ANCM in-proc hosting scenario

[Rick-Anderson]

aspnet/AspNetCoreModule#265

see aspnet/Announcements#288

[guardrex]

Cross-ref:

• https://blogs.msdn.microsoft.com/webdev/2018/02/28/asp-net-core-2-1-0-preview1-improvements-to-iis-hosting/
• https://github.com/shirhatti/ANCM-ARMTemplate#how-do-i-try-it%EF%BB%BF
• Standup 👉 https://youtu.be/v4xxt8f639w?t=9m59s
• No sharing of app pool in-proc. See: Can multiple sites share an application pool? #7356 (comment)
• Inproc: If there is an open connection, app_offline.htm won't work until the default shoutdownTimeLimit (90 seconds) of IIS worker process aspnet/AspNetCoreModule#243

[guardrex]

Adding the blurb from the 2.1-preview2 roadmap blog post:

Version agility

Since ANCM is a global singleton, it can’t version or ship with the same agility as the rest of the ASP.NET Core. In 2.1, we’ve refactored ANCM into two pieces: the shim and the request handler. The shim will continue to be installed as a global singleton, but the request handler will ship as part of the new Microsoft.AspNetCore.Server.IIS package which can be referenced directly by your application. This will allow you to use different versions of ANCM with different app deployments.

In-process hosting

In 2.1, we’re adding a new in-process mode to ANCM for .NET Core based apps where the runtime and your app are both loaded inside the IIS worker process (w3wp.exe). This removes the performance penalty of proxying requests over the loopback adapter. Our preliminary tests show performance improvements of around ~4.4x compared to running out-of-process. Configuring your app to use to use the in-process model can be done using web.config, and will be eventually be the default for new applications targeting 2.1:

<aspNetCore processPath="%LAUNCHER_PATH%" arguments="%LAUNCHER_ARGS%" hostingModel="inprocess" />

Alternatively, you can set a project property in your project file:

<PropertyGroup>
  <AspNetCoreModuleHostingModel>inprocess</AspNetCoreModuleHostingModel>
</PropertyGroup>