How to get a count of all telemetry messages currently available ?

Question

I am currently doing something like this to get all available telemetry (device to cloud messages).
ReadEventsAsync would block once there are no new messages. I know I can specify a time period but then that will be a wait game. Is there a way for me to determine how many messages are currently available ?

I wanted to know if there is a way for me to stop listening for messages once I have consumed all previous messages.
The only way I can think of right now is to know the no of available messages

Task.Run(async () =>
            {
                var cancellationSource = new CancellationTokenSource();
                await using EventHubConsumerClient consumer = new EventHubConsumerClient(EventHubConsumerClient.DefaultConsumerGroupName, connectionString, DeviceHubConstants.EventHubName);
                try
                {   
                    await foreach (PartitionEvent partitionEvent in consumer.ReadEventsAsync( cancellationSource.Token))
                    {
                        string data = Encoding.UTF8.GetString(partitionEvent.Data.Body.ToArray());

                    }
                }
                catch (TaskCanceledException)
                {

                }
            }).GetAwaiter().GetResult();

Answer 1

The REST API of the IoT Hub gives exactly what you need.

This goes in two steps:

1. You need some credentials for your subscription so you can construct a bearer token

Run these two powershell commands

az login
az ad sp create-for-rbac -n "testaccount"

This gives you credentials for a non-human account...

(perhaps you need to install the powershell az module first)

2. Execute this code after you filled in the variables:

Run this application with two Rest calls:

   internal class Program  
       {  
           private static void Main(string[] args)  
           {  
               var appId = "";  
               var password = "";  
               var tennant = "";  
         
               var bearer = GetBearer(tennant, appId, password);  
         
               GetQuota(bearer, "[your subscriptionId]", "[resourceGroup of your IoT Hub]", "[name of your iotHub]");  
         
               Console.WriteLine("Press a key to exit");  
         
               Console.ReadKey();  
           }  
         
           private static void GetQuota(string bearer, string subscriptionId, string resourceGroup, string iotHub)  
           {  
               var url = $"https://management.azure.com/subscriptions/{subscriptionId}/resourceGroups/{rg}/providers/Microsoft.Devices/IotHubs/{iotHub}/quotaMetrics?api-version=2018-04-01";  
         
               using var client = new HttpClient();  
               client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", bearer);  
               var req = new HttpRequestMessage(HttpMethod.Get, url);  
         
               using var res = client.SendAsync(req).Result;  
               var jsonString = res.Content.ReadAsStringAsync().Result;  
         
               Console.WriteLine(jsonString);  
           }  
         
           private static string GetBearer(string tennant, string appId, string password)  
           {  
               var nvc = new List<KeyValuePair<string, string>>  
               {  
                   new KeyValuePair<string, string>("grant_type", "client_credentials"),  
                   new KeyValuePair<string, string>("client_id", appId),  
                   new KeyValuePair<string, string>("client_secret", password),  
                   new KeyValuePair<string, string>("resource", "https://management.azure.com/")  
               };  
         
               var url = $"https://login.microsoftonline.com/{tennant}/oauth2/token";  
         
               using var client = new HttpClient();  
               var req = new HttpRequestMessage(HttpMethod.Post, url)  
               {  
                   Content = new FormUrlEncodedContent(nvc)  
               };  
         
               using var res = client.SendAsync(req).Result;  
               var jsonString = res.Content.ReadAsStringAsync().Result;  
               var json = JsonConvert.DeserializeObject<dynamic>(jsonString);  
               return json.access_token;  
           }  
       }  

As you can see, you need three other values. You can find them on the overview page of your iothub:

this will result in the right numbers:

Please accept an answer if correct. Original posters help the community find answers faster by identifying the correct answer. Here is how.

Answer 2

Hello @ SilverChips This is a great question!

Platform metrics and the Activity log are collected and stored automatically, but can be routed to other locations by using a diagnostic setting.

Metrics and logs can be routed to several locations including:

• The Azure Monitor Logs store via an associated Log Analytics workspace. There they can be analyzed using Log Analytics.
• Azure Storage for archiving and offline analysis
• An Event Hubs endpoint where they can be read by external applications, for example, third-party SIEM tools.

Please have look at Collection and routing.

Also please have a look at this Stackoverflow thread responded by Microsoft MVP @Roman Kiss and other community champs, hope this helps to guide with your query.

Please comment below if you need further help in this matter.