I'm new to ActiveMQ and I've done lots of googling and searches within stackoverflow as well and still not seeing a clear answer to the following question:
Can ActiveMQ be told/configured to send a published message to only ONE subscriber, from a group of subscribers, in a round-robin fashion?
Let me explain the scenario better... In our production systems we obviously run more than one server for each web app module. So let's say we have webapp module "USER" running on 10 servers. Each server, at startup will subscribe to topic "TOPIC1". Some other module (or external system) publishes a message to TOPIC1. I don't want all 10 servers to receive the exact same message. Rather I want ActiveMQ to realize that those 10 servers are subscribed to TOPIC1 as a "group" and to pick only one of them in round-robin fashion to send the message to. Can ActiveMQ be configured to do this?
Before you answer "Use message groups!" let me tell you I've read all about them and it appears to be a "sticky" load-balancing mechanism with ActiveMQ. Meaning, of those 10 servers, it will pick one (at random I guess) and from that point on any message published to TOPIC1 will always go to that server and there's no way for me to specify that servers 1-10 are participating in a "subscription group" for TOPIC1 and that they're to be given TOPIC1 messages in a round-robin fashion.
Can someone confirm or deny my assumptions? If confirm, any topic subscribe examples that would achieve the above scenario?
Thanks,
-Jac
Related
I need to handle advisories messages from the ActiveMQ.Advisory.Connection topic from one broker to another broker that is using a network connectors.
On broker A, that is linked broker B, if a client Ca is connecting, I would like the client Cb to receive the advisoiry message of A.
Is it possible ?
As I did not tried by myself, I firstly though the Advisory topics are treated as other topics but it seems not to be the case as explained in this post
The documentation on the Advisory topics does not mentions this and the above post is written by an ActiveMQ developer which seems to be a reliable source.
When connecting to Advisory topics, you have to be careful if you have authorization in place: you must give read/write access to all clients to the Advisory Topics like said in the security doc. This SO question relates exactly the issue you can have by not configuring properly the security.
On your side, I would recommend to create a network of broker with e.g. a Docker Compose and test it locally.
Further useful readings:
https://activemq.apache.org/networks-of-brokers.html#NetworksofBrokers-Networksofbrokersandadvisories
https://dzone.com/articles/how-monitor-activemq-networks
https://dzone.com/articles/active-mq-network-brokers
https://blog.christianposta.com/activemq/from-inside-the-code-activemq-network-bridges-and-demand-forward-subscriptions
https://activemq.apache.org/advisory-message.html
https://activemq.apache.org/components/cms/tutorials/handling-advisory-messages
https://docs.aws.amazon.com/amazon-mq/latest/developer-guide/ensuring-effective-amazon-mq-performance.html#network-of-brokers-configure-correctly
Q: we want publish same message in different Activemq servers. can we have any approach. like we will publish once and activemq changes will give a forward that message to another instance.
or is there any way we can do it by the activemq config changes?
There is not much context in the question but a simple Topic together with Network of brokers should do that.
The idea is that you connect multiple brokers using "network of brokers", then messages sent to a topic will be available to all clients on all brokers throughout the network.
There are a lot of corner cases when it comes to network of brokers and topics, but it should do the work.
I would like to use MassTransmit similar to NServiceBus, every publisher and subscriber has a local queue. However I want to use RabbitMQ.
So do all my desktop clients have to have RabbitMQ installed, I think so, then should I just connect the 50 desktop clients and 2 servers into a cluster?
I know the two servers must be in the same cluster. However 50 client nodes, seems a bi tmuch to put in one cluster.....Or should I shovel them or Federate them to the server cluster exchange?
The desktop machine send messages like: LockOrder, UnLock Order.
The Servers are dealing with backend hl7 messages.
Any help and advice here is much appreciated, this is all on windows machines.
Basically I am leaving NServiceBus behind, as it is now too expensive, they aiming it at large corporations with big budgets, hence Masstransmit.
However I want reliable/durable messaging, hence local queues on ALL publishers and ALL subscribers.
The desktops also use CQS to update their views.
should I just connect the 50 desktop clients and 2 servers into a cluster?
Yes, you have to connected your clients to the cluster.
However 50 client nodes, seems a bi tmuch to put in one cluster.
No, (or it depends how big are your servers) 50 clients is a small number
Or should I shovel them or Federate them to the server cluster exchange?
The desktop machine send messages like: LockOrder, UnLock Order.
I think it's better the cluster, because federation and shovel are asynchronous, it means that your LockOrder could be not replicated in time.
However I want reliable/durable messaging, hence local queues on ALL publishers and ALL subscribers
Withe RMQ you can create a persistent queue and messages, and it is not necessary if the client(s) is connected. It will get the messages when it will connect to the broker.
I hope it helps.
I have a FOSS ESB rpoject called Shuttle, if you would like to give it a spin: https://github.com/Shuttle/shuttle-esb
I haven't used NServiceBus for a while and actually started Shuttle when it went commercial. The implementation is somewhat different from NServiceBus. I don't know MassTransit at all, though. Currently process managers (sagas) have to be hand-rolled in Shuttle whereas MassTransit and NServiceBus have this incorporated. If I do get around to adding sagas I'll be adding them as a Module that can be plugged into the receiving pipeline. This way one could have various implementations and choose the flavour you like :)
Back to your issue. Shuttle has the concept of an optional outbox for queuing technologies like RabbitMQ. Shuttle does have a RabbitMQ implementation. I believe the outbox works somewhat like 'shovel' does. So the outbox would be local and sending messages would first go to the outbox. It would periodically try to send messages on to the recipients and, after a configurable number of attempts, send the message to an error queue. It can then be returned to the outbox for further attempts, or even moved directly to the recipient queue once it is up.
Documentation here: http://shuttle.github.io/shuttle-esb/
Background
My group are complete noobs with MassTransit and messaging in general. I understand the simple demos found online, but I'm confused on how to set things up for non-trivial scenarios. (many producers, many consumers, with consumers communicating back to producers)
We currently make 3rd party web service calls directly from web code via synchronous calls. Some of them are notoriously slow and unreliable to the point of browser timeouts and YSODs that aren't directly our code's fault. We want to replace these sync calls with messages and eventual consistency for retries and poison queue.
We also want to replace various scheduled/batch tasks with messaging to get closer to real time processing instead of waiting for next batch to run.
Our website runs on a farm of 6 IIS servers behind a hardware load balancer. There are 2 additional "application" servers that run the scheduled tasks. I figure we will put our new worker services on the app servers or maybe even all 8 servers.
Questions
So... The "common gotchas" section of the MT docs say that each application needs it's own address. My question is around what exactly is the definition of application in this case.
I have 6 web servers running the website. Does each of these need a unique address or can they all just be "rabbitmq://localhost/MyApp/Website". What if IIS is configured for multiple worker processes? Do each of those also need a different rabbit address?
Same question goes for my 2 application servers. If I'm running the same worker on both boxes does it need different addresses? Some stuff says if you want competing consumers to share an address, but if you want "event" type messages to be delivered to everyone they need to be different addresses.
What if you need both event (broadcast) and command (consumed once) messages sent to a worker cluster? (Multiple instances of the same workers to handle more load.)
What if I have consumers hosted in the web application directly? (I'm not sure this is a good idea to start with.)
What about request/response messages? I assume the responses should go back to the originating web server. Otherwise the MT request call will never unblock or at best timeout.
Each instance of an IServiceBus needs it's own RecieveFrom address. And yeah, if there are multiple worker processes, each should have it's own queue. You can use temporary queue for this though in web apps.
For competing consumers, each process/IServiceBus that is one of the consumes should be an exact copy. If there's an event that doesn't need to be competing, then it needs to have it's own process.
I'm attempting to set up a pub/sub system. My technical director has suggested using Rabbitmq and STOMP for the project I've been assigned.
In this system I want exchanges to be created on the server side and passed to the user to subscribe to. I want a user to subscribe to an exchange and receive information as it becomes available. I do not want the client to have the ability to subscribe to arbitrary exchanges (or routing keys for topic exchanges, I'm not sure what system I want to use yet).
For example, if someone works for a company widgetInk, when they logged in to our website they would receive a connection to the widgetInk.whatever exchange and AllUsers.whatever exchange, but that's it. if the Client side attempted to subscribe to something else they'd get an error.
I've gone through all of the RabbitMQ tutorials and I've looked through their how to section. I found this basic article on access control, but having read it three times now I still don't know if rabbitmq is a good fit for my requirements.
Can Rabbitmq be configured for my requirements? What resources can I use to learn about Rabbitmq's permission system? Has anyone build or used a system like this? Would it be in my best interest to switch to ZeroMQ or ActiveMQ?
I'd like to mention another platform you might use: Autobahn (Open-Source) or WebMQ (based on Autobahn).
WebMQ provides these features (besides a lot of other out of the box):
PubSub over WebSocket (WAMP)
Authentication of client sessions (WAMP-CRA)
fine-grained configurable authorization for topics
If you want to go the Open-source/build-your-own road, here are some tutorials. If you want an integrated, commercially supported product with Web UI for configuration/administration, please get in contact.
Disclaimer: I am creator of Autobahn/WAMP and work for Tavendo.