Add Kafka support

[borjaferv]

This PR contains Kafka support using Confluent.Kafka for sending and receiving events.
Use a work manager to deploy a worker with a consumer for each topic-group configured in the workflow activities.
Additionally, support for headers has been added to be able to filter specific events based on the flow.

Regarding the reception of events, it works as a first activity (Trigger) or as a suspended activity (BookMark)

Known issues

In M1 Macs (arm) the Kafka client (Confluent.Kafka) has trouble locating the library
librdkafka

So the solution I came up with was having to manually install it with the Homebrew wizard and manually compile it from source.

git clone https://github.com/edenhill/librdkafka.git  
cd librdkafka 
./configure --install-deps 
brew install  openssl zstd pkg-config 
./configure 
make 
sudo make install 

[jdevillard]

Thanks for this PR, have you take a look at the Service Bus Implementation for Request/Response Pattern using Correlation? In case you need to Send a message and receive a Response in the next activity, depending on the speed of the process you can have race condition.

On the Service Bus Activity, some lines were added :

    protected override IActivityExecutionResult OnExecute(ActivityExecutionContext context)
    {
        var message = CreateMessage(Message);


        if (!string.IsNullOrWhiteSpace(context.WorkflowExecutionContext.CorrelationId))
            message.CorrelationId = context.WorkflowExecutionContext.CorrelationId;


        return Combine(Done(), new ServiceBusActionResult(GetQueue(), GetTopic(), message, SendMessageOnSuspend));
    }

If we want to be sure that Elsa Bookmark are indexed before receiving the response, we need to delay the send on the Suspend using (in case of the ServiceBus) the ServiceBusActionResult.

elsa-core/src/activities/Elsa.Activities.AzureServiceBus/ActivityExecutionResults/ServiceBusActionResult.cs

Line 11 in c35e3a4

public class ServiceBusActionResult : ActivityExecutionResult

What do you think about that? If we think about this kind of flow using this connector, I think It could be good to implement also that code. @sfmskywalker , any thought on this point ?

[sfmskywalker]

@jdevillard Agreed, it would be good to apply the same strategy to avoid the race condition you mentioned.

[Juandavi1]

what do you think about to integrate those activities with slim ? https://github.com/zarusz/SlimMessageBus
this allow us to use diferents event bus

[sfmskywalker]

I don't know why it took me so long, but thank you for your contribution!

[sfmskywalker]

@Juandavi1 I can imagine a separate module that integrates SlimMessageBus, just like we do with Rebus and MassTransit 👍🏻

[Snotax]

@sfmskywalker In which release is this going to be available ?

[sfmskywalker]

Hi @Snotax, it will be part of the 2.10 release, which should happen soon.

[Snotax]

@sfmskywalker Awesome