You need to exchange large binary messages using chunks in a WebSocket application. Identify two ways in which you can receive partial messages. (Choose two.)

Question

Options

• ADefine an @OnMessage method with a single MimePart parameter.
• BUse a ChunkListener interface implementation.
• CUse a MessageHandler.Partial<ByteBuffer> interface implementation.
• DDefine an @OnMessage method with byte [] as the first parameter and a boolean as the second

Explanation

C and D are the correct answers.

In the Java WebSocket API (JSR 356), partial binary messages can be received in exactly two ways. First, MessageHandler.Partial<ByteBuffer> (C) is an interface you register on a Session object; its onMessage(ByteBuffer data, boolean last) method is invoked for each arriving chunk, with last signaling the final piece. Second, an @OnMessage method (D) supports partial delivery when its signature is void onMessage(byte[] data, boolean last) - the same boolean flag indicates whether the current chunk is the final one.

Why the distractors are wrong:

• A is wrong because MimePart belongs to MIME/multipart HTTP processing (JAX-RS), not the WebSocket API - there is no such parameter type in @OnMessage for chunked binary handling.
• B is wrong because ChunkListener does not exist in the Java WebSocket API; it is a fabricated distractor with no corresponding interface in JSR 356.

Memory tip: Think "Partial = Parameter boolean OR Partial interface." Any legitimate partial-message mechanism in the WebSocket API involves a boolean last flag - either as a method parameter in @OnMessage or inside MessageHandler.Partial<T>. If an answer choice lacks that boolean concept, it's a distractor.

No community discussion yet for this question.