In JMS, which statement describes synchronous communication?

• A. Publish sends a message to a queue and never gets a response back to the message provider
• B. Publish consumes and blocks until a response is returned or timeout
• C. Messages are delivered at least once
• D. It requires a CloudHub service

Answer: (A)

In JMS, synchronous communication means the sender waits for a reply before continuing. The producer sends a message and blocks until a response arrives (or a timeout occurs), enabling a true request‑reply pattern. This behavior is typically implemented by using a reply-to destination (often a temporary queue) and a correlation ID so the consumer can send back the correct response that the producer is waiting for. The statement describing this best is that the publisher consumes and blocks until a response is returned or timeout. The other descriptions don’t fit because one describes fire-and-forget messaging with no reply, another references delivery semantics rather than synchronization, and the last ties to a cloud service rather than JMS behavior.