I'm working with websocket to push notification using rabbitmq like a message broker. In controller i using SimpMessageTemplate to convertAndSendToUser a message via the nick name of user
#PostMapping("/{nickName}/notification")
public void send(#PathVariable String nickName,
#RequestBody NotificationRes notificationRes) {
messagingTemplate.convertAndSendToUser(nickName, "/exchange/amq.direct/notification", notificationRes);
}
I make some configuration by using JWT to authorize user and set user to StompHeaderAccessor when user start connecting.
Spring security messaging currently convert send to user. With that endpoint spring will convert it to /exchange/amq.direct/notification-user{session_id}. And rabbitmq will create an auto deleted queue. So, if I have 100 connect in the same time. It will create 100 queue. I want to custom this flow to create one queue and spring will using message header for spring can know the user to send message to.
I did some research about UserDestinationResolver but I still don't know how to make spring can handle with header instead of url like ...-user{session_id}. #.#. What should i do for this situatioin?
we want to integrate third party library(Eclipse XText LSP) into our SpringBoot webapp.
This library works "interactively" with the user (like chat). XText API requires input and output stream to work. We want to use WebSocket to let users interact with this library smoothly (send/retrieve json messages).
We have a problem with SpringBoot because SpringBoot support for WebSocket doesn't expose input/output streams. We wrote custom TextWebSocketHandler (subclass) but none of it's methods provide access to in/out streams.
We also tried with HandshakeInterceptor (to obtain in/out streams after handshake ) but with no success.
Can we use SpringBoot WebSocket API in this scenario or should we use some lower level (Servlet?) API ?
Regards Daniel
I am not sure if this will fit your architecture or not, but I have achieved this by using Spring Boot's STOMP support and wiring it into a custom org.eclipse.lsp4j.jsonrpc.RemoteEndpoint, rather than using a lower level API.
The approach was inspired by reading through the code provided in org.eclipse.lsp4j.launch.LSPLauncher.
JSON handler
Marhalling and unmarshalling the JSON needs to be done with the API provided with the xtext language server, rather than Jackson (which would be used by the Spring STOMP integration)
Map<String, JsonRpcMethod> supportedMethods = new LinkedHashMap<String, JsonRpcMethod>();
supportedMethods.putAll(ServiceEndpoints.getSupportedMethods(LanguageClient.class));
supportedMethods.putAll(languageServer.supportedMethods());
jsonHandler = new MessageJsonHandler(supportedMethods);
jsonHandler.setMethodProvider(remoteEndpoint);
Response / notifications
Responses and notifications are sent by a message consumer which is passed to the remoteEndpoint when constructed. The message must be marshalled by the jsonHandler so as to prevent Jackson doing it.
remoteEndpoint = new RemoteEndpoint(new MessageConsumer() {
#Override
public void consume(Message message) {
simpMessagingTemplate.convertAndSendToUser('user', '/lang/message',
jsonHandler.serialize(message));
}
}, ServiceEndpoints.toEndpoint(languageServer));
Requests
Requests can be received by using a #MessageMapping method that takes the whole #Payload as a String to avoid Jackson unmarshalling it. You can then unmarshall yourself and pass the message to the remoteEndpoint.
#MessageMapping("/lang/message")
public void incoming(#Payload String message) {
remoteEndpoint.consume(jsonHandler.parseMessage(message));
}
There may be a better way to do this, and I'll watch this question with interest, but this is an approach that I have found to work.
I have a Spring Boot app (Jhipster) that uses STOMP over WebSockets to communicate information from the server to users.
I recently added an ActiveMQ server to handle scaling the app horizontally, with an Amazon auto-scaling group / load-balancer.
I make use the convertAndSendToUser() method, which works on single instances of the app to locate the authenticated users' "individual queue" so only they receive the message.
However, when I launch the app behind the load balancer, I am finding that messages are only being sent to the user if the event is generated on the server that their websocket-proxy connection (to the broker) is established on?
How do I ensure the message goes through ActiveMQ to whichever instance of the app that the user is actually "connected too" regardless of which instance receives, say an HTTP Request that executes the convertAndSendToUser() event?
For reference here is my StompBrokerRelayMessageHandler:
#Bean
public AbstractBrokerMessageHandler stompBrokerRelayMessageHandler() {
StompBrokerRelayMessageHandler handler = (StompBrokerRelayMessageHandler) super.stompBrokerRelayMessageHandler();
handler.setTcpClient(new Reactor2TcpClient<>(
new StompTcpFactory(orgProperties.getAws().getAmazonMq().getStompRelayHost(),
orgProperties.getAws().getAmazonMq().getStompRelayPort(), orgProperties.getAws().getAmazonMq
().getSsl())
));
return handler;
}
#Override
public void configureMessageBroker(MessageBrokerRegistry config) {
config.enableStompBrokerRelay("/queue", "/topic")
.setSystemLogin(orgProperties.getAws().getAmazonMq().getStompRelayHostUser())
.setSystemPasscode(orgProperties.getAws().getAmazonMq().getStompRelayHostPass())
.setClientLogin(orgProperties.getAws().getAmazonMq().getStompRelayHostUser())
.setClientPasscode(orgProperties.getAws().getAmazonMq().getStompRelayHostPass());
config.setApplicationDestinationPrefixes("/app");
}
I have found the name corresponding to the queue that is generated on ActiveMQ by examining the headers in the SessionSubscribeEvent, that is generated in the listener when a user subscribes to a user-queue, as simpSessionId.
#Override
#EventListener({SessionSubscribeEvent.class})
public void onSessionSubscribeEvent(SessionSubscribeEvent event) {
log.debug("Session Subscribe Event:" +
"{}", event.getMessage().getHeaders().toString());
}
Corresponding queues' can be found in ActiveMQ, in the format: {simpDestination}-user{simpSessionId}
Could I save the sessionId in a key-value pair and just push messages onto that topic channel?
I also found some possibilities of setting ActiveMQ specific STOMP properties in the CONNECT/SUBSCRIBE frame to create durable subscribers if I set these properties will Spring than understand the routing?
client-id & subcriptionName
Modifying the MessageBrokerReigstry config resolved the issue:
config.enableStompBrokerRelay("/queue", "/topic")
.setUserDestinationBroadcast("/topic/registry.broadcast")
Based on this paragraph in the documentation section 4.4.13:
In a multi-application server scenario a user destination may remain
unresolved because the user is connected to a different server. In
such cases you can configure a destination to broadcast unresolved
messages to so that other servers have a chance to try. This can be
done through the userDestinationBroadcast property of the
MessageBrokerRegistry in Java config and the
user-destination-broadcast attribute of the message-broker element in
XML
I did not see any documentation on "why" /topic/registry.broadcast was the correct "topic" destination, but I am finding various iterations of it:
websocket sessions sample doesn't cluster.. spring-session-1.2.2
What is MultiServerUserRegistry in spring websocket?
Spring websocket - sendToUser from a cluster does not work from backup server
In Spring Integration, I am using a couple of channel adapters for sending/receiving messages from a server socket. I always create client connections with the following adapters:
#Bean
public TcpReceivingChannelAdapter tcpIn(AbstractClientConnectionFactory connectionFactory) throws Exception {
TcpReceivingChannelAdapter receiver = new TcpReceivingChannelAdapter();
receiver.setOutputChannel(fromTcp ());
receiver.setConnectionFactory(connectionFactory);
return receiver;
}
#Bean
#ServiceActivator(inputChannel = "toTcp")
public TcpSendingMessageHandler tcpOut(AbstractClientConnectionFactory connectionFactory) throws Exception {
TcpSendingMessageHandler sender = new TcpSendingMessageHandler();
sender.setConnectionFactory(connectionFactory);
sender.setClientMode(true);
return sender;
}
The problem here is the server is answering in the same socket to the remote port (my opened socket port) . For example, If I connect a socket to 127.0.0.1:4444 the server is answering to my opened port (dynamic with Socket tcp) 6873 instead 4444.It is using the same socket.
A quick answer could be to use a TcpOutboundGateway but I have a couple of problems with this scenario:
I need to manage the connection events without taking into account
send /read operations. For instance, I have to auto-connect and open
the Socket before sending any message.
According to the documentation:
for high-volume messages, consider using a collaborating pair of
channel adapters. However, you will need to provide collaboration
logic.
Which component should I use for request/response sockets in a high-volume scenario?
Just read the Reference Manual from the words:
To achieve high-volume throughput (avoiding the pitfalls of using gateways as mentioned above) you may consider configuring a pair of collaborating outbound and inbound channel adapters.
Also take a look into TCP Multiplex Sample:
This sample demonstrates how to configure collaborating channel adapters, on both the client and server sides, and one technique for correlating the responses to the corresponding request.
In our current application, we use Spring Websockets over STOMP. We are looking to scale horizontally. Are there any best practices on how we should handle websocket traffic over multiple tomcat instances and how can we maintain session info across multiple nodes.Is there a working sample that one can refer to?
Horizontally scaling WebSockets is actually very different than horizontally scaling stateless/stateful HTTP only based applications.
Horizontally Scaling Stateless HTTP app: just spin up some application instances in different machines and put a load balancer in front of them. There are quite a lot different load balancer solutions such as HAProxy, Nginx, etc. If you are on a cloud environment such as AWS you could also have managed solutions such as Elastic Load Balancer.
Horizontally Scaling Stateful HTTP app: it would be great if we could have all applications being stateless everytime, but unfortunately that's not always possible. So, when dealing with stateful HTTP apps, you must care about the HTTP session, which is a basically a local storage for each different client where the web server can store data that is kept across different HTTP requests (such as when dealing with a Shopping Cart). Well, in this case, when scaling horizontally you should be aware that, as I said, it's a LOCAL storage, so ServerA will not be able to handle an HTTP session that is on ServerB. In other words, if for any reason Client1 that is being served by ServerA starts suddenly to be served by ServerB, his HTTP session will be lost (and his shopping cart will be gone!). The reasons could be a node failure or even a deployment.
In order to address this issue, you can't keep HTTP sessions only locally, that is, you must store them on another external component. That are several components that would be able to handle this, such as any relational database, but that would be actually an overhead. Some NoSQL databases can handle this key-value behavior very well, such as Redis.
Now, with the HTTP session being stored on Redis, if a client starts to be served by another server, it will fetch the client's HTTP session from Redis and load it into its memory, so everything will continue working and the user will not lost his HTTP session anymore.
You can use Spring Session to easily store the HTTP session on Redis.
Horizontally Scaling WebSocket app: When a WebSocket connection is established, the server must keep the connection opened with the client so that they can exchange data in both directions. When a client is listening to a destination such as "/topic/public.messages" we say the client is subscribed to this destination. In Spring, when you use the simpleBroker approach, the subscriptions are kept in memory, so what happens for instance if Client1 is being served by ServerA and wants to send a message using WebSocket to Client2 being served by ServerB? You already know the answer! The message will not be delivered to Client2 because Server1 not even know about the Client2's subscription.
So, in order to address this issue, again you have to externalize the WebSockets subscriptions. As you are using STOMP as a subprotocol, you need an external component that can act as a external STOMP broker. There are quite a lot tools able to do this, but I would suggest RabbitMQ.
Now, you must change your Spring configuration so that it will not keep the subscriptions in-memory. Instead, it will delegate the subscriptions to a external STOMP broker. You can easily achieve this with some basic configurations such as enableStompBrokerRelay.
The important thing to note is that HTTP session is different than WebSocket session. Using Spring Session to store the HTTP session in Redis has absolutely nothing to do with horizontally scaling WebSockets.
I've coded a complete Web Chat Application with Spring Boot (and much more) that uses RabbitMQ as a Full External STOMP Broker and it's public on GitHub so please clone it, run the app in your machine and see the code details.
When it comes to a WebSocket connection loss, there's not much that Spring can do. Actually, the reconnection must be requested by the client side implementing a reconnection callback function, for instance (that's the WebSocket handshake flow, the client must start the handshake, not the server). There are some client side libraries that can handle this transparently for you. That's not SockJS case. In the Chat Application I also implemented this reconnection feature.
Your requirement can be divided into 2 sub tasks:
Maintain session info across multiple nodes: You can try Spring Sessions clustering backed by Redis (see: HttpSession with Redis). This very very simple and already has support for Spring Websockets (see: Spring Session & WebSockets).
Handle websockets traffic over multiple tomcat instances: There are several ways to do that.
The first way: Using a full-featured broker (eg: ActiveMQ) and try new feature Support multiple WebSocket servers (from: 4.2.0 RC1)
The second way: Using a full-feature broker and implement a distributed UserSessionRegistry (eg: Using Redis :D ). The default implementation DefaultUserSessionRegistry using an in-memory storage.
Updated: I've written a simple implementation using Redis, try it if you are interested
To configure a full-featured broker (broker relay), you can try:
public class WebSocketConfig extends AbstractWebSocketMessageBrokerConfigurer {
...
#Autowired
private RedisConnectionFactory redisConnectionFactory;
#Override
public void configureMessageBroker(MessageBrokerRegistry config) {
config.enableStompBrokerRelay("/topic", "/queue")
.setRelayHost("localhost") // broker host
.setRelayPort(61613) // broker port
;
config.setApplicationDestinationPrefixes("/app");
}
#Bean
public UserSessionRegistry userSessionRegistry() {
return new RedisUserSessionRegistry(redisConnectionFactory);
}
...
}
and
import java.util.Set;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.core.BoundHashOperations;
import org.springframework.data.redis.core.BoundSetOperations;
import org.springframework.data.redis.core.RedisOperations;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.serializer.StringRedisSerializer;
import org.springframework.messaging.simp.user.UserSessionRegistry;
import org.springframework.util.Assert;
/**
* An implementation of {#link UserSessionRegistry} backed by Redis.
* #author thanh
*/
public class RedisUserSessionRegistry implements UserSessionRegistry {
/**
* The prefix for each key of the Redis Set representing a user's sessions. The suffix is the unique user id.
*/
static final String BOUNDED_HASH_KEY_PREFIX = "spring:websockets:users:";
private final RedisOperations<String, String> sessionRedisOperations;
#SuppressWarnings("unchecked")
public RedisUserSessionRegistry(RedisConnectionFactory redisConnectionFactory) {
this(createDefaultTemplate(redisConnectionFactory));
}
public RedisUserSessionRegistry(RedisOperations<String, String> sessionRedisOperations) {
Assert.notNull(sessionRedisOperations, "sessionRedisOperations cannot be null");
this.sessionRedisOperations = sessionRedisOperations;
}
#Override
public Set<String> getSessionIds(String user) {
Set<String> entries = getSessionBoundHashOperations(user).members();
return (entries != null) ? entries : Collections.<String>emptySet();
}
#Override
public void registerSessionId(String user, String sessionId) {
getSessionBoundHashOperations(user).add(sessionId);
}
#Override
public void unregisterSessionId(String user, String sessionId) {
getSessionBoundHashOperations(user).remove(sessionId);
}
/**
* Gets the {#link BoundHashOperations} to operate on a username
*/
private BoundSetOperations<String, String> getSessionBoundHashOperations(String username) {
String key = getKey(username);
return this.sessionRedisOperations.boundSetOps(key);
}
/**
* Gets the Hash key for this user by prefixing it appropriately.
*/
static String getKey(String username) {
return BOUNDED_HASH_KEY_PREFIX + username;
}
#SuppressWarnings("rawtypes")
private static RedisTemplate createDefaultTemplate(RedisConnectionFactory connectionFactory) {
Assert.notNull(connectionFactory, "connectionFactory cannot be null");
StringRedisTemplate template = new StringRedisTemplate(connectionFactory);
template.setKeySerializer(new StringRedisSerializer());
template.setValueSerializer(new StringRedisSerializer());
template.afterPropertiesSet();
return template;
}
}
Maintain session info across multiple nodes:
Suppose we have 2 server host, backed up with load balancer.
Websockets are socket connection from browser to specific server host.eg host1
Now if host1 goes down, socket connection from load balancer - host 1 will break.
How spring will reopen same websocket connection from load balancer to host 2 ? browser should not open new websocket connection