Azure Service bus - pass parameter to message handler

Question

In Azure Service Bus I need to listen for messages arriving from multiple subscriptions from different services busses at once.
To do this I created a list that contains objects with a connection string, a topic, a subscription name and some other information (the list is called 'jobs').
For each item in this list I am then creating a different task that creates the ServiceBusClient and the processor.

            var jobs = GetAllServiceBusTopics();
            Parallel.ForEach(jobs, async job =>
            {
                var client = new ServiceBusClient(job.Environment.ServiceBusConnectionString);
                var options = new ServiceBusProcessorOptions();
                var processor = client.CreateProcessor(job.Environment.TopicName, _subscriptionName, new ServiceBusProcessorOptions());

                try
                {
                    processor.ProcessMessageAsync += MessageHandler;
                    //Pass the job object somehow to the "MessageHandler" below.
                    processor.ProcessErrorAsync += ErrorHandler;
                    await processor.StartProcessingAsync();

                    Console.WriteLine("Wait for a minute and then press any key to end the processing");
                    Console.ReadKey();

                    Console.WriteLine("\nStopping the receiver...");
                    await processor.StopProcessingAsync();
                    Console.WriteLine("Stopped receiving messages");
                }
                finally
                {
                    await processor.DisposeAsync();
                    await client.DisposeAsync();
                }
            });

And the handler that is called if a new message arrives:

    static async Task MessageHandler(ProcessMessageEventArgs args)
    {
         //I need the "job" object from my loop above here.
    }

How the concept generally works I learned on this website of Microsoft.

My first question:

1. Is this approach okay, or am I running in the wrong direction? Can I do it like this?

But even if this is okay, I have another more important task:

I need to pass the "job" object from my loop somehow to the message handler - as a parameter.
But I have currently no idea how to archvie this. Any proposals on this?

Answer 1

Is this approach okay, or am I running in the wrong direction? Can I do it like this?

Yes, you can do this. One thing to keep in mind is that you instantiate multiple ServiceBusClient instances, each causing a new connection to be established rather than using the same connection. I don't know how big the number of topics (jobs) might be but if it's large, you'll end up with connections starvation.

I need to pass the "job" object from my loop somehow to the message handler - as a parameter. But I have currently no idea how to archvie this. Any proposals on this?

That's not how ServiceBusProcessor is designed. It doesn't receive anything other than the incoming message that needs to be processed. If you need to have a job ID, that should be part of the message payload/metadata. If you need to know the entity it arrived from, you could add a subscription filter action to add a custom header with the identifier. An alternative approach would require wrapping the ServiceBusProcessor to retain the job ID/subscription identifier and use that in the event handler.