Getting next message in an Azure Service Bus Subscription with an Azure Function, with an HTTP Trigger - azure

Question

I want to create an Azure Function that will fulfill the following requirements:
Trigger upon an HTTP request
Looks at an Azure Service Bus Subscription and gets the next message based on a set of filters specified in the HTTP Request.

Answer 1

If you are using C# you can do something like this:
using System;
using System.IO;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.Http;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Logging;
using Newtonsoft.Json;
using Microsoft.Azure.ServiceBus;
using Microsoft.Azure.ServiceBus.Core;
namespace HttpTriggerSBRead
{
public static class ReadSBOnHttpTrigger
{
const string ServiceBusConnectionString = "{service bus connection string}";
const string TopicName = "{name of your topic}";
const string SubscriptionName = "{name of your subscription}";
[FunctionName("ReadSBOnHttpTrigger")]
public static async Task<IActionResult> Run(
[HttpTrigger(AuthorizationLevel.Anonymous, "get", "post", Route = null)] HttpRequest req,
ILogger log)
{
string filter = req.Query["filter"];
string requestBody = await new StreamReader(req.Body).ReadToEndAsync();
dynamic data = JsonConvert.DeserializeObject(requestBody);
filter = filter ?? data?.filter;
SubscriptionClient sqlFilterOnlySubscriptionClient = new SubscriptionClient(ServiceBusConnectionString,
TopicName, SubscriptionName);
await sqlFilterOnlySubscriptionClient.AddRuleAsync(new RuleDescription
{
Filter = new SqlFilter(filter),
Name = filter
});
await ReceiveMessagesAsync(SubscriptionName, log);
await sqlFilterOnlySubscriptionClient.RemoveRuleAsync(filter);
return filter != null
? (ActionResult)new OkObjectResult($"{filter}")
: new BadRequestObjectResult("Please pass a filter on the query string or in the request body");
}
static async Task ReceiveMessagesAsync(string subscriptionName, ILogger log)
{
string subscriptionPath = EntityNameHelper.FormatSubscriptionPath(TopicName, subscriptionName);
IMessageReceiver subscriptionReceiver = new MessageReceiver(ServiceBusConnectionString, subscriptionPath, ReceiveMode.ReceiveAndDelete);
log.LogInformation($"{DateTime.Now} :: Receiving Messages From Subscription: {subscriptionName}");
var receivedMessage = await subscriptionReceiver.ReceiveAsync(TimeSpan.FromSeconds(30));
if (receivedMessage != null)
{
log.LogInformation($"Lable Property = {receivedMessage.Label}");
}
log.LogInformation($"{DateTime.Now} :: Messages From Subscription: {subscriptionName}");
}
}
}
To use it you need to pass in the filter parameter to your function. For example something like this:
http://localhost:7071/api/ReadSBOnHttpTrigger?filter=sys.Label=%27test%27 or http://localhost:7071/api/ReadSBOnHttpTrigger?filter=sys.To=%27test%27
Just for the reference, I used this code as source with some small modifications:
https://github.com/Azure/azure-service-bus/tree/master/samples/DotNet/GettingStarted/Microsoft.Azure.ServiceBus/TopicSubscriptionWithRuleOperationsSample