#moonrpc

Moved on mooncakes from Lfan-ke/moonrpc to moonbitstack/moonrpc.

let server = @net.GrpcServer::new()

// unary: one request, one reply.
server.register("/greet.Greeter/SayHello", req => handle(req))

// server-streaming: one request, an ordered run of replies.
server.register_server_streaming("/count.C/Up", (ctx, req) => [
  first(req), second(req), third(req),
])

// client-streaming: many requests collected, one reply at half-close.
server.register_client_streaming("/sum.S/Add", (ctx, msgs) => fold(msgs))

// bidi: each request echoed as it arrives, a farewell at half-close.
server.register_bidi("/chat.C/Echo", ctx => @moonrpc.BidiHandler::{
  on_message: m => [reply_to(m)],
  on_end: () => [b"bye"],
})

server.serve(port=50051)   // a real gRPC / in-process client gets the replies

#The Channel client

let chan = @net.Channel::connect("127.0.0.1", 50051)

// unary.
let reply = chan.unary("/greet.Greeter/SayHello", request)
reply.messages[0]   // the reply message; reply.grpc_status is 0 on success

// server-streaming: one request, every framed reply reassembled in order.
let out = chan.server_streaming("/count.C/Up", request)   // out.messages

// client-streaming: many requests, one reply.
let sum = chan.client_streaming("/sum.S/Add", [a, b, c])

// a deadline: sent as grpc-timeout and enforced locally — if it elapses the
// stream is reset and grpc_status comes back DEADLINE_EXCEEDED (4).
let bounded = chan.unary("/slow.S/Wait", request, timeout_millis=Some(200))

#Health and interceptors

let health = @moonrpc.HealthService::new()
health.set_status("greet.Greeter", @moonrpc.Serving)
server.register_health(health)      // Check + Watch on /grpc.health.v1.Health/*

engine.add_unary_interceptor((ctx, req, next) => {
  // inspect, then proceed — or return without calling next to short-circuit.
  next(ctx, req)
})

#Protobuf and Server Reflection

let w = @moonrpc.PbWriter::new()
w.string_(1, "testing")          // field 1, a length-delimited string
w.int32(2, -1)                   // field 2, a varint (negative -> ten octets)
let r = @moonrpc.PbReader::new(w.to_bytes())
let (field, wire) = r.read_tag() // (1, LengthDelim)
r.read_string()                  // "testing"

let greeter : @moonrpc.ServiceDescriptor = {
  name: "Greeter",
  methods: [
    { name: "SayHello", input_type: ".greet.HelloRequest",
      output_type: ".greet.HelloReply",
      client_streaming: false, server_streaming: false },
  ],
}
let refl = @moonrpc.ReflectionService::new()
refl.add_file(@moonrpc.FileDescriptor::new("greet.proto", "greet", services=[greeter]))
server.register_reflection(refl)   // a reflection client now lists + describes greet.Greeter

let engine = @moonrpc.H2Server::new()
engine.register("/echo.Echo/Say", req => req)
let out = engine.feed(frame)   // -> [HEADERS(:status 200), DATA(reply), HEADERS(grpc-status:0)]

#The gRPC message framing

let frame = @moonrpc.encode_message(b"hello grpc")
// [0x00][0x00 0x00 0x00 0x0A]["hello grpc"]  — 1-byte flag + 4-byte big-endian length + payload

let (compressed, payload) = @moonrpc.decode_message(frame).unwrap()
// (false, b"hello grpc")

#The HTTP/2 frame layer (RFC 7540)

let f = @moonrpc.Frame::Headers(
  stream_id=1, fragment=block, end_stream=true, end_headers=true,
  priority=None, padding=0,
)
let bytes = f.encode()                       // 9-octet header + payload
let (frame, consumed) = @moonrpc.decode_frame(bytes)   // raises Incomplete until whole

@moonrpc.has_connection_preface(buf)         // PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n (§3.5)

let s = @moonrpc.Stream::new(1)
s.send(@moonrpc.StreamEvent::Headers(end_stream=false))  // -> Open
s.recv(@moonrpc.StreamEvent::Data(end_stream=true))      // -> HalfClosedRemote

#Complete HPACK (RFC 7541)

let enc = @moonrpc.HpackEncoder::new(huffman=true)
let block = enc.encode([{ name: b":method", value: b"GET" },
                        { name: b":authority", value: b"www.example.com" }])

let dec = @moonrpc.HpackDecoder::new()
let headers = dec.decode(block)              // back to the same header list

@moonrpc.huffman_encode(b"www.example.com")  // f1e3 c2e5 f23a 6ba0 ab90 f4ff — §C.4.1

#The status model

@moonrpc.Status::code(NotFound)          // 5
@moonrpc.Status::name(Unauthenticated)   // "UNAUTHENTICATED"   (all 17 canonical grpc-status codes)

let m : @moonrpc.Method = { service: "greet.Greeter", name: "SayHello" }
m.path()                                 // "/greet.Greeter/SayHello"

#Roadmap (the self-built stack, sequenced to completeness)

#License