Application launch monitoring

What it is

• In-memory helper that correlates “I launched an app” with “that app connected back.”
• Register a launch, then report a connection. It matches 1:1 in FIFO order and handles timeouts.
• When a launched app fails to connect, OnTimeout is invoked.
• Thread-safe and IDisposable.
• Uses a composite key: MVID + Platform + IsDebug. MVID is the module version ID of the app’s head assembly (unique per build). More info: https://learn.microsoft.com/en-us/dotnet/api/system.reflection.module.moduleversionid

How to use

1) Create the monitor (optionally with callbacks and a custom timeout)

using Uno.UI.RemoteControl.Server.AppLaunch;

var options = new ApplicationLaunchMonitor.Options
{
    // Default is 60s
    Timeout = TimeSpan.FromSeconds(30),
    OnRegistered = ev => logger.LogInformation($"Launch registered: {ev.Mvid} ({ev.Platform})"),
    OnConnected = ev => logger.LogInformation($"Connected: {ev.Mvid} ({ev.Platform})"),
    OnTimeout   = ev => logger.LogWarning($"Timed out: {ev.Mvid} ({ev.Platform})")
};

using var monitor = new ApplicationLaunchMonitor(options: options);

2) When you start a target app, register the launch

// New signature includes IDE and Uno plugin version
monitor.RegisterLaunch(mvid, "Wasm", isDebug: true, ide: "VisualStudio", plugin: "uno-vs-extension-1.2.3");

3) When the app connects back to the dev server, report the connection

monitor.ReportConnection(mvid, "Wasm", isDebug: true);

The monitor pairs the connection with the oldest pending launch for the same (mvid, platform, isDebug). If no connection arrives before the timeout, OnTimeout is invoked.

Notes

• Platform matching is case-sensitive ("Wasm" != "wasm").
• A null platform is normalized to "Unspecified".
• Registrations are consumed in FIFO order per key.
• Always dispose the monitor (use using as shown).

Analytics events

Events emitted by the monitor are prefixed with uno/dev-server/app-launch/. See Telemetry.md in the .Host project for details.

Integration points (IDE, transport, HTTP)

The dev-server can receive registration and connection events through multiple channels:

• IDE → DevServer: AppLaunchRegisterIdeMessage (scope: AppLaunch) carrying MVID, Platform, IsDebug. Triggers RegisterLaunch.
• Runtime → DevServer over transport (WebSocket by default) (scope: DevServerChannel): AppLaunchMessage with Step = Launched. Triggers RegisterLaunch.
• HTTP GET → DevServer: GET /applaunch/{mvid}?platform={platform}&isDebug={true|false}. Triggers RegisterLaunch.

Connections are reported by the runtime after establishing the transport connection (WebSocket by default):

• Runtime → DevServer over transport (WebSocket by default) (scope: DevServerChannel): AppLaunchMessage with Step = Connected. Triggers ReportConnection.

If no matching Connected message arrives before timeout, a timeout event is emitted.

Testing / time control

• The constructor accepts an optional TimeProvider which the monitor uses for timeout scheduling. Tests commonly inject Microsoft.Extensions.Time.Testing.FakeTimeProvider and advance time with fake.Advance(...) to trigger timeouts instantly.
• Example for tests:

var fake = new FakeTimeProvider(DateTimeOffset.UtcNow);
using var monitor = new ApplicationLaunchMonitor(timeProvider: fake, options: options);
// register, then fake.Advance(TimeSpan.FromSeconds(11)); // triggers timeout callbacks

Where it lives

• Project: Uno.UI.RemoteControl.Server
• Folder: AppLaunch
• File: ApplicationLaunchMonitor.cs (implementation)