PowerToys/doc/devdocs/settingsv2/runner-ipc.md

Inter-Process Communication with Runner

The Settings v2 process uses two way IPC to communicate with the runner process.

Initialization

• On the settings' side, the two way IPC delegates are contained with the ShellPage.xaml.cs file. The delegates are static and the views for all the powerToys send the ipc information to the viewmodels as ShellPage.DefaultSndMSGCallBack.
• These delegates are initialized within the Mainwindow.xaml.cs file in the Settings.Runner project.

Types of IPC delegates

• There are three types of delegates for the settings to communicate with the runner:

1. SendDefaultMessage - This is used by all the viewmodels to communicate changes in the UI to the runner so that the information can be dispatched to the modules.
2. RestartAsAdmin
3. CheckForUpdates

Sending information to runner

• The settings process communicates with the runner by using the delegates defined within the ShellPage.xaml.cs file.
• Depending on the type of object sending the information, the json is created accordingly.
• If any information has been modified by the user in the GeneralSettings page, then the json file sent to the runner has the name set to general, whereas if any information has been modified by the user in any powertoy related settings page, the name of the json file being communicated with the runner is set to powertoy.

Receiving information from runner

• The ShellPageobject has a IPCResponseHandleList which is a list of functions which handle IPC responses.

// receive IPC Message
Program.IPCMessageReceivedCallback = (string msg) =>
{
    if (ShellPage.ShellHandler.IPCResponseHandleList != null)
    {
        try
        {
            JsonObject json = JsonObject.Parse(msg);
            foreach (Action<JsonObject> handle in ShellPage.ShellHandler.IPCResponseHandleList)
            {
                handle(json);
            }
        }
        catch (Exception)
        {
        }
    }
};

• Whenever any information is sent from the runner each of the functions in the handle list perform their action on that json object.
• One example of where information sent from the runner is being processed by the settings is in GeneralPage.xaml.cs when the user clicks the check for updates button. The information displayed after, such as the user has the latest version installed is a result of this handle.