As some asynchronous requests can take a long time for processing, the client can decide to close the connection to the server before the response is resumed or before it is written in time to the client. To prevent these use cases, we can use the javax.ws.rs.container.ConnectionCallback interface.

The connection callback will start only if the connection prematurely terminates, or if it is lost while the response returns back to the client. If a response is successfully written, and the client connection is closed as expected, this callback will not even be invoked.