I have embedded Artemis broker version 2.16.0.
Is there a way to add an acceptor and run it without having to reboot the broker?
For example, it is possible to create a queue or address in ActiveMQServerControl.
Or maybe I can add it to the broker.xml and then restart some services and the acceptor starts.
Yes, you can add an acceptor to an embedded broker at runtime and start it. Use something like this:
ActiveMQServer server;
...
server.getRemotingService().createAcceptor("myAcceptor", "tcp://127.0.0.1:61617").start();
It is possible to add/change certain things in broker.xml at runtime but an acceptor is not one of them. See the documentation for more details on that.
Related
I'm new to ArtemisMQ and absolutely don't understand the sense of connectors.
Why is connector essential, as we already specify accepter of Broker Server in broker.xml -> we know which port (it is accepter port) to send a request to if we want to connect to this server. Even if this server is part of cluster, what is a role of connector? There is also information from other part of documentation about "Clusters", but there is words about cluster connections :
The cluster is formed by each node declaring cluster connections to other nodes in the core configuration file broker.xml. When a node forms a cluster connection to another node, internally it creates a core bridge (as described in Core Bridges) connection between it and the other node, this is done transparently behind the scenes - you don't have to declare an explicit bridge for each node. These cluster connections allow messages to flow between the nodes of the cluster to balance load.
From documentation "Understanding Connectors":
connectors are used by a client to define how it connects to a server.
What does it mean "define how"?
I've already read and another question about connector, but it doesn't help me.
Additional questions:
Is connector always the same as acceptor(I've downloaded some official examples and all of them(that i've seen) have both same acceptor and connector )?
What information does connector encapsulates, if it only consists of host+port (and it is same as acceptor's (if we omit that acceptor host can me 0.0.0. or localhost))?
Why does stand-alone Broker have connector, for example by default creation ./artemis create?
What should we write in connector?
Can you give a simple example when acceptor and connector are
different?
Two important points to note:
A connector is not essential depending on your use-case. You'll find that the default broker.xml doesn't have any connector elements defined. For example, if you just run ./artemis create the generated broker.xml will not have any connector elements.
The documentation you cited is quite old (from the very first release of Artemis). You may benefit from reading the latest documentation which has been updated for clarity in many places.
As noted in both the documentation and the other Stack Overflow answer you cited, certain components in the broker need to connect to other brokers (e.g. core bridges, cluster-connections, etc.). A connector encapsulates the information necessary for these other components to make the connections they need. It's really as simple as that.
Now regarding your individual questions...
Even if this server is part of cluster, what is a role of connector?
In the case of a cluster using a broadcast-group and a discovery-group each node in the cluster needs to broadcast to all the other nodes in the cluster how the other nodes can connect to itself. It does this by broadcasting a connector which is referenced in the cluster-connection configuration. When the other nodes in the cluster receive this broadcast they take the connector information and use it to connect back to the node which broadcast it originally. In this way nodes can dynamically discover and connect to each other. It's also worth noting that in this case the connector configuration will essentially mirror one of the broker's acceptor configurations (since the connector will be used by other nodes to connect to the broadcasting node's acceptor). This is discussed further in the cluster documentation.
...connectors are used by a client to define how it connects to a server...
This bit of documentation you quoted is accurate but may be a bit confusing. Keep in mind that that a client can run anywhere, even within the broker itself. In the case of core bridges and cluster connections there is a client running in the broker which use the connector to determine how to connect to another broker. For what it's worth the updated documentation doesn't have this specific wording.
What does it mean "define how"?
A connector is the URL that the client needs to connect to the broker. The URL can simply include the host and port or it can contain lots of configuration details for the connection (e.g. SSL config).
Is connector always the same as acceptor..?
No, not always. In the case of a cluster they will be the same (or very close) for the reasons I already outlined, but in the case of a bridge they won't be the same.
What information does connector encapsulates..?
See above.
Why does stand-alone Broker have connector, for example by default creation ./artemis create?
It doesn't. See above.
What should we write in connector?
The URL needed to connect.
Can you give a simple example when acceptor and connector are different?
As mentioned previously, bridging is an example where different acceptors and connectors are used. ActiveMQ Artemis ships with a "core-bridge" example in the examples/features/standard directory which demonstrates different acceptors and connectors. The example involves 2 different brokers with one broker having a core bridge configured to send messages to the other broker. Here's the broker.xml with the bridge defined. You can see the acceptor listening on the localhost:61616 and the connector for localhost:61617. This connector points to the other broker which is listening on localhost:61617.
In case of any network issues or during triage some other issue, I would like to enable logging in the ActiveMQ Artemis broker (2.6.1) without restarting the broker to get more logging.
Currently I'm restarting the broker after enabling/disabling logging in logging.properties
logger.level=DEBUG
In ActiveMQ 5.x there is a JMX operation exposed (as mentioned in https://activemq.apache.org/how-do-i-change-the-logging). I couldn't find similar one for Artemis.
The version of ActiveMQ Artemis you're using doesn't support reloading logging configuration at runtime. This functionality was implemented via ARTEMIS-2121 so you'll need to move to 2.6.4 or 2.7.0 to get it.
Once you update your logging.properties the broker will reload it and a message will be logged that the logging configuration was reloaded. By default it may take up to 5 seconds to reload (based on the configuration-file-refresh-period in broker.xml which defaults to 5000 milliseconds).
We have a backend module which listen ActiveMQ, after changing the backend arch, we are using Mesos,Marathon and Zookeeper,
Now we want to listen Zookeeper events, if any update come to zookeeper.
Is there any Client or anything, for connect to Zookeeper and listen the Zookeeper Queues/Events.
Thanks in advance.
There are ZooKeeper bindings (client libraries) for a variety of languages, you can use those libraries to interact with ZooKeeper. The ZooKeeper Programmer's Guide is a great place to start. And here is the link to Curator.
We're using apache curator framework for this purpose. There is watch method which allow you to subscribe for specific path and listen for different events from it. Like: node created, updated, deleted or child changed...
I'd like to host apps that uses queue to communicate with each other on OpenShift.
One kind of apps - producers will put some data to the queue and another type - consumer will process the message. My question is how to implement message queue. I've thought about two approaches:
Create an app with JBoss, HornetQ and consumer and create proxy port for HornetQ, so that producers can send messages there.
Create an app with JBoss and consumer, and make a JBoss's HornetQ available to producers. It sounds a bit better for me, but I don't know if I can make queue available to producers and how it works if there are more instances of consumer on different nodes (and different JBoss instances).
I'm not sure how else to answer you besides showing you a link on how to use Wildfly. You can just use the Wildfly Cartridge:
https://www.openshift.com/quickstarts/wildfly-8
If you provide me some extra context I can try to enrich the answer a bit better. I need to know what is your problem, and what's not working.
If you just want to know how to configure Wildfly with HornetQ, the Wildfly cartridge I posted is the way to go.
We have a server app that is deployed across to server machines, each running JBOSS 4.2.2. We use JBOSS messaging with MDBs to communicate between the systems. Currently we need to start the servers in a very specific order so that JBOSS can connect properly. If a server starts and doesn't see its resources it never tries again. This is problematic and time consuming in testing when we're bouncing servers constantly. We believe that if we could specify a retry flag in JBOSS could reattempt to get the connection.
Is there a flag/config option in JBOSS that would reattempt to obtain JMS connections on failure at startup?
I am quite new to the JMS technology, so it is entirely possible that I have mixed up some terms here. Since this capability is to be used in house experimental or deprecated options are acceptable.
Edit: The problem is that a consumer starts up with no producer available and subsequently fails, never to try again. If a consumer and producer are up and the producer dies the consumer will retry for the producer to come back.
I'm 95% sure that JBoss MDBs do retry connections like that. If your MDBs are not receiving messages as you expect, I think something else is wrong. Do the MDBs depend on any other resources. Perhaps posting your EJB descriptors (META-IF/ejb-jar.xml and META-IF/jboss.xml) would help.