Sidio.Functions.Worker.ServiceBus

A collection of useful service bus features for .NET isolated middleware.

Installation

Add the NuGet package to your project.

Middleware

Middleware template

The abstract class ServiceBusMiddlewareBase supports the following methods:

• BeforeInvocationAsync: executed before the invocation of the FunctionExecutionDelegate.
• AfterInvocationAsync: executed after the invocation of the FunctionExecutionDelegate, unless an exception is thrown.
• AlwaysAfterInvocation: executed after the invocation of the FunctionExecutionDelegate, regardless of an exception being thrown.
• OnExceptionAsync: executed when an exception is thrown during the invocation of the FunctionExecutionDelegate. Return true when the exception is handled, false when the exception should be rethrown.

ExceptionInsightMiddleware

The ExceptionInsightMiddleware adds exception details to a dead-lettered message:

• Dead letter reason
• Exception message

Please note: it is currently not possible to read the maximum delivery count setting of a queue or topic. Therefore, you have to configure the ExceptionInsightMiddlewareOptions manually and ensure the maximum delivery count is set to a value equal or less than the service bus setting.

Usage

var host = new HostBuilder()
    .ConfigureFunctionsWorkerDefaults(
        workerApplication =>
        {
            workerApplication.UseExceptionInsightMiddleware();
        })
    // ...

ScheduledRetryMiddleware

Usage

The ScheduledRetryMiddleware is an extension of the ExceptionInsightMiddleware, you should not register both middleware.

var host = new HostBuilder()
    .ConfigureFunctionsWorkerDefaults(
        workerApplication =>
        {
            workerApplication.UseScheduledRetryMiddleware();
        })
    // ...

Configuration

• MaxDeliveryCount: the maximum number of delivery attempts before a message is dead-lettered.
• BackoffMode: the backoff mode to use for rescheduling messages.
• BackoffInSeconds: the number of seconds to wait before rescheduling a message.

Service Bus client provider

It's possible to use a custom IServiceBusClientProvider to provide a ServiceBusClient for sending messages:

services.AddScoped<IServiceBusClientProvider, MyServiceBusClientProvider>();

Manual dead-letter resubmission

When you want to resubmit a dead-lettered message manually, make sure the ScheduledRetryMiddleware.DeliveryAttempts property is removed.

Extensions

FunctionContext extensions

GetServiceBusTrigger

Gets the ServiceBusTriggerAttribute from the function context:

var attribute = functionContext.GetServiceBusTrigger();

IsServiceBusTrigger

Determines whether the function is a service bus trigger. Can be used when registering middleware:

functionsWorkerApplicationBuilder.UseWhen<MySerivceBusMiddleware>(context => context.IsServiceBusTrigger());

Known issues

• The ExceptionInsightMiddleware and ScheduledRetryMiddleware only support a trigger with a ServiceBusRecievedMessage binding. A trigger-binding to a string is not supported.