I'm using websockets to build a chat server in springboot. Now my application lacks any kind of Spring Security information since it is intended to only act as a channel between two desktop clients.
So currently I'm able to broadcast messages to all clients, however, I would like to know, is it possible to create dynamic queues when a client connects to other user, (a queue is created and they both subscribe to same queue). The queue exists until one of the client disconnects.
I'm using SimpleMessageBroker priovided with Spring.
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I have recently developed a simple messaging application with Spring Boot and Spring Security. The application takes in 2 users - user A and user B. Once, user A performs a specific task a notification is sent to user B. Currently I am doing this by adding a Spring Messaging dependency and SockJS and it works great.
Here is where I am confused and hoping to receive some guidance. I realize there are many tutorials that speak about RabbitMQ and ActiveMQ. From what I understand, they are message brokers. May I ask what is the difference between SockJS and RabbitMQ/ActiveMQ? And do I need RabbitMQ/ActiveMQ in my current application together with SockJS?
SockJS is JavaScript based WebSocket client library that runs in a browser. It can be used to send messages to or receive messages from a broker.
Both RabbitMQ and ActiveMQ are message brokers, examples of message-oriented middleware. They both support WebSocket clients which use a messaging protocol (e.g. STOMP or AMQP). Brokers receive messages from and dispatch messages to clients.
You haven't really provided enough information to determine whether or not you actually need to use either RabbitMQ or ActiveMQ in your current application given that it's already working as it is.
We are using microservice architecture in our project. We deploy each service to a cluster by using Kubernetes. Services are developed by using Java programming language and Spring Boot framework.Three replicas exist for each service. Services communicate with each other using only events. RabbitMQ is used as a message queue. One of the services is used to send an email. The details of an email are provided by another service with an event. When a SendingEmail event is published by a service, three replicas of email service consume the event and the same email is sent three times.
How can I prevent that sending emails by other two services?
I think it depends on how you work with Rabbit MQ.
You can configure the rabbit mq with one queue for these events and make spring boot applications that represent the sending servers to be "Competing" Consumers.
If you configure it like this, only one replica will get an event at a time and only if it fails to process it the message will return to the queue and will become available to other consumers.
From what you've described all of them are getting the message, so it works like a pub-sub (which is also a possible way of work with rabbit mq, its just not good in this case).
I have 2 spring boot applications
On-premise teller application
Cloud based multi-tenant application that aggregates data from all teller applications
The teller application has to work offline(if connectivity is down) as well. What is the best approach to broadcast events from the teller application to the cloud. I would not prefer to implement code to persist events.
What is the best approach? ReST/message broker or some other approach. If using a message broker, will the spring cloud stream abstraction queue events when the connection to the broker is down and retry.
I would go with the message broker (rabbit, kafka) and spring-cloud-stream, since your use case was exactly what/how it was designed.
The microservcice (your app) is a consumer of the broker, that is: it can publish to and/or consume events from the broker. If the app is down the broker is up and potentially collecting events destined to the down app. Once app is up it consumes queued up events and so on.
I'll stop here given the general nature of your question but feel free to follow up with more details.
I want to know the major difference between VM and JMS component of Mule ESB. Can someone help me to know it.
As per Mule documentation, VM transport is for intra-JVM communication between Mule flows. So, that means when you use a VM in your flow, you can communicate between different flows in the application.
A flow containing VM inbound cannot be called externally from external application as thus the flow is equivalent to a private flow used within the application. By default uses in-memory queues.
Please go through the documentation :- https://docs.mulesoft.com/mule-user-guide/v/3.8/vm-transport-reference
On the other hand as per Mule documentation, JMS is an external host, allows communication between different components of a distributed application and JMS transport lets you easily send and receive messages to queues and topics for any message service which implements the JMS specification.
A flow, which has JMS inbound can be called from externally unlike VM. Documentation is here :- https://docs.mulesoft.com/mule-user-guide/v/3.8/jms-transport-reference
Within the application, if you send the control from one flow to another flow we use VM.VM can be used as both inbound and outbound.
Outside the application, for example, A application want to send something to B application(external application) there we use JMS.
I've a Spring boot Application for Web sockets. I'm not using Stomp Web socket.
Is there way we can share web socket sessions across multiple instance of micro service.
Is there a way we can save websocket session in Redis or cassandra?
My use case is, i've multiple instance of my micro service is running, which is listening a kafka queue, so when a message received, i need to send it to the client using web socket session.I'm saving the session in the micro service as a MAP. My problem is any one of my micro service is getting the message, if the session is not available with that micro service the message is not going to the client.
If i'm able to save the websocket sesssion in REDIS or Cassandra, i can query the session and sent to the client.
I can't use Stomp web socket as per the requirement, it has to be normal websocket.
You can't. You have to implement some sort of routing from whatever receives the kafka message, to your micro service.
One simple way to do it would be to store in any datastore (mongo, redis, etc) the IP of the service instance for a given client. That way when you get the message from kafka, an you know who is it for, you lookup which machine has the websocket session for that client. Then you call some http endpoint on that IP that you implement to relay a message for a session it's handling.