is it possible to broadcast a request to a specific controller to all instances?
For example I want to broadcast all request for /api/controller1 to all instances, but all others to only one instance.
Thanks!
Related
I am trying to setup akka.net cluster sharding by creating a simple project.
Project layout:
Actors - class library that defines one actor and message. Is reference by other projects
Inbound - Starts ShardedRegion and is the only node participating in cluster sharding. And should be the one hosting the coordinator too.
MessageProducer - Will host only shardedregion proxy to send messages to the ProcessorActor.
Lighthouse - seed node
Uploaded images show that the coordinator singleton is not initialized and messages send through sharedregion proxy are not delivered.
Based on the blog post by petabridge, petabridge.com/blog/cluster-sharding-technical-overview-akkadotnet/, I have excluded lighthouse, by setting akka.cluster.sharding.role, from participating in cluster sharding so that coordinator is not created on it.
Not sure what am I missing to get this to work.
This was already answered on gitter, but here's the tl;dr:
Shard region proxy needs to share the same role as a corresponding shard region. Otherwise proxy may not be able to find shard coordinator, and therefore not able to find initial location of a shard, it wants to send message to.
IMessageExtractor.GetMessage method is used to extract an actual message, that is going to be send to sharded actor. In example message extractor was used to extract string property from enveloping message, yet a receiver actor has Receive handler set for envelope, not a string.
I would like to have one server and a few clients. The Server will be my own Java application that uses CacheFactory. I will be reading all my static data from a database and populating the cache even before it is requested by any client. While the cache is getting populated in the server, it would also be spreading among all clients that are connected to the server. Once the cache population is complete, I would like to give a green signal to all clients to start requesting data. Is there something I need to do so that the server sends an event to the clients or the clients generate an event signallig the completion of cache pre-heating?
Thanks,
Yash
One way to accomplish this would be to create a region on the server and the client (say /server-ready) for notification only. The client will register interest for all keys in this region. The client will also register a CacheListener for this region.
When the server is done loading data, you can put an entry in the server-ready region. The event will be sent to the client and afterCreate() method on the CacheListener will be invoked, which could serve as a notification to your clients that the server is done populating data.
I have multiple application instances inside of Amazon EC2, each running several worker processes. What I want is each worker process to be subscribed to some notification(e.g. configuration change). This notification should be basically broadcast message, so that once it is sent - every worker receives it.
I know SQS does not support messages broadcast. Looking through similar questions/threads I see the suggestions to use SNS instead of SQS. I'm not sure this will work for me due to the following reasons:
application instances are part of autoscaling group so they can be dynamically added and removed. In this case I don't see any clear way to unsubscribe every worker(I have multiple workers per instance) once instance gets terminated, which means I'll end up with the mess of dead subscribers after some time.
protocol to use for subscription is also not clear. HTTP endpoint looks like the only option, which means my every worker should run HTTP server on its own port. It also looks I should listen only on instance public IP, which adds one more layer of complexity and insecurity.
At the moment I have a solution based on third party - I'm using 0MQ pub/sub server. But I'm looking for some out-of-box solutions AWS provides.
Thanks,
Vovan
The out-of-the-box AWS solution that comes to mind would be to create one SNS topic, and then for each instance, when the instance boots up, it would create its own SQS queue and subscribe the queue to the SNS topic, so that each individual queue gets a broadcast copy of each message you publish to SNS.
You'd want unsubscribe and delete these queues on instance termination, which could be done with lifecycle hooks.
If you didn't want to use a server to manage the processing of the lifecycle hooks (which publish the launch or termination events to SNS or SQS) you could create an AWS API Gateway endpoint to fire an AWS Lambda function, then subscribe the API Gateway endpoint to the SNS topic using https, to handle the cleanup tasks in Lambda, with no server needed.
That's several services working together and may sound a little complicated, but would be very inexpensive and require little maintenance or attention.
One more solution I've figured out is to use Amazon Kinesis.The implication here is that each subscriber has to maintain it's own checkpoint to receive only most recent notifications.
I realize this is an old thread, but I'd like to share my experience with this. Kinesis has a 5 reads/sec throttle. So if you have 10 nodes polling for events in the stream 1/sec, you're going to be in a constant state of throttling.
Kinesis looks to be primarily for massive writes with just a few readers, which doesn't quite fit a broadcast to many nodes use-case.
Redis is handy solution for broadcasting a message to all subscribers on a topic. It is convenient because it can be used as a docker container for rapid prototyping, but is also offered by AWS as a managed service for multi-node clusters.
I'm currently trying to make 3 arduinos talking to each other with ZigBee, and it's kinda working.
But I currently use AT mode on the Bees and it's a little bit harsh when I have to switch the destination address in the Coordinator of the network (1 Coordinator and 2 Routers)
Can I put the Coordinator in API mode (to make it easier to switch addresses with xbee-api for Arduino) but still be able to communicate with the AT routers and be able to send/receive data from them?
Thanks for your answer :)
Absolutely, and it's common to set up a network like that. You can have AT routers connected to "dumb" hosts that just send streams of serial data, and an API coordinator that receives from multiple routers, identifying the source of each message using the headers of the API frames, and able to send unicast messages back to individual routers or broadcast messages to all routers.
Make use of the 0x10 Transmit Request API frame to send from the coordinator to the routers. You'll receive either 0x90 or 0x91 frames (depending on the setting of ATAO).
The scenario is a follow:
I have multiple clients in which they can register themselves on a workflow server, using WCF requests, to receive some kind of notifications. The information of the notifications will be received from an external system using another receive activity. The workflow then should get the notification information and callback all registered clients using send activity and callback correlations (the clients are exposing callback interfaces implemented in there and the end-point addresses passed initially with the registration requests). "Log-running workflow service" approach is used with a persistent storage.
Now, I'm looking for some way to correlate the incoming information of the notifications received from the external system with the persisted workflow instances created previously when the registration requests, so that all clients will be notified using end-points that already passed with the registration requests. Is WF 4.0 capable of resuming and executing multiple workflow instances when the information of the notification received without storing end-points somehow manually and go though them? If yes, how can I do that?
Also, if my approach of doing so is not correct, then please advice me about the best practice of doing such system using WCF services.
Your help is highly appreciated.
When you use request correlation with workflow services the correlation key must always match a single workflow instance, you can't have multiple workflow instances react to a single message. So you either need to multicast the message using all the different correlation keys or resume you workflow instances in some other way. That other way could be to store the request somewhere, like a SQL table, and have the workflows periodically check that location if they need to notify the client.