The SuperOffice crossmessaging capability is great for sending navigation commands (SoProtocol) to the web client, or issuing an openDocument command, from an iFrame. As we move forward towards version 12, that's not going to change.
One of the primary goals for v12 to is to run completely on .NET 8 (or higher), eliminating all dependencies on anything running .NET Framework 4.8 code. The current cross messaging command ajaxMethod depends on legacy code in .NET Framework context, and that means all ajaxMethod commands will cease to function in v12.
Are you using it? If so, please reach out (sdk@superoffice.com) and let us know. We will help you figure out how to instrument the same functionality without the ajaxMethod command.
Best regards!