I am confused about the function of Apache ActiveMQ.
I downloaded ActiveMQ from this link.
So I use it this way (environment: Windows 7): I start the bin/activemq.bat, then it works.
My question is: Does this mean I start a server on my machine? When I initialize the ActiveMQConnectionFactory, the broker URL is tcp://localhost:61616. But what if I want my machine to serve as a server and another machine to connect to my server?
Yes, you can use the primary box as a server and have consumers/subscribers running on other boxes (which will need to connect to the server - you will need to specify the server hostname & port for the connection to be established) - once in place, the messages on the server (topic or queue) can be consumed by the clients.
If you one have one producer and one consumer, you can look into using queues - if you have more than one consumer/subscriber, you can look into setting up a topic to which the consumers will subscribe to. Messages need to be inserted to the topic/queue as needed.
You can specify the server information in your code or preferably in the config file.
For reference to topologies:
http://activemq.apache.org/topologies.html
Also, you can choose to persist your messages or not based on your use case. Kaha DB is the preferred route (specially if performance is of concern).
Useful examples:
http://sujitpal.blogspot.com/2007/12/jms-patterns-with-activemq.html
http://vvratha.blogspot.com/2012/05/java-client-to-sendreceive-messages-for.html
Hope it helps.
Apache ActiveMQ ™ is the most popular and powerful open source messaging and Integration Patterns server
& it act like a third party server.
Apache ActiveMQ is fast, supports many Cross Language Clients and Protocols, comes with easy to use Enterprise Integration Patterns and many advanced features while fully supporting JMS 1.1 and J2EE 1.4. Apache ActiveMQ is released under the Apache 2.0 License.
ActiveMQ have the capabilities to send 100 MB single message framework and maintain 1000 concurrent connection simultaneously , for the further information you can check activemq.xml in your documentation.
Further Info at here about the ActiveMQ
Related
I need your help to suggest me how best I can achieve load balancing using the below diagram. here I am trying to create 2 machines with Master and expecting that the consumer/publisher application will use one common URL( a load-balanced one), where I should not expose the individual VM machine info and port ID. just that load balancer should take care of routing..
this is typically what we do with help of F5 load balancer or HTTP load balancer ..just wondering can be achieved over ActiveMQ and its advisable..?
on other side, I also tried configuring this way on weblogic to consume data from ActiveMQ queue
failover://(tcp://localhost:61616,tcp://localhost:61617)?randomize=true but this does not help.. or WebLogic is not understanding this format.
Messaging connections are stateful. They are not stateless like HTTP connections, and therefore cannot be load-balanced in the same way as HTTP connections. It may be possible to configure an F5 to deal with stateful messaging connections, but I can't say for sure. I'm not an expert on F5.
Both the ActiveMQ Artemis broker itself as well as the JMS client shipped with the broker have load-balancing functionality built in. There's too much to cover here so I recommend you review the clustering documentation for the relevant details.
You might also try using the broker balancer feature. It's currently experimental, but it should be ready to use in the 2.21.0 release coming in the March/April time-frame. It can act like an F5 for your messaging connections, but it can do some more intelligent things like always sending certain clients to the same node which can facilitate certain use-cases which are not possible in a traditional cluster.
The URL failover://(tcp://localhost:61616,tcp://localhost:61617)?randomize=true which are you using is for the OpenWire JMS client shipped with ActiveMQ 5.x. If you're using the core JMS client shipped with ActiveMQ Artemis then you should be using a URL like this instead:
(tcp://localhost:61616,tcp://localhost:61617)?ha=true
I am currently developing a typical IoT service. At the moment multiple devices connect to one MQTT broker (mosquitto) and my java backend also connects to the broker (Paho).
The problem i see is the following:
When i am going to have multiple instances of my java backend every backend will receive and process every message received. That`s a big issue. I just want to deliver a message to only one java backend. Anybody an idea how to deal with this problem?
Btw: Java backends will be added or removed depending on the load.
There are a couple of options
Place a queuing system between your application and the MQTT broker, possibly something like Apache Kafka
HiveMQ and IBM MessageSight brokers support (different implementations) of something called shared subscriptions. This allows messages to be shared out between more than one client. Shared subscriptions is likely to be formally added to the MQTTv5 spec which should mean that it will be added to more broker and have a standard implementation.
I am trying to setup a distributed system based on current spring-cloud release (meaning mostly Netflix OSS) using the following components
1 or more cloud config servers
1 or more Eureka servers
1 or more services using Eureka and Config Server clients
The setup above is easy enough to get going however once you start looking into setting up so that configuration changes in the cloud Config servers automatically trigger changes in the values of the actual clients, things start getting more complicated.
It is my understanding that for such a feature to work one should introduce spring-cloud-bus clients to the services which in turn will use, currently the only supported implementation, rabbitmq servers (the actual rabbitmq binaries and not some spring-boot app like eureka or Config servers) to allow change events in the Config server to be propagated to the clients automatically.
It sounds counterintuitive to setup such a system and have to hardcode addresses to rabbitmq servers in the clients (even if one will be keeping the amount of rabbitmq servers more or less static).
How is one supposed to register rabbitmq server instances in the Eureka service discovery server(s) to allow for clients to find them without having to have any knowledge about their location prior to startup?
I cannot seem to find any documentation on how this is done given that rabbitmq is not a spring-cloud component. In fact very little documentation seems to exist regarding on how the rabbitmq + eureka + spring-cloud-bus should be setup together.
I know that I am on a VERY old question, even though I think it worth a comment for people who read this in the future.
Most of the cloud services, lets take AWS as an example, have an Elastic IP solution - so you can configure IPs for RabbitMQ servers, and the IPs always belong to the RabbitMQ, no matter whether the instances change. You can re-attach the Elastic IP to different instances.
It works nearly the same with Elastic Load Balancer, which keeps its IP, so you could configure your microservices to a specific IP using Spring Cloud Config Server - and scale the RabbitMQ instances without a need to worry about configuration change.
ActiveMQ broker setup:
Broker is running on machine: hostA
Clients from different host can connect to my broker instance running on hostA, there can be any number of client from any host.
Is there a way to find out how many clients are connected to broker and also list which tell me how many connection from each host is there to my broker.
I want to do this without making assumption about number of hosts.
I can do this by using lsof command and some parsing over output, but I am in situation where I can not use this.
Is there any feature provided by ActiveMQ command line utility activemq-admin.
You can get to pretty much any Mbean attribute ActiveMQ exposes via the activemq-admin. There are no attributes or operations that give you a quick count of connections from specific clients. You will have to do some work on your end to get all the details you want, but all the raw data is there.
Examples:
Broker Stats:
activemq-admin query --objname type=Broker,brokerName=localhost
Connection Stats
activemq-admin query --objname type=Broker,brokerName=localhost,connector=clientConnectors,connectorName=<transport connector name>,connectionViewType=clientId,connectionName=*
See full doc here.
NOTE: Documentation as of this writting has not be updated to take into account the Mbean changes made in AMQ. References to Object names in examples are not correct.
You can get the object name (or example sytax) from JMX (using jconsole or visual vm for example) from the MBeanInfo. Each object name wills stat something like org.apache.activemq:type. For the script, remove the "org.apache.activemq:" and you should be in business for any thing you need from JMX via the script.
I think you may also look into using Jolokia with your broker. Although not compatible with the activemq-admin script, you can reach everything you can from the activemq-admin script, but also have access to all of the operations. In the past I've heavily used the activemq-admin script for local monitoring/command line administration of the broker, but have started converting everything to hit the Jolokia service. But again, activemq-admin will give you a way to access what you are looking for here.
I have explored the web on MULE and got to understand that for Apps to communicate among themselves - even if they are deployed in the same Mule instance - they will have to use either TCP, HTTP or JMS transports.
VM isn't supported.
However I find this a bit contradictory to ESB principles. We should ideally be able to define EndPoints in and ESB and connect to that using any Transport? I may be wrong.
Also since all the apps are sharing the same JVM one would expect to be able to communicate via the in-memory VM queue rather than relying on a transactionless HTTP protocol, or TCP where number of connections one can make is dependent on server resources. Even for JMS we need to define and manage another queue and for heavy usage that may have impact on performances. Though I agree if we have distributed and clustered systems may be HTTP or JMS will be only options.
Is there any plan to incorporate VM as a inter-app communication protocol or is there any other way one Flow can communicate with another Flow Endpoint but in different app?
EDIT : - Answer from Mulesoft
http://forum.mulesoft.org/mulesoft/topics/concept_of_endpoint_and_inter_app_communication
Yes, we are thinking about inter-app communication for a future release.
Still is not clear when we are going to do it but we have a couple of ideas on how we want this feature to behave. We may create a server level configuration in which you can define resources to use in all your apps. There you would be able to define a VM connector and use it to send messages between apps in the same server.
As I said, this is just an idea.
Regarding the usage of VM as inter-app communication, only MuleSoft can answer if VM will have a future feature or not.
I don't think it's contradictory to the ESB principle. The "container" feature is pretty well defined in David A Chappell's "Enterprise Service Bus book" chapter 6. The container should try it's best to keep the applications isolated.
This will provide some benefits like "independently deployable integration services" (same chapter), easier clusterization, and other goodies.
You should approach same VM inter-app communications as if they where between apps placed in different servers.
Seems that Mule added in 3.5 version, a feature to enable communication between apps deployed in the same server. But sharing a VM connector is only available in the Enterprise edition.
Info:
http://www.mulesoft.org/documentation/display/current/Shared+Resources#SharedResources-DefiningDomains
Example:
http://blogs.mulesoft.org/optimize-resource-utilization-mule-shared-resources/