tauri-impl-design-patterns

tauri-impl-design-patterns

IPC Decision Tree: Commands vs Events vs Channels

Choose the right IPC mechanism based on data flow pattern:

What is the communication pattern?
|
+-- Request/Response (frontend asks, Rust answers)
|   --> Use COMMANDS (invoke)
|   Examples: load file, save data, compute result, CRUD operations
|
+-- Push Notification (Rust notifies frontend, or frontend broadcasts)
|   --> Use EVENTS (emit/listen)
|   Examples: background task done, settings changed, new data available
|
+-- Streaming Data (continuous flow from Rust to frontend)
|   --> Use CHANNELS (Channel<T>)
|   Examples: download progress, log streaming, live sensor data
|
+-- Bidirectional Real-Time
    --> Use EVENTS for both directions
    Examples: chat messages, collaborative editing, sync status

IPC Mechanism Comparison

Feature	Commands	Events	Channels
Direction	Frontend -> Rust -> Frontend	Bidirectional	Rust -> Frontend
Cardinality	1 request : 1 response	1 emit : N listeners	1 command : N messages
Lifetime	Single invocation	App lifetime	Tied to command call
Targeting	Specific command	Broadcast or filtered	Specific caller
Error handling	Result<T, E>	Fire-and-forget	Send errors possible
Typing	Strong (generics)	Payload-based	Strong (generics)
Use when	CRUD, queries, actions	Notifications, state sync	Progress, streaming

When to Combine

Pattern: Command + Channel
Use: Long-running operations with progress
Example: File download -- invoke starts it, channel streams progress

Pattern: Command + Event
Use: Action triggers background work, result broadcast later
Example: Start scan -> emit "scan-complete" when done

Pattern: Event + Event
Use: Multi-window state synchronization
Example: Window A emits "data-changed", Window B listens and refreshes

---

State Architecture

Where to Put State

+--------------------------------------------------+
|                STATE DECISION MATRIX               |
+------------------+----------------+---------------+
| Data Type        | Put In Rust    | Put In JS     |
+------------------+----------------+---------------+
| Persistent data  | YES            | Cache only    |
| User settings    | YES (Store)    | Mirror/cache  |
| Auth tokens      | YES (secure)   | Never store   |
| Database conn    | YES            | Never         |
| UI state         | No             | YES           |
| Form values      | No             | YES           |
| Animation state  | No             | YES           |
| Ephemeral flags  | No             | YES           |
| Shared/multi-win | YES            | Per-window    |
| Heavy compute    | YES (result)   | Display only  |
+------------------+----------------+---------------+