asyncmachine.dev

asyncmachine-go support WebAssembly through WebSockets-to-TCP tunnels and MessageChannels between WebWorkers for all packages besides /pkg/pubsub and /pkg/node (not due to technical reasons). The distributed nature of the framework makes a perfect fit for a single-threaded environment of WASM, which can easily synchronize and chunk work between CPU cores.

Extensive information about WASM for asyncmachine can be found at:

Building WASM is as simple as:

env GOOS=js GOARCH=wasm go build -o main.wasm ./cmd

Code Differences

Network constructs require additional options for WASM, although sane defaults are mostly in place.

aRPC Server

srv, err := arpc.NewServer(ctx, addrRelay, mach.Id(), mach, &arpc.ServerOpts{
    // eg localhost:8080/listen/bar/localhost:7070 opens 7070 for "bar"
    WebSocketTunnel: arpc.WsListenPath(mach.Id(), addrListen),
})

aRPC Client

client, err := arpc.NewClient(ctx, addrRelay, fooHandlerMach.Id(), states.FooSchema, &arpc.ClientOpts{
    // eg localhost:8080/dial/bar/localhost:7070 dials 7070 for "bar"
    WebSocket: arpc.WsDialPath(mach.Id(), addrDial),
})

REPL

repl, err := arpc.MachReplWs(mach, addrRelay, &arpc.ReplOpts{
    // eg localhost:8080/listen/bar/localhost:7070 opens 7070 for "bar"
    WebSocketTunnel: arpc.WsListenPath("repl-"+mach.Id(), addrListen),
})

Debugging

The delve debugger doesn’t support the WASM target yet, but there are tools that can help today:

am-dbg
OpenTelemetry from /pkg/telemetry
browser’s profiler
runtime/trace
go test with mocked handlers

Known Issues

stock HTTP Otel expoter is broken in WASM and needs a replace directive (source)

replace go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp => github.com/pancsta/opentelemetry-go/exporters/otlp/otlptrace/otlptracehttp v0.0.0-20260331193851-f087fcb1fc48