I am designing Http trigger function. This function will be used to authenticate and to call an external API. Then get the response and pass it on to the caller(~in this case web application).
This function can be called thousand time/min(~during peak load).
I am going through event grids and having hard time deciding why to use it.
Microsoft says to safeguard your events so that it's not lost due to any reason I should use it along with my http trigger azure function.
I can very well design a queue trigger function which will process these requests in queue.
I am referring to this article of MS which says to use Event grid to gain more control on your serverless function for example:
MS Event Grid
I am going through event grids and having hard time deciding why to
use it.
I can very well design a queue trigger function which will process
these requests in queue.
I think this needs to be based on your needs. The event grid is discrete based on event triggers. And event grid has higher scalability.
If you use a queue trigger, it is not triggered based on an event, is it? All in all, it is not necessary to use event grid. Please refer to your use case for specific use.
If you want a comparison study of the messaging services you may refer to : https://tsuyoshiushio.medium.com/azure-messaging-service-in-a-picture-f8113cec54cd
https://hackernoon.com/azure-functions-choosing-between-queues-and-event-hubs-dac4157eee1c
For event grid, Azure Event Grid is an eventing service for the cloud. Azure Functions is one of the supported event handlers.
Azure Event Grid allows you to easily build applications with event-based architectures. First, select the Azure resource you would like to subscribe to, and then give the event handler or WebHook endpoint to send the event to. Event Grid has built-in support for events coming from Azure services, like storage blobs and resource groups. Event Grid also has support for your own events, using custom topics. reference
Related
I want to react to my Function App Events, specifically when a slot is swapped. I have hundreds of Function Apps which I want to Monitor but I want all the events to be handled by a single Event Handler (probably a Logic App).
I have multiple Logic Apps and Function Apps stored in a Subscription. I want to be able to use Event Grid to monitor them and react to changes. For the Logic Apps, I wanted to know every time a Logic App is saved which was fairly easy to do - I created an Event Grid which looks at Resources across a subscription and is triggered when any Resources are written successfully. And then I added some filtering so that it only reacts to Logic Apps (Microsoft.Logic/workflows) which works very well.
Where I am struggling is with the Function Apps. I want to monitor all the Function Apps and look out for any slots being swapped. I can do this by creating an event grid for each Function App but this seems wasteful to do for every singe one, whereas for the Logic App I can just have a single Event Grid which monitors everything.
What's the best way to go about this?
You can use Azure Event Grid to monitor the events from multiple Function Apps and have a single Event handler as a Logic App to process the events.
Created event grid as shown in below image by taking Endpoint type as Azure function and Endpoint as EventGridTrigger1.
After that In Event Grid Enable Subject Filtering in Filters and then take Microsoft. Web/sites/*/slots/swapped in Subject begins with field to allow the Event Grid to subscribe to all slot swapped events across all your Function Apps in the subscription.
In function app we are taking Azure Event Grid Trigger as function.
Then Create a logic App in the same subscription ,resource group and same region as function App and EventGrid taken .
When a resource event occurs Event grid trigger and Filter array action taken.
In the When a resource event occurs trigger configuration, select the Resource Type as Microsoft.EventGrid.Topics and Resource Name as you created EventGridName.
Then add an "Filter array" action to filter the events to only include events from Function Apps.
AFAIK currently the wildcard for all azure function apps is not supported so you can create as mentioned in above process or else raise a Microsoft support for this.
Basically what I understood from few Azure topics is as below:
Azure Event Hub - where data is received initially and converted into events
Service Bus- acting as a queue
Azure Event Grid - where events converted in hub are transferred here.
so the connection is like below:
Hub -> Service Bus -> Event Grid -> Pub Sub -> Storage
I understood this concept. My problem is I want data to be pushed from the event grid to GCP (subscription / topics). My question are:
How can I establish this using PUSH method?
What do I need to develop exactly?
How can I push things from grid to pubsub/subscriptions?
I found this link where data is getting published into Event Grid but I want to push data from the event grid to gcp. Can anybody explain me where am I going wrong or what exactly should I start with. I am new to this and its very confusing so I just need little bit of guidance over here.
I have below doubts:
Is there any direct subscriber option available with event grid listener? I mean can I directly link my google storage account with this listener so, whenever there is an event triggered it will be directly pushed to my GCP account(I don't have Azure account with me right now since access issue is in progress so I can't see it that's why I am asking here)
Suppose I have 20 columns in my data but I want only 16 columns to be pushed in GCP so is there any customization possible while sending data from event grid/event hub to pub/sub
If I write custom connectors code as per the links provided in the below answers then how can I run it? I mean where I can deploy those scripts on the cloud so that they will be triggered automatically whenever an event is triggered?
Can I implement webhooks in this scenario? (as an alternative to connectors), If yes then how can I do it and on which side do I need to create it?
Also, I read some articles and I came to know from a few guys that they experienced data loss in this entire process. So, what's the possibility over here and how can it be avoided
Can anybody explain me where am I going wrong or what exactly should I start with.
It's right here:
so the connection is like below:
Hub -> Service Bus -> Event Grid -> Pub Sub -> Storage
Although this might be the case, it sounds very much as if you're looking at one (very) specific scenario where data flows in this exact way.
Azure Event Hub, Azure Service Bus and Azure Event Grid can work together, but can also be used completely separate from each other.
Event Grid
The purpose of Event Grid is to enable Reactive programming. Use this when you want to react to (status) changes.
Event Hubs
Event Hubs facilitate a big data pipeline. Use this when you need telemetry and distributed data streaming.
Service Bus
The purpose of Service bus is to enable High-value enterprise messaging. Use this when you want to do something like Order processing and financial transactions.
In some cases, you use the services side by side to fulfill distinct roles. For example, an ecommerce site can use Service Bus to process the order, Event Hubs to capture site telemetry, and Event Grid to respond to events like an item was shipped.
In other cases, you link them together to form an event and data pipeline. You use Event Grid to respond to events in the other services. For an example of using Event Grid with Event Hubs to migrate data to a data warehouse, see Stream big data into a data warehouse.
Taken from the very interesting and important documentation article Choose between Azure messaging services - Event Grid, Event Hubs, and Service Bus
EDIT
My problem is I want data to be pushed from event grid to GCP (subscription / topics). So how can I establish this using PUSH method??
Possibly the simplest solution is to have an Event Grid Event trigger a webhook (which might run an Azure Function or a Google Cloud Function) which in turn puts the event/message on the GCP Topic.
Publishing messages is quite well documented. There are examples on how to do so with a REST call, command-line, C#, Go, JAVA, NodeJS, PHP, Python and Ruby.
EDIT 2
What you need to do is create an Event Grid Subscription to listen to and handle Event Grid Events.
Here's an example screenshot on how to listen for events for a specific Storage Account and call a WebHook whenever such an event occurs:
Pay attention to the "Endpoint Details": that's where you can specify to, for instance, call a webhook every time an event is triggered.
The easiest way to transfer the EventHub generated events would probably be to create an EventHub event receiver in Node.js (which you mentioned in your comments) as described here, which receives events and publishes them to Cloud Pub/Sub directly, as described in the Cloud Pub/Sub publisher documentation for Node.js.
In Azure, we have two separate messaging technologies and it's not very well documented when to use what? While EventGrid is really cool, I did not come across when to use EventGrid(scenarios) vs the Storage/ServiceBus queue? Can someone help?
E.g. if I have the following scenario :
A status of a flag changes and based on that, I want to trigger an algorithm that would do recalculations, few inserts/updates etc. in the database.
For implementing this - I can either use EventGrid or Storage Queue. How do we figure what to use in such scenario? I was looking for some kind of guidance.
Basically, Azure Event Grid handles events and Azure ServiceBus handles messages.A message is raw data produced by a service to be consumed or stored. Events are also messages (lightweigth), but they don’t generally convey a publisher intent, other than to inform.
1) If the purpose is to just to store the information ServiceBus can be used.
2) If the information received is used to trigger another service Azure Event Grid can be used.
Find more info here
https://learn.microsoft.com/en-us/azure/event-grid/compare-messaging-services
https://azure.microsoft.com/en-us/blog/events-data-points-and-messages-choosing-the-right-azure-messaging-service-for-your-data/
Events are like notifications from a service to inform the world that something happened in the domain of the publisher (similar to an email notification). There is no expectations from the publisher to have any actions taken. A message is a command you send to a specific receiver with the expectation of the message to be processed (like an asynchronous post request).
Events will work in pub/sub pattern and multiple subscribers could be configured to the events. The service that needs to react to an event will get notified by the event grid when an event occurs (http call from event grid to the receiver). The event will remain in the event grid until deletion (cleanup) and there is no garantie of keeping the original order (no FIFO).
In the other hand, messages will be added to a queue and will be deleted once the “message processor” is done with it. The messages in the queue will keep the original order (FIFO). The message processor has to pull messages from the queue.
In your scenario, you could use a combination of both. Service A sends an event “StatusChanged”, then you can configure a subscription to that event and send a message to a queue, then have your logic to process that message. This will end up with a fully async communication pattern. This is ideal to support scenarios where you processor is down or too busy. The incoming messages will simply get accumulated in the queue and eventually being processed once the service is back up and running. And without affecting the original service that sent the “StatusChanged” event..
Is there a way to make an Azure function triggerable by multiple Service Bus event queues? For example, if there is a function which logic is valid for multiple cases(event start, event end- each inserted into a different Service Bus queue) and I want to reuse it for these events can I subscribe to both of them in the Service Bus from the same function?
I was looking for an answer to this question, but so far everywhere I checked it seems to be impossible.
Azure Functions can be triggered by a single source queue or subscription.
If you'd like to consolidate multiple sources to serve as a trigger for a single function, you could forward messages to a single entity (let's assume a queue) and configure Function to be triggered by messages in that queue. Azure Service Bus support Auto-Forwarding natively.
Note that there cannot be more than 3 hops and you cannot necessarily know what the source was if message was forwarded from a queue. For subscriptions, there's a possible workaround to stamp messages.
If your goal is to simply reuse code, what about refactoring that Function to create a class which is then used in multiple functions.
If your goal is implementing events aggregation, you could probably create an Azure Durable Function Workflow that would do a fan-in on multiple Events.
Excerpt from https://github.com/Azure/azure-functions-durable-extension/issues/166:
Processing Azure blobs in hourly batches.
New blob notifications are sent to a trigger function using Event Grid trigger.
The event grid trigger uses the singleton pattern to create a single orchestration instance of a well-known name and raises an event to the instance containing the blob payload(s).
To protect against race conditions in instance creation, the event grid trigger is configured as a singleton using SingletonAttribute.
Blob payloads are aggregated into a List and sent to another function for processing - in this case, aggregated into a single per-batch output blob.
A Durable Timer is used to determine the one-hour time boundaries.
You might want to consider switching the pattern around by using only one queue but multiple Topics/Subscriptions for the clients.
Then the Function in question can be triggered by the Start-End Topic.
Some other Function can be triggered by the Working Topic, etc.
I would appreciate some help picking out the best suited Azure services for my scenario - I am just beginning with Azure services and my knowledge is pretty limited.
I have data from multiple sources, and of different shapes, coming into an Event Hub. I need to subscribe to the events from the Event Hub and, based on their format, process them and ultimately save them into an SQL Database. All components - events consumers, the SQL Database - need to be hosted in the cloud.
How would I implement this in an "Azure Orientated Architecture"?
In an off cloud application, I would have competing consumers subscribing to the Event Hub. They would be some console applications or Windows services, and each would be processing the events asynchronously (this is further simplified by the event processing being idempotent).
Ideally, the Azure equivalent of the above consumers would scale up and down automatically, so I would like to not have to use VMs that host console applications (where I would need to keep an eye on the VM's resources myself). Scaling and deployment wise they would have to behave like App Services, however I'm under the impression that those are just for web applications. I've also briefly looked at Web Jobs, but those seem to be polling data at various intervals, whereas I need a proper event subscriber that the Event Hub pushes data into.
Any help will be greatly appreciated!
Thank you.
Later Edit:
I've looked into Web Jobs and they do allow continuous
processing, hence looks like they can be used as automatically
scaling subscribers.
Ideally I would like to write the code for
the subscribers in F#. C# is the other option if that is not
available.
You can see my post regarding IoT Hub. Its basically the same for Event Hub.
(each of the examples in the post can be used on Event Hubs).
https://stackoverflow.com/a/38682324/6659347
In addition, For Event Hub you can also use Azure Function which has an Event Hub trigger - a function that will run whenever an event hub receive a new event. And it will also answer your requirement of scaling.
Make sure that if you are working with multiple consumers make use of the Event Hub Consumer Groups so each consumer can read the stream independently.
I'd say use a WebJob in combination with an EventProcessor. I wrote some demo code that can easily be transferred to a WebJob: https://github.com/DeHeerSoftware/SemanticLogging.EventHub/tree/master/SemanticLogging.EventHub.Processor
See https://azure.microsoft.com/en-us/documentation/articles/event-hubs-csharp-ephcs-getstarted/#receive-messages-with-eventprocessorhost for official documentation.
I've created a WebJob myself using this approach. Works like a charm.