60009124c9
Some checks failed
CI / Build and Test (push) Has been cancelled
Streams listed in Options.Streams are created by Start() when the embedded NATS server initializes, replacing manual EnsureStream calls during setup. Migrates nats-chatroom and pubsub-crud examples.
80 lines
3.3 KiB
Markdown
80 lines
3.3 KiB
Markdown
# NATS Chatroom Example (Embedded)
|
|
|
|
A chatroom built with Via and an **embedded NATS server**, demonstrating pub/sub messaging as an alternative to the custom `Rooms` implementation in `../chatroom`.
|
|
|
|
Via includes an embedded NATS server that starts automatically — no external server required.
|
|
|
|
## Key Differences from Original Chatroom
|
|
|
|
| Aspect | Original (`../chatroom`) | This Example |
|
|
|--------|-------------------------|--------------|
|
|
| Pub/sub | Custom `Rooms` struct (~160 lines) | NATS subjects |
|
|
| Member tracking | Manual `map[TU]Syncable` | NATS handles subscribers |
|
|
| Publish timing | Ticker every 100ms + dirty flag | Instant delivery |
|
|
| Durability | None (in-memory) | JetStream persists to disk |
|
|
| Multi-instance | Not supported | Works across server instances |
|
|
| External deps | None | **None** (NATS embedded in binary) |
|
|
|
|
## Run the Example
|
|
|
|
```bash
|
|
go run ./internal/examples/nats-chatroom
|
|
```
|
|
|
|
That's it. No separate NATS server needed.
|
|
|
|
Open multiple browser tabs at http://localhost:7331 to see messages broadcast across all clients.
|
|
|
|
## Architecture
|
|
|
|
```
|
|
┌─────────────────────────────────────────────────────────┐
|
|
│ Single Binary │
|
|
│ │
|
|
│ Browser A Embedded NATS Browser B │
|
|
│ │ │ │ │
|
|
│ │-- Via Action ---> │ │ │
|
|
│ │ (Send msg) │ │ │
|
|
│ │ │ │ │
|
|
│ │ nc.Publish() │ │
|
|
│ │ "chat.room.Go" │ │
|
|
│ │ │ │ │
|
|
│ │<-- Subscribe -----|---- Subscribe --->│ │
|
|
│ │ callback │ callback │ │
|
|
│ │ │ │ │
|
|
│ │-- c.Sync() ------>│<--- c.Sync() -----| │
|
|
│ │ (SSE) │ (SSE) │ │
|
|
│ │
|
|
└─────────────────────────────────────────────────────────┘
|
|
```
|
|
|
|
## JetStream Durability
|
|
|
|
Messages persist to disk via JetStream. Streams are declared in `Options.Streams` and created automatically when `v.Start()` initializes the embedded NATS server:
|
|
|
|
```go
|
|
v.Config(via.Options{
|
|
Streams: []via.StreamConfig{{
|
|
Name: "CHAT",
|
|
Subjects: []string{"chat.>"},
|
|
MaxMsgs: 1000,
|
|
MaxAge: 24 * time.Hour,
|
|
}},
|
|
})
|
|
```
|
|
|
|
Stop and restart the app - chat history survives.
|
|
|
|
## Code Comparison
|
|
|
|
**Original chatroom - 160+ lines of custom pub/sub:**
|
|
- `Rooms` struct with named rooms
|
|
- `Room` with member tracking, mutex, dirty flag
|
|
- Ticker-based publish loop
|
|
- Manual join/leave channels
|
|
|
|
**This example - ~60 lines of NATS integration:**
|
|
- `via.Subscribe(c, subject, handler)` for receiving
|
|
- `via.Publish(c, subject, data)` for sending
|
|
- Streams declared in `Options` — NATS handles delivery, no polling
|