In order to start a large migration, we recommend setting up a ASP.NET Core application that will proxy to the original .NET Framework Application. This set up will look like this:
flowchart LR;
external[External Traffic] --> core[ASP.NET Core Application]
core -- Adapters --- libraries
core -- YARP proxy --> framework[.NET Framework Application]
framework --- libraries[[Business logic]]
To understand how this is helpful in the migration process, please refer to the introduction. The rest of this document will provide the steps to set this up and how to proceed with an incremental migration.
- Install this experimental Visual Studio extension that will help configure the solution.
- Right click the ASP.NET Framework application and select "Migrate Project":
- This will open a menu that will offter to start a migration. Click the link to begin:
- A wizard will now appear that allows you to create a new project or select an existing project.
- After completing the wizard, you will now have an ASP.NET Core project that will proxy requests that do not exist there onto the ASP.NET Framework application.
If you have supporting libraries in your solution that you will need to use, they should be upgraded to support .NET 6. Upgrade Assistant is a great tool for this.
The adapters in this project can be used in these libraries to enable support for System.Web.HttpContext
usage that you may have in class libraries. In order to enable this in a library:
- Remove reference to
System.Web
in the project file - Add the
Microsoft.AspNetCore.SystemWebAdapters
package - Enable multi-targeting and add a .NET 6 target, or convert the project to .NET Standard
This step may require a number of projects to change depending on your solution structure. Upgrade Assistant can help you identify which ones need to change and automate a number of steps in the process.
Session is a commonly used feature of ASP.NET that shares a name with a feature in ASP.NET Core but that's where the similarity ends. Please see the documentation on session support to understand how to use it.
It is possible to share authentication between the original ASP.NET app and the new ASP.NET Core app by using the System.Web adapters remote authentication feature. This feature allows the ASP.NET Core app to defer authentication to the ASP.NET app. Please see the remote app connection and remote authentication docs for more details.
There are a number of differences between ASP.NET and ASP.NET Core that the adapters are able to smooth over. However, there are some features that require an opt-in as it will incur some cost. There are also behavior that cannot be adapted. Please see usage guidance to see a list of these.