I had two host every host have some queue.I want to list all queue declared by other node.
On basis of that queues, I have to perform some operation.
I didn't get any method which will list all queues from amqp server.
Thanks
Spring AMQP does not provide a direct abstraction, but RabbitMQ provides a ReST API via its management plugin.
You can use the Spring RestTemplate to query the API.
Related
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).
What benefits does spring Kafka template provide?
I have tried the existing Producer/Consumer API by Kafka. That is very simple to use, then why use Kafka template.
Kafka Template internally uses Kafka producer so you can directly use Kafka APIs. The benefit of using Kafka template is it provides different methods for sending message to Kafka topic, kind of added benefits you can see the API comparison between KafkaProducer and KafkaTemplate here:
https://kafka.apache.org/10/javadoc/org/apache/kafka/clients/producer/KafkaProducer.html
https://docs.spring.io/spring-kafka/api/org/springframework/kafka/core/KafkaTemplate.html
You can see KafkaTemplate provide many additional ways of sending data to Kafka topics because of various send methods while some calls are the same as Kafka API and are simply forwarded from KafkaTemplate to KafkaProducer.
It's up to the developer what to use. If you feel like working with KafkaTemplate is easy as you don't have to create ProducerRecord a simple send method will do all the work for you.
At a high level, the benefit is that you can externalize your properties objects more easily and you can just focus on the record processing logic
Plus Spring is integrated with lots of other components.
Note: Other options still exist like Reactor Kafka, Alpakka, Apache Camel, Smallrye reactive messaging, Vert.x... But they all wrap the same Kafka API.
So, I'd say you're (marginally) trading efficiency for convinience
I am writing a service with Spring and I am using Spring AMQP in order to connect to Rabbitmq.
I have two rabbitmq clusters, one is only for publishing messages(the messages are sent to the other cluster via the federation plugin) and the other cluster is for declaring queues that end users will consume from.
The nodes sit behind aws lb, each cluster has a lb.
I am using CachingConnectionFactory and RabbitTemplate,RabbitAdmin in my code and I want to have connections to all the nodes so I can use them.
For the cluster that will contain the queues I added to the config the queue-master-locator=random so new queues will be declared in all the nodes in the cluster even if my service does not have a connection to them.
With the cluster that publishes messages I have more of a problem because I need a direct connection in my service to each of the nodes so I will be able to separate the load between the nodes.
So my problem is, how do I create connections in my service to all the nodes in the cluster so they will all be used for declaring queues and sending messages?
Now, after I will have some sort of solution to this issue, the next issue will be what happens when a new node is added to the cluster? How can I create a connection to it and start using it as well?
I am using Rabbitmq - 3.7.9, Spring - 2.0.5, Spring AMQP - 2.0.5
Thanks alot!
There is currently no mechanism to do anything like that.
By default, Spring AMQP opens only one connection (optionally two, one for publishing, one for consuming).
Even when using CacheMode.CONNECTION, you'll get a new connection for each consumer (and connections will be created and cached on demand for producers), you won't get any control as to which node it connects to; that's a function of the LB.
The framework does provide the LocalizedQueueConnectionFactory which will try to consume from the node that hosts a queue, but it won't work with a load balancer in place.
In general, however, such optimization is rarely needed.
Are you trying to solve an actual problem you are experiencing now, or something that you perceive that might be a problem?
It is generally best not to perform premature optimization.
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 just recently started learning about spring-integration since I need to replace the a MDB(J2EE) application.
The application is composed of mostly MDB which does, splitting, aggregating and scheduling. Which, I think is the perfect criteria to use spring-integration.
I tried out some JMS examples and tried to deploy it but could not figure out how to use the jms-inbound-gateway to replace the MDB.
Is there a way to do this? Or is the only option is still to use MDB and calling the spring-integration service from the MDB's onMessage?
Use a message-driven-channel-adapter instead of an inbound gateway.
With Spring Integration, gateways are for two-way (request/reply) integraton; channel adapters are for one way integration; more like MDBs.
If you need to send some other JMS message downstream, use an outbound channel adapter later in the flow.
It's unusual to keep the MDBs, but you can do it if you really want to, and send a message to an integration flow.