keeping connection alive to websocket when using ServerWebSocketContainer - spring-boot

Question

I was trying to create a websocket based application where the server needs to keep the connection alive with the clients using heartbeat.
I checked the server ServerWebSocketContainer.SockJsServiceOptions class for the same, but could not use it. I am using the code from the spring-integration sample
#Bean
ServerWebSocketContainer serverWebSocketContainer() {
return new ServerWebSocketContainer("/messages").withSockJs();
}
#Bean
MessageHandler webSocketOutboundAdapter() {
return new WebSocketOutboundMessageHandler(serverWebSocketContainer());
}
#Bean(name = "webSocketFlow.input")
MessageChannel requestChannel() {
return new DirectChannel();
}
#Bean
IntegrationFlow webSocketFlow() {
return f -> {
Function<Message , Object> splitter = m -> serverWebSocketContainer()
.getSessions()
.keySet()
.stream()
.map(s -> MessageBuilder.fromMessage(m)
.setHeader(SimpMessageHeaderAccessor.SESSION_ID_HEADER, s)
.build())
.collect(Collectors.toList());
f.split( Message.class, splitter)
.channel(c -> c.executor(Executors.newCachedThreadPool()))
.handle(webSocketOutboundAdapter());
};
}
#RequestMapping("/hi/{name}")
public void send(#PathVariable String name) {
requestChannel().send(MessageBuilder.withPayload(name).build());
}
Please let me know how can I set the heartbeat options ensure the connection is kept alive unless the client de-registers itself.
Thanks

Answer 1

Actually you got it right, but missed a bit of convenience :-).
You can configure it like this:
#Bean
ServerWebSocketContainer serverWebSocketContainer() {
return new ServerWebSocketContainer("/messages")
.withSockJs(new ServerWebSocketContainer.SockJsServiceOptions()
.setHeartbeatTime(60_000));
}
Although it isn't clear for me why you need to configure it at all because of this:
/**
* The amount of time in milliseconds when the server has not sent any
* messages and after which the server should send a heartbeat frame to the
* client in order to keep the connection from breaking.
* <p>The default value is 25,000 (25 seconds).
*/
public SockJsServiceRegistration setHeartbeatTime(long heartbeatTime) {
this.heartbeatTime = heartbeatTime;
return this;
}
UPDATE
In the Spring Integration Samples we have something like stomp-chat application.
I have done there something like this to the stomp-server.xml:
<int-websocket:server-container id="serverWebSocketContainer" path="/chat">
<int-websocket:sockjs heartbeat-time="10000"/>
</int-websocket:server-container>
Added this to the application.properties:
logging.level.org.springframework.web.socket.sockjs.transport.session=trace
And this to the index.html:
sock.onheartbeat = function() {
console.log('heartbeat');
};
After connecting the client I see this in the server log:
2015-10-13 19:03:06.574 TRACE 7960 --- [ SockJS-3] s.w.s.s.t.s.WebSocketServerSockJsSession : Writing SockJsFrame content='h'
2015-10-13 19:03:06.574 TRACE 7960 --- [ SockJS-3] s.w.s.s.t.s.WebSocketServerSockJsSession : Cancelling heartbeat in session sogfe2dn
2015-10-13 19:03:06.574 TRACE 7960 --- [ SockJS-3] s.w.s.s.t.s.WebSocketServerSockJsSession : Scheduled heartbeat in session sogfe2dn
2015-10-13 19:03:16.576 TRACE 7960 --- [ SockJS-8] s.w.s.s.t.s.WebSocketServerSockJsSession : Preparing to write SockJsFrame content='h'
2015-10-13 19:03:16.576 TRACE 7960 --- [ SockJS-8] s.w.s.s.t.s.WebSocketServerSockJsSession : Writing SockJsFrame content='h'
2015-10-13 19:03:16.576 TRACE 7960 --- [ SockJS-8] s.w.s.s.t.s.WebSocketServerSockJsSession : Cancelling heartbeat in session sogfe2dn
2015-10-13 19:03:16.576 TRACE 7960 --- [ SockJS-8] s.w.s.s.t.s.WebSocketServerSockJsSession : Scheduled heartbeat in session sogfe2dn
In the browser's console I see this after:
So, looks like heart-beat feature works well...