Any Example of WebJob using EventHub? - azure

Question

I've tried to come up with something from the example in the WebJobsSDK gitHub
var eventHubConfig = new EventHubConfiguration();
string eventHubName = "MyHubName";
eventHubConfig.AddSender(eventHubName,"Endpoint=sb://test.servicebus.windows.net/;SharedAccessKeyName=SendRule;SharedAccessKey=xxxxxxxx");
eventHubConfig.AddReceiver(eventHubName, "Endpoint=sb://test.servicebus.windows.net/;SharedAccessKeyName=ReceiveRule;SharedAccessKey=yyyyyyy");
config.UseEventHub(eventHubConfig);
JobHost host = new JobHost(config);
But I'm afraid that's not far enough for someone of my limited "skillset"!
I can find no instance of JobHostConfiguration that has a UseEventHub property (using the v1.2.0-alpha-10291 version of the Microsoft.AzureWebJobs package), so I can't pass the EventHubConfiguration to the JobHost.
I've used EventHub before, not within the WebJob context. I don't see if the EventHostProcessor is still required if using the WebJob triggering...or does the WebJob trigger essentially act as the EventHostProcessor?
Anyway, if anyone has a more complete example for a simpleton like me that would be really sweet! Thanks

Answer 1

From the documentation here, you should have all the information you need.
What you are missing is a reference of the Microsoft.Azure.WebJobs.ServiceBus.1.2.0-alpha-10291 nuget package.
The UseEventHub is an extension method that is declared in this package.
Otherwise your configuration seems ok.
Here is an example on how to receive or send messages from/to an EventHub:
public class BasicTest
{
public class Payload
{
public int Counter { get; set; }
}
public static void SendEvents([EventHub("MyHubName")] out Payload x)
{
x = new Payload { Counter = 100 };
}
public static void Trigger(
[EventHubTrigger("MyHubName")] Payload x,
[EventHub("MyHubName")] out Payload y)
{
x.Counter++;
y = x;
}
}

Answer 2

EventProcessorHost is still required, as the WebJob just provides the hosting environment for running it. As far as I know, EventProcessorHost is not integrated so deeply into WebJob, so its triggering mechanism cannot be used for processing EventHub messages. I use WebJob for running EventProcessorHost continuously:
public static void Main()
{
RunAsync().Wait();
}
private static async Task RunAsync()
{
try
{
using (var shutdownWatcher = new WebJobsShutdownWatcher())
{
await Console.Out.WriteLineAsync("Initializing...");
var eventProcessorHostName = "eventProcessorHostName";
var eventHubName = ConfigurationManager.AppSettings["eventHubName"];
var consumerGroupName = ConfigurationManager.AppSettings["eventHubConsumerGroupName"];
var eventHubConnectionString = ConfigurationManager.ConnectionStrings["EventHub"].ConnectionString;
var storageConnectionString = ConfigurationManager.ConnectionStrings["EventHubStorage"].ConnectionString;
var eventProcessorHost = new EventProcessorHost(eventProcessorHostName, eventHubName, consumerGroupName, eventHubConnectionString, storageConnectionString);
await Console.Out.WriteLineAsync("Registering event processors...");
var processorOptions = new EventProcessorOptions();
processorOptions.ExceptionReceived += ProcessorOptions_ExceptionReceived;
await eventProcessorHost.RegisterEventProcessorAsync<CustomEventProcessor>(processorOptions);
await Console.Out.WriteLineAsync("Processing...");
await Task.Delay(Timeout.Infinite, shutdownWatcher.Token);
await Console.Out.WriteLineAsync("Unregistering event processors...");
await eventProcessorHost.UnregisterEventProcessorAsync();
await Console.Out.WriteLineAsync("Finished.");
}
catch (Exception ex)
{
await HandleErrorAsync(ex);
}
}
}
private static async void ProcessorOptions_ExceptionReceived(object sender, ExceptionReceivedEventArgs e)
{
await HandleErrorAsync(e.Exception);
}
private static async Task HandleErrorAsync(Exception ex)
{
await Console.Error.WriteLineAsync($"Critical error occured: {ex.Message}{ex.StackTrace}");
}