I have tried to find out how I can notify multiple microservice (MS) instances via eventdriven approach if their Azure App Configuration values are changed. I have found that I via Eventgrid can listen on changes in Azure App Configuration but I don't find any built in method to distribute event to multiple instances (many MS instances)... I can choose webhook but then it will be to one instance, I can choose other eventdriven approaches as Event Hub but then I have to setup that and I wonder what is best practice for this? I don't want each MS to poll for changes rather to be notified and receive what has been changed or is there a better built in approach/strategy?
For push-based configuration updates from Azure App Configuration, the suggested approach is to forward events to a Service Bus Topic. Azure Service Bus SDK provides RegisterMessageHandler method that allows clients to register a message handler that would be triggered for every message recieved in the topic. Each instance of the microservice could set up a subscription to this Service Bus Topic and register a message handler during service initialization to receive configuration updates.
The instructions to set up a service bus topic can be found here. Details on the protocols available to subscribe to service bus topics and the required firewall configuration can be found here. Since a single topic can support up to 2000 subscriptions, this approach would allow up to 2000 service instances.
Related
I've an API (python-flask app) running on an app service in azure and want to implement a queuing system using Azure Service Bus such that requests from API are sent to a simple FIFO queue managed/ran by the service bus. Another resource in Azure will be pulling from this queue and running the jobs based on the contents of the json/payload contained in the message in the queue element.
When this element has been processed by the other resource I want to encode the job status/metadata (e.g., "finished" along with metadata such as the location where resulting data was stored). I read about such a system that makes use of the lightweight database offered by Redis, however, I'm wondering if something like this lightweight database/cache system of job status/ids/metadata is available through Azure Service Bus? I'm aware that Redis can be run standalone on a VM in Azure, however, if this can all be managed via the service bus that would be ideal. I couldn't find specifics on this being offered within Azure Service Bus and due to how this job metadata is later being accessed I cannot just push metadata messages to a new queue.
Does anyone have any insight on this or potential alternatives? If Redis can be run alongside flask within the same App Service then that would be ideal, but again I wasn't able to find anything explicit on this and it doesn't seem possible to simultaneously run a flask server/app and Redis server at the same time on an App Service.
Thanks.
I'm wondering if something like this lightweight database/cache system
of job status/ids/metadata is available through Azure Service Bus?
Azure Service Bus is a fully managed enterprise message broker, Azure Redis is a NoSQL database with steroids. It also offers queue mechanism and some other data structures.
it doesn't seem possible to simultaneously run a flask server/app and
Redis server at the same time on an App Service.
You can, but inside containers.
Please check if this can help you: https://stackoverflow.com/a/39008342/1384539
i want to develop a Game using Azure Cloud but i am not sure which ressources i could use for it. Folowing is my problem:
There is one publisher which is providing some messages. I need to find a way to add subscriber on demand. That means whenever i need more subscriber i need to add them without changing any settings on the portal.
All subscriber needs to get the published message at the same time.
Received message from the publisher needs to be deleted for all subscriber at the same time.
Is there a ressource or a way which fits theese needs?
Thanks.
Azure SignalR Service is WebSocket Gateway service that covers all your requirements.
While you could always host your own server, the service supports scaling out.
I have a local machine that reads RabbitMQ queue messages.
I wish to move it to cloud. Which Azure service can be used in this case?
I went through event hubs, but I am not sure, if it would read messages from rabbitMQ continuously.
Any suggestions for the service that should be put to use.
You should take a look at Azure Service Bus. It has got FIFO queues as well as publish/subscribe capabilities. However if using Azure managed service is not a strict requirement you can use RabbitMQ on a VM (or a cluster for high availability) as well.
UPDATE: Your response means you want a managed service. There are 2 options - if you want to go with RabbitMQ but do not want to manage the infrastructure you can go for 3rd party service provider like CloudAMQP who will manage it on your behalf. The other option is to go for Cloud native messaging - meaning if you are on Azure you change your messaging service to Azure Service Bus. This would mean changing you code as well.
I'm simply trying to work out how best to retrieve messages as quickly as possible from an Azure Service Bus Queue.
I was shocked that there wasn't some way to properly subscribe to the queue for notifications and that I'm going to have to poll. (unless I'm wrong in which case the documentation is terrible).
I got long polling working, but checking a single message every 60 seconds looks like it'll cost around £900 per month (again, unless I've misunderstood that). And if I add a redundant/second service to poll it'll double.
So I'm wondering what the best/most cost efficient way of doing it is.
Essentially I just want to take a message from the queue, perform an API lookup on some internally held data (perhaps using hybrid services?) and then perhaps post a message back to a different queue with some additional information .
I looked at worker roles(?) -- is that something that could do it?
I should mention that I've been looking at doing this with node.js.
Check out these videos from Scott Hanselman and Mark Simms on Azure Queues.
It's C# but you get the idea.
https://channel9.msdn.com/Search?term=azure%20queues%20simms#ch9Search
Touches on:
Storage Queues vs. Service Bus Queues
Grabbing messages in bulk vs. one by one (chunky vs. chatty)
Dealing with poison messages (bad actors)
Misc implementation details
Much more stuff i can't remember now
As for your compute, you can either do a VM, a Worker Role (Cloud Services), App Service Webjobs, or Azure Functions.
The Webjobs SDK and Azure Functions bot have a way to subscribe to Queue events (notify on message).
(Listed from IaaS to PaaS to FaaS - Azure Functions - if such a thing exists).
Azure Functions already has sample code provided as templates to do all that with Node. Just make a new Function and follow the wizard.
If you need to touch data on-prem you either need to look at integrating with a VNET that has site-to-site connectivity back to your prem, or Hybrid Connections (App Service only!). Azure Functions can't do that yet, but every other compute is a go.
https://azure.microsoft.com/en-us/documentation/articles/web-sites-hybrid-connection-get-started/
(That tutorial is Windows only but you can pull data from any OS. The Hybrid Connection Manager has to live on a Windows box, but then it acts as a reverse proxy to any host on your network).
To deal with Azure ServiceBus Queue easily, the best option seems to be Azure Webjob.
There is a ServiceBusTrigger that allows you to get messages from an Azure ServiceBus queue.
For node.js integration, you should have a look at Azure Function. It is built on top of the webjob SDK and have node.js integration :
Azure Functions NodeJS developer reference
Azure Functions Service Bus triggers and bindings for queues and topics
In the second article, there is an example on how get messages from a queue using Azure Function and nodejs :
module.exports = function(context, myQueueItem) {
context.log('Node.js ServiceBus queue trigger function processed message', myQueueItem);
context.done();
};
I'm looking to use Azure Service Bus with topics but need to handle the scenario where a subscriber might not be listening for a message it's interested in (e.g. server being rebooted etc.). This is the typical durable subscriber pattern as described here http://www.eaipatterns.com/DurableSubscription.html.
What I can't work out is how to apply this with Azure Service Bus and I can't seem to find any examples or discussion of this in the documentation. Is this something that Azure service bus provides or should I start looking at alternatives to Azure Service Bus?
This is built straight into Service Bus. As long as a subscription is created it is durable. You create a topic and then create one or more subscriptions. One or more consumers then listen to a subscription when they are active. If they go inactive, such as the server being rebooted, then the subscription stores the messages until a consumer comes back up and asks for one.
Service Bus would only be nondurable if you were creating and destroying subscriptions on the fly as each consumer becomes active or becomes inactive. If there are no subscriptions then messages sent to a topic are lost. Once you create a subscription, any messages sent to the topic (if they pass any filters applied) will be available on the subscription regardless if there are any active consumers using that subscription. Subscriptions exist until you remove them or, if you have the idle removal feature turned on, they surpass the idle deletion time.
You can verify this with a simple console application, or using LinqPad to set up code that does the following:
Create a topic.
Create a subscription on that topic (no filters)
Send a few messages to the topic.
In a different script or console app, create a MessageReceiver for that subscription and pull down the messages.
The messages within a subscription are durable for the life of that subscription, until they are processed (completed, etc.), they are forwarded somewhere else or they expire.
I am not sure where you looked for documentation, following are good to read:
1) http://azure.microsoft.com/en-us/documentation/articles/service-bus-dotnet-how-to-use-topics-subscriptions/
2) http://code.msdn.microsoft.com/windowsazure/Simple-Publish-Subscribe-d406eb03