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GlobalTV is a live-TV channel built with BrightScript and SceneGraph XML targeting Roku OS. The codebase follows the standard Roku channel layout and relies on three complementary patterns: a single shared global state node, task nodes for all network and background work, and SceneGraph’s observer mechanism for inter-component communication.

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Directory structure

GlobalTV_Roku/
├── manifest
├── Makefile
├── source/
│   ├── main.brs
│   ├── AppConstants.brs
│   ├── AppState.brs
│   └── utils/
│       ├── Logger.brs
│       ├── RegistryManager.brs
│       ├── ServerManager.brs
│       ├── HttpClient.brs
│       ├── HealthCheck.brs
│       └── NetworkDetector.brs
├── components/
│   ├── MainScene.xml
│   ├── MainScene.brs
│   ├── SplashScreen/
│   ├── OnboardingScreen/
│   ├── LoginScreen/
│   ├── MainScreen/
│   ├── PlayerScreen/
│   ├── SettingsScreen/
│   ├── tasks/
│   ├── ads/
│   └── overlays/
└── images/

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source/ vs components/

DirectoryPurpose
source/Pure BrightScript code that runs in the main thread: app entry point, global state initialisation, constants, and utility libraries (logging, registry, HTTP, server selection).
components/SceneGraph components — each sub-folder contains an .xml interface declaration and a .brs behaviour file. Components run in their own render-thread scope. Task nodes under components/tasks/ execute on background threads.

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Component hierarchy

The SceneGraph tree at runtime looks like this: 
roSGScreen
└── MainScene  (extends Scene)
    ├── bgRect  (Rectangle — full-screen background)
    ├── [loading Label]          ← transient, shown during async work
    ├── SplashScreen             ← shown on cold start
    ├── OnboardingScreen         ← shown when no saved credentials
    ├── LoginScreen              ← username / password entry
    ├── MainScreen               ← channel grid / overlay
    ├── PlayerScreen             ← live video + ad layer
    ├── SettingsScreen           ← server & safe-area config
    ├── OfflineDialog            ← network error
    ├── UserInactiveDialog       ← session-expired prompt
    ├── ConfirmExitDialog        ← back-button exit confirmation
    └── [Task nodes]             ← HandshakeTask, AuthTask,
                                    PlaylistTask, AdsPollingTask,
                                    ConnectivityTask, SessionAuthTask
At most one “screen” is active at a time. MainScreen and PlayerScreen are kept alive simultaneously once the user reaches the home state so that the channel overlay can be toggled without re-creating either node.

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Key design patterns

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Global state via m.global

All shared runtime state lives in a single roSGNode accessible to every component as m.global. The node is initialised once by MainScene.init() calling GTV_InitGlobalState() from source/AppState.brs. Components read fields directly and write through the node to trigger observers elsewhere. 
' source/AppState.brs
sub GTV_InitGlobalState()
    m.global.addFields({
        activeServer     : "",
        isAuthenticated  : false,
        channelList      : [],
        playerState      : "stopped",
        ' ... (see Global state reference)
    })
end sub

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Task-based async work

All network I/O is performed in dedicated Task nodes so the render thread never blocks. MainScene creates each task node, sets its input fields, sets control = "RUN", and observes its done field to receive the result. 
' components/MainScene.brs
m.authTask          = CreateObject("roSGNode", "AuthTask")
m.authTask.username = username
m.authTask.password = password
m.authTask.observeField("done", "OnAuthDone")
m.authTask.control  = "RUN"

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Observer pattern

SceneGraph field observers wire components together without direct references. A child component exposes an output field; the parent observes it and reacts in a callback. 
' MainScene listening to SplashScreen
splash.observeField("splashDone", "OnSplashDone")

' MainScene listening to deep-link fields on itself
m.top.observeField("currentDesignResolution", "OnSceneResolutionChanged")

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Periodic timers

Background polling (session auth check, ads, connectivity) uses roSGNode Timer instances attached as children of MainScene. Timer durations and intervals come from constants in AppConstants(). 
m.sessionAuthTimer          = CreateObject("roSGNode", "Timer")
m.sessionAuthTimer.duration = Int(c.SESSION_AUTH_CHECK_MS / 1000)  ' default 420 s
m.sessionAuthTimer.repeat   = true
m.sessionAuthTimer.observeField("fire", "OnSessionAuthTimer")

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Technology stack

BrightScript

Roku’s scripting language. Used for all logic in both source/ and components/ .brs files.

SceneGraph XML

Declarative component definitions (.xml). Describe the component interface, script includes, and initial child nodes.

Roku OS

Target platform. The channel runs inside a sandboxed roSGScreen created in source/main.brs.

Makefile

Build tooling: make zip packages the channel, make install sideloads it to a device via the Roku Developer Application Installer.
The manifest file declares the channel version, splash screens, supported resolutions, and supports_input_launch=1 (required for deep-link input events).

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