the object that represent pieces of the incoming message that this MessageHandler will consume. */ interface Partial extends MessageHandler { /** * Called when the next part of a message has been fully received. * * @param partialMessage the partial message data. * @param last flag to indicate if this partialMessage is the last of the whole message being delivered. */ void onMessage(T partialMessage, boolean last); } }





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