Writes to Remote Session failing because session host application does not support ReadEntityBodyMode.Classic

[TJKenny]

Describe the bug

Writes to the session made by a .Net8 application do not persist in the session server hosted by a Classic Framework 4.8.1 Web Forms application

To Reproduce

I can share source code but I'd like to start by describing the situation and seeing if anyone can spot an obvious issue. Im hoping someone recognizes the very specific errors I'm getting below.

Mostly my code matches whats in this example anyway, except that Im migrating to MVC/.NET8 rather than Blazor:

https://github.com/dotnet/systemweb-adapters/tree/main/samples/WebFormsToBlazor

My WebForms app is OLD and I suspect its missing some key setup but I can't figure it out.

• I am able to run the Session server on the WebForms side and I have the Client going on the .NET8 side.

• I am able read the session on the .NET8 side but...

The writes are failing and it's not a ReadOnly session

Here is my controller in .Net8:

[Session(IsReadOnly = false)]
public class HelloWorldController : Controller
{
	public string Welcome()
	{
		// This retrieves an item that was set in the Session server on the WebForms app.  It works.
		object setOnWebFormsSide = System.Web.HttpContext.Current.Session["SetOnWebFormsSide"];

		// This should set a value in the Session server on the WebForms app.  It doesn't work.
		System.Web.HttpContext.Current.Session["Message"] = "Hello";

		return "Hi";
	}}

I got the debug symbols for the systemweb-adapters package to trace what happens after I set a session value on the NET8 side:

Inside RemoteAppSessionStateManager.SetOrReleaseSessionData() the line _backchannelClient.SendAsync() returns "StatusCode: 404, ReasonPhrase: 'Not Found'" (which is the result passed up from the nested System.Net.Http.HttpClient.SendAsync() call that it makes):

At first, I could see that my ASP.NET app does not accept PUT requests at all.

I can get it to accept PUT requests by copying the <handlers> section of the web.config from the example linked above, specifically this line:

<add name="ExtensionlessUrlHandler-Integrated-4.0" path="*." verb="*" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" />

But now the same _backchannelClient.SendAsync() call from above returns "StatusCode: 500, ReasonPhrase: 'Internal Server Error', ..."

This happens because inside the method:

System.Web.HttpRequest.GetInputStream(bool,bool)

.. it throws an exception "Incompatible_with_input_stream" when it sees the ReadEntityMode is ReadEntityMode.Classic:

Anyone know what this last thing is about?

It feels like old Webforms apps couldn't handle buffered requests and maybe I need to do some extra setup step to make it support this? Or I have pipelines setup somewhere that are forcing non-buffered streams but Im not sure where to look. The WebForms app is very large and hosts web pages and WCF services Im trying to migrate over. There is a lot in the config files and I don't know where to look.

My WebForms app did not have either the Microsoft.AspNet.Web.Optimization.WebForms or Microsoft.Web.Infrastructure packages like the example but adding these doesn't change the situation.

Any ideas on where to start?

Exceptions (if any)

See the HttpException thrown in the last screenshot. I think this is from the HttpRequest code inside the WebForms application.

Further technical details

Please include the following if applicable:

ASP.NET Framework Application:

• Technologies and versions used (i.e. MVC/WebForms/etc): WebForms/WCF
• .NET Framework Version: 4.8.1 and .Net Standard 2.0)
• IIS Version: IIS Express (WebForm application was originally IIS so there could be unknown cruft). Its also hosted as https on development machines.
• Windows Version: 10

ASP.NET Core Application:

• Targeted .NET version: 8
• .NET SDK version: 8.0.400

[twsouthwick]

<add name="ExtensionlessUrlHandler-Integrated-4.0" path="*." verb="*" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" />

This is required, so that's expected. It should be added by the nuget package, though; glad you found it :)

.. it throws an exception "Incompatible_with_input_stream" when it sees the ReadEntityMode is ReadEntityMode.Classic:

Hmmm... didn't realize that would throw. That's unfortunate. Can you try the fix in #550?