Anyone had any success sending messages to Azure IOT Hub from a WASM application?

[hbraasch]

Anyone had any success sending messages to Azure IOT Hub from a WASM application?

My code works fine for the other platforms, but when running under WASM, it throws the System.PlatformNotSupportedException: Operation is not supported on this platform. exception when doing a Microsoft.Azure.Devices send.

I could not find any guidance searching through Uno Issues/Discussions.

Checking Github it acknowledges the complexities, but before going down that rabbit hole with possible AI hallucinations...

Can someone please help in case there's a working solution?

Help shall be much appreciated.

[jeromelaban]

Thanks for the question.

We haven't done IOT Hub integrations in the Uno team, but given the specific error that you're getting, it's likely that the package that you're using may need an update specifically for wasm. Could you share the full stack trace of the exception?

[hbraasch]

The trace is:

[MONO] Process terminated.
[MONO] ThreadPool.BackgroundJobHandler failed

Unhandled Exception:
System.PlatformNotSupportedException: Operation is not supported on this platform.
   at System.Net.Http.SocketsHttpHandler.get_SslOptions() in D:\a\Uno.DotnetRuntime.WebAssembly\Uno.DotnetRuntime.WebAssembly\runtime\src\libraries\System.Net.Http\src\System\Net\Http\BrowserHttpHandler\SocketsHttpHandler.cs:line 117
   at Microsoft.Azure.Devices.HttpClientHelper.CreateDefaultHttpMessageHandler(IWebProxy webProxy, Uri baseUri, Int32 connectionLeaseTimeoutMilliseconds)
   at Microsoft.Azure.Devices.HttpClientHelper.CreateDefaultClient(IWebProxy webProxy, Uri baseUri, Int32 connectionLeaseTimeoutMilliseconds)
   at Microsoft.Azure.Devices.HttpClientHelper..ctor(Uri baseAddress, IAuthorizationHeaderProvider authenticationHeaderProvider, IReadOnlyDictionary`2 defaultErrorMapping, TimeSpan timeout, IWebProxy customHttpProxy, Int32 connectionLeaseTimeoutMilliseconds)
   at Microsoft.Azure.Devices.ServiceClient..ctor(IotHubConnectionProperties connectionProperties, Boolean useWebSocketOnly, ServiceClientTransportSettings transportSettings, ServiceClientOptions options)
   at Microsoft.Azure.Devices.ServiceClient.CreateFromConnectionString(String connectionString, TransportType transportType, ServiceClientTransportSettings transportSettings, ServiceClientOptions options)
   at Microsoft.Azure.Devices.ServiceClient.CreateFromConnectionString(String connectionString, TransportType transportType, ServiceClientOptions options)
   at Microsoft.Azure.Devices.ServiceClient.CreateFromConnectionString(String connectionString, ServiceClientOptions options)
   at IotHubTester2.Models.DirectMessengerAzureIotClient.Connect() in C:\Users\Heinrich\source\repos\IotHubTester2\IotHubTester2\Models\DirectMessengerAzureIotClient.cs:line 52
   at IotHubTester2.Presentation.MainViewModel.ConnectToIotHubCommand() in C:\Users\Heinrich\source\repos\IotHubTester2\IotHubTester2\Presentation\MainViewModel.cs:line 35
   at CommunityToolkit.Mvvm.Input.AsyncRelayCommand.AwaitAndThrowIfFailed(Task executionTask) in /_/src/CommunityToolkit.Mvvm/Input/AsyncRelayCommand.cs:line 351
   at System.Threading.Tasks.Task.<>c.<ThrowAsync>b__128_1(Object state) in D:\a\Uno.DotnetRuntime.WebAssembly\Uno.DotnetRuntime.WebAssembly\runtime\src\libraries\System.Private.CoreLib\src\System\Threading\Tasks\Task.cs:line 1929
   at System.Threading.QueueUserWorkItemCallbackDefaultContext.Execute() in D:\a\Uno.DotnetRuntime.WebAssembly\Uno.DotnetRuntime.WebAssembly\runtime\src\libraries\System.Private.CoreLib\src\System\Threading\ThreadPoolWorkQueue.cs:line 1266
   at System.Threading.ThreadPoolWorkQueue.Dispatch() in D:\a\Uno.DotnetRuntime.WebAssembly\Uno.DotnetRuntime.WebAssembly\runtime\src\libraries\System.Private.CoreLib\src\System\Threading\ThreadPoolWorkQueue.cs:line 913
   at System.Threading.ThreadPool.BackgroundJobHandler() in D:\a\Uno.DotnetRuntime.WebAssembly\Uno.DotnetRuntime.WebAssembly\runtime\src\mono\System.Private.CoreLib\src\System\Threading\ThreadPool.Browser.Mono.cs:line 130
Aborted()
RuntimeError: Aborted(). Build with -sASSERTIONS for more info.
Stack trace:
 >  at abort (http://localhost:5000/package_dcfd50348c14863b98a01db586afc106558de65e/dotnet.native.js:8:9137)
 >    at _abort (http://localhost:5000/package_dcfd50348c14863b98a01db586afc106558de65e/dotnet.native.js:8:97733)
 >    at http://localhost:5000/package_dcfd50348c14863b98a01db586afc106558de65e/dotnet.native.wasm:wasm-function[1787]:0x97b09
 >    at http://localhost:5000/package_dcfd50348c14863b98a01db586afc106558de65e/dotnet.native.wasm:wasm-function[1828]:0x99414
 >    at http://localhost:5000/package_dcfd50348c14863b98a01db586afc106558de65e/dotnet.native.wasm:wasm-function[354]:0x20314
 >    at http://localhost:5000/package_dcfd50348c14863b98a01db586afc106558de65e/dotnet.native.wasm:wasm-function[250]:0x1c426
 >    at http://localhost:5000/package_dcfd50348c14863b98a01db586afc106558de65e/dotnet.native.wasm:wasm-function[243]:0xf4b5
 >    at http://localhost:5000/package_dcfd50348c14863b98a01db586afc106558de65e/dotnet.native.wasm:wasm-function[311]:0x1ef9d
 >    at http://localhost:5000/package_dcfd50348c14863b98a01db586afc106558de65e/dotnet.native.wasm:wasm-function[332]:0x1f79f
 >    at http://localhost:5000/package_dcfd50348c14863b98a01db586afc106558de65e/dotnet.native.wasm:wasm-function[222]:0xd201

I think it's a CORS issue, but I do not know if one can enable CORS on the IOT hub. I'm hoping someone might have solved it by now.

Thanks for the help. Much appreciated.

[jeromelaban]

Thanks. This is not a CORS issue, this is really because the ServiceClient is trying to change unsupported options on the HttpMessageHandler.

By the looks of the stack, it's likely that you can change the HttpMessageHandler builder (CreateDefaultHttpMessageHandler suggests that there's a way to override it). You may want to create your own handler without the call that does not work on Wasm.

[hbraasch]

You are correct, its in the library. I've downloaded the source and traced into it. The problem lies with:

The Uno implementation for HttpClient (the WASM version) does not allow the additional parameters in the constructor. By replacing (2) below with (1) below, I got it to create a ServiceClient which works.

Thereafter, I think I finally ran into a CORS problem (getting an exception "Failed to fetch"), but for that I need to resolve with the Azure people.

Back to HttpClient...

Wouldn't say its a bug, but more a shortcoming. Do you think the devs can update the wasm's HttpClient to either:

• Incorporate constructing it with the provided MessageHandler

• Not throw an exception, just ignore it (with a warning)

The problem is that, without these changes, I cannot use the library Nuget as is. I need to add the complete library project to my solution and that makes it real messy.

What do you suggest?

Thanks for the help

[jeromelaban]

This would be a good question to ask to the .NET team in the dotnet/runtime repository, as Uno does not have any control in that area, but they'll likely not alter the BCL's behavior.

In general, libraries that do networking should provide ways to provide both an HttpClient, as well has HttpMessageHandler, so that scenarios like the one in question can be adjusted. It may also be a good idea to mention to the Azure IOT library maintainers to allow for that and/or make a PR to enable it.