Native Android client for the Mezon messaging platform. The app is built in Kotlin with a Telegram-style UI layer: custom Canvas-based cells, a custom navigation stack, and Room for offline-first persistence. Architecture centers on controllers, NotificationCenter, and custom views (no Jetpack Compose for primary UI).
- Overview
- Requirements
- Getting started
- Protocol buffer setup
- Firebase configuration
- Build and test
- Updating
mezon-protocol - Architecture
- Repository layout
- Technology stack
- Performance notes
- Protocol and networking
| Area | Approach |
|---|---|
| UI | Custom View / ViewGroup cells (BaseCell), StaticLayout, shared paints from ThemeColors — optimized for list scrolling |
| State | @Singleton controllers hold in-memory caches (ArrayList, LongSparseArray); UI updates via NotificationCenter (not StateFlow for screens) |
| Persistence | Dual-write: update memory first, then async Room @Upsert on I/O dispatcher |
| Realtime | OkHttp WebSocket with protobuf Envelope; events fanned out in SocketEventDispatcher |
| Remote API | Ktor + OkHttp, protobuf request/response bodies |
| Tool | Notes |
|---|---|
| Android Studio | Current stable channel (e.g. Ladybug or newer) |
| JDK | 17+ (bundled with Android Studio is fine) |
| Android SDK | compileSdk 35, minSdk 24 (see app/build.gradle.kts) |
| Kotlin | 1.9.x (see gradle/libs.versions.toml) |
git clone <mezon-android-repository-url> ~/AndroidStudioProjects/mezonPlace the protocol repo anywhere on disk and keep the absolute path — the :core-proto module uses symlinks to it.
git clone https://github.com/mezonai/mezon-protocol.git ~/dev/mezon-protocolThe Gradle Protobuf plugin resolves imports using absolute symlink targets (do not use relative paths like ../../../).
cd ~/AndroidStudioProjects/mezon
mkdir -p core-proto/src/main/proto
PROTO_DIR="/absolute/path/to/mezon-protocol" # set to your actual clone
ln -sf "$PROTO_DIR/api" core-proto/src/main/proto/api
ln -sf "$PROTO_DIR/rtapi" core-proto/src/main/proto/rtapiExample:
ln -sf /Users/<you>/dev/mezon-protocol/api core-proto/src/main/proto/api
ln -sf /Users/<you>/dev/mezon-protocol/rtapi core-proto/src/main/proto/rtapiVerify:
ls -la core-proto/src/main/proto/
# api -> /absolute/path/to/mezon-protocol/api
# rtapi -> /absolute/path/to/mezon-protocol/rtapiOpen the mezon/ directory in Android Studio and let Gradle sync complete.
- Generated sources live in the
:core-protomodule. - Symlinks under
core-proto/src/main/proto/must point to theapi/andrtapi/trees insidemezon-protocol.
app/google-services.json is not committed. Obtain it from the Firebase project (e.g. mezon-772fa) or from your team, then place it at:
mezon/app/google-services.json
Copy mezon/mezon.secrets.properties.example to mezon/mezon.secrets.properties and fill in values (the real file is not committed; obtain from your team or internal secret store). Gradle fails early if this file is missing.
All commands are run from the mezon/ directory:
cd mezon
./gradlew assembleDebug
./gradlew installDebug
./gradlew assembleRelease
./gradlew testFor a full debug build including proto generation:
./gradlew assembleDebugWhen the protocol repository changes, pull and regenerate:
cd /path/to/mezon-protocol
git pull origin main
cd /path/to/mezon
./gradlew :core-proto:generateDebugProto
./gradlew app:compileDebugKotlinData flow (high level):
WebSocket ──► SocketEventDispatcher ──► Controller (cache + async Room)
REST ──► Controller ──► NotificationCenter.postOnMainThread
Room ──► Controller init / cold load ──► same caches + UI events
NotificationCenter ──► BaseFragment.observe() ──► adapters / cell.invalidate / partial row updates
| Layer | Responsibility |
|---|---|
| Controller | @Singleton services: synchronized in-memory models, REST and socket side effects, dual-write to Room, post NC events from init / API / socket |
| NotificationCenter | Main-thread event bus (integer event IDs); fragments register with BaseFragment.observe() |
| BaseFragment | Custom lifecycle (managed by ActionBarLayout, not AndroidX FragmentManager for the main stack) |
| Cells | BaseCell subclasses: onDraw(Canvas), update(mask), shared theme paints |
| Room | WAL, @Upsert, bounded list queries (e.g. message cap per channel) |
| SocketEventDispatcher | Demultiplexes Envelope into typed SharedFlows for controllers |
Single-activity: MainActivity. Screen stack and transitions use ActionBarLayout (custom ArrayList of BaseFragment, animated transitions, swipe-back). This is not the AndroidX Navigation Component graph.
| Event (examples) | Typical publisher | Typical subscriber |
|---|---|---|
dialogsNeedReload |
DialogsController / messages pipeline |
MessagesFragment |
messagesDidLoad / new/update/delete |
ChatController |
ChatFragment |
clansDidLoad / channels |
ClansController / ChannelController |
ClansFragment |
themeChanged / languageChanged |
ThemeManager / LocaleManager |
Fragments via rebuild or observers |
connectionStateChanged |
ConnectionController |
Shell / home |
sessionExpired |
AuthRepository |
MainActivity |
The canonical list and IDs live in NotificationCenter and related controllers.
app/src/main/java/com/mezon/mobile/
├── MainActivity.kt
├── MezonApplication.kt
├── auth/ # AuthRepository, LoginFragment
├── core/ # BaseFragment, ActionBarLayout, NotificationCenter, ThemeColors, BaseCell, …
├── data/db/ # MezonDatabase, DAOs, entities
├── di/ # Hilt modules, dispatchers
├── home/ # Controllers, MainTabsActivity, chat / messages / clans / profile / notifications
├── network/ # MezonApi, MezonSocket, SocketEventDispatcher, ApiCacheTracker
├── notification/ # FCM, local notifications, active channel
├── session/ # SessionManager, theme, locale
├── ui/cells/ # Reusable custom views (action bar, settings rows, …)
└── util/ # ContentParser, image helpers, …
A fuller map of types may exist in the parent workspace (e.g. CLAUDE.md at the monorepo root, if present).
| Area | Technology |
|---|---|
| Language | Kotlin 1.9.x |
| Build | Gradle with Kotlin DSL, KSP (Room, Hilt) — versions in gradle/libs.versions.toml |
| DI | Hilt |
| HTTP | Ktor + OkHttp |
| WebSocket | OkHttp, binary protobuf |
| DB | Room, WAL, @Upsert |
| Images | Custom MezonImageLoader (OkHttp, memory + disk cache) + ImageReceiver / AvatarDrawable |
| Session | DataStore Preferences |
| Push | Firebase Cloud Messaging (see BOM in version catalog) |
| Messages | Protobuf Lite (:core-proto) |
| Concurrency | Kotlin coroutines, @ApplicationScope / @IoDispatcher |
- Lists:
DiffUtilwhere appropriate;updateVisibleRows(mask)-style partial updates to avoid full adapter churn; scroll-state guards where implemented. - Controllers: in-memory update first, Room write off the main thread.
- Cold start: load bounded data from Room in controllers, then refresh from network.
- API:
ApiCacheTracker(TTL) to reduce duplicate REST work. - Canvas: avoid per-frame allocations in
onDraw; reuse layouts and paints per cell instance as documented in project guidelines.
| Artifact | Role |
|---|---|
api/api.proto |
REST messages (com.mezon.mezon.api) |
rtapi/realtime.proto |
WebSocket Envelope and realtime payloads (com.mezon.mezon.rtapi) |
- WebSocket (illustrative):
wss://<ws_url>/ws?token=<token>&status=true&platform=1&lang=en&format=protobuf - REST:
Content-Type: application/protowith bearer token (auth flows may use JSON + Basic as defined by the API).
Internal engineering documentation: keep setup steps in sync with gradle/libs.versions.toml and app/build.gradle.kts when versions change.