A core set of widgets, types, and services to create Fermilab applications.

Features

• Provides a ControlsRouterApp widget to create a base, scaffold widget that has a standardized theme.
• Provides a class that accesses the Fermilab GraphQL API.
• Provides a widget that authenticates users.

Getting started

The latest, stable branch is v0.3, which is managed by the main branch. To add this package to your application, add this dependency to your pubspec.yaml file:

flutter_controls_core:
    git:
        url: https://github.com/fermi-ad/flutter-controls-core.git
        ref: main

NOTE: This project is under very active development so calling this the "stable" branch is a stretch. With each pull request, we will create a tag to point to it. If the HEAD of main produces a regression, you can temporarily use a tag as the git "ref:" parameter to get back to a more reliable version.

Mobile Targets

If you are building a native, mobile app, you need to add network permissions in order to use the GraphQL interface (this library is only useful when using the network!)

For Android targets, add the following tag to your AndroidManifest.xml file, immediately after the opening manifest tag:

<uses-permission android:name="android.permission.INTERNET" />

For iOS targets, you need to open the .codeproj file in XCode and add the permissions for network access in the application's profile. The appropriate .xml files will be modified.

Using GraphQL

GraphQL support has been removed from this package. Your application now must specify which GraphQL endpoints it wants to use. For instance, if your app needs to read or set control system devices, it will need the ACSys GraphQL API. In pubspec.yaml, you'll add

dependencies:
  flutter_gql_acsys:
    git:
      url: https://github.com/fermi-ad/flutter-gql-acsys.git
      ref: main

  flutter_controls_core:
    git:
      url: https://github.com/fermi-ad/flutter-controls-core.git
      ref: main

and where your application constructs the StandardApp, you specify the provider of the GraphQL API:

final appTitle = "My App";

class App extends StatelessWidget {
  const App();

  @override
  Widget build(final BuildContext context) => StandardApp(
    title: appTitle,
    providers: [ACSysProvider.factory()],
    appBar: AppBar(title: const Text(appTitle)),
    body: const MyAppBody(),
  );
}

The .build() method of your app's widgets can do ACSys.api(context) to get the object that implements the GraphQL client interface. See the documentation for the various GraphQL clients to see what's available.

Telemetry/Tracing (OpenTelemetry)

OpenTelemetry tracing is enabled by default (opt-out) for all apps using this package's entrypoints (runFermiApp, runFermiRouterApp).

• Traces are exported to the console by default (see ConsoleExporter).
  • In the future we will need a custom exporter for GraphQL. Good news is that otel is gRPC by default.
• You can override the exporter by calling initOpenTelemetry(exporter: ...) before app startup.
• Manual instrumentation is available for custom spans and events.

Manual Instrumentation Example

import 'package:flutter_controls_core/flutter_controls_core.dart';

final span = startSpan('operation', attributes: {'key': 'value'});
try {
  // ... your code ...
  addEvent(span, 'eventName', attributes: {'foo': 42});
} finally {
  endSpan(span);
}

Or use the convenience wrappers for automatic span management:

runWithSpan('operation', (span) {
  // ... your code ...
});

await runWithSpanAsync('asyncOp', (span) async {
  // ... your async code ...
});

Dependency Injection and Testing

Use the AppTracer interface and the appTracer instance for testable code:

class MyService {
  final AppTracer tracer;
  MyService(this.tracer);
  void doWork() {
    tracer.runWithSpan('work', (span) {
      // ...
    });
  }
}

In tests, inject a mock tracer if needed.

Opting Out

To disable tracing, you can override initOpenTelemetry with a no-op exporter or skip calling it (not recommended for most apps).

For more details, see the API documentation in lib/src/otel_tracing.dart.

TODO

• Add metrics
• Add logging