Hi,
We have an Http triggered Azure Function that should publish a message to a topic on an Azure ServiceBus queue and also handle the reply message (which is sent from a different Azure Function app).
Here is a very simplified example:
// Program.cs
[assembly:NServiceBusTriggerFunction("test-endpoint")]
var host = new HostBuilder()
.ConfigureFunctionsWebApplication()
.ConfigureServices(services =>
{
services.AddSingleton<MessageSenderService>();
})
.UseNServiceBus(configuration =>
{
configuration.Transport.Topology = TopicTopology.Single("test-topic");
})
.Build();
await host.RunAsync();
public class TestTriggerFunction(MessageSenderService messageSenderService,
ILogger<TestTrigger> logger)
{
[Function("TestTrigger")]
public IActionResult Run([HttpTrigger(AuthorizationLevel.Function, "get", "post")] HttpRequest req)
{
logger.LogInformation("C# HTTP trigger function processed a request.");
messageSenderService.PublishMessage();
return new OkObjectResult("Message is published.");
}
}
public class Messages
{
public class OutgoingMessage : IMessage
{
public string? Content { get; set; }
}
public class ReplyMessage : IMessage
{
public string? Content { get; set; }
}
}
public class MessageSenderService
{
public void PublishMessage()
{
var outgoingMessage = new Messages.OutgoingMessage
{
Content = "Hello from NServiceBus!"
};
// Publish to topic somehow
}
}
public class ReplyMessageHandler(ILogger<ReplyMessageHandler> logger) :
IHandleMessages<Messages.ReplyMessage>
{
public Task Handle(Messages.ReplyMessage message, IMessageHandlerContext context)
{
logger.LogInformation($"Received ReplyMessage with content: {message.Content}");
return Task.CompletedTask;
}
}
With this simplified example the easy answer is probably to inject IFunctionEndpoint into MessageSenderService and pass a FunctionContext from the Http triggered function to the PublishMessage method.
However, in our real world example the service publishing the message is nested deep within our app in a separate project; the Http triggered function sends a command to MediatR, where the handler then calls a method in another service to publish the message.
It seems a bit messy to pass the FunctionContext all the way through this chain. Is there any elegant way to publish a message when it is not done directly from the function?
We have looked into using IMessageSession, but have not been able to get it resolved with Dependency Injection - tips on how to register this in Program.cs are appreciated.