Implement v2 Protocol. Adding expectedVersion for optimistic concurrency and metadata.

server/zeromq.go

@@ -0,0 +1,175 @@
+package server
+
+import (
+	"fmt"
+	data "../data"
+	actions "../actions"
+	"github.com/satori/go.uuid"
+	"github.com/pebbe/zmq4"
+	"encoding/binary"
+)
+
+var context *zmq4.Context
+var replySocket *zmq4.Socket
+
+func Bind(addr string) {
+	var err error;
+
+	context, err = zmq4.NewContext()
+	if err != nil {
+		panic(err)
+	}
+
+	replySocket, err = context.NewSocket(zmq4.REP)
+	if err != nil {
+		panic(err)
+	}
+
+	err = replySocket.Bind(addr)
+	if err != nil {
+		panic(err)
+	}
+}
+
+func Destroy() {
+	replySocket.Close()
+	context.Term()
+}
+
+const NO_FLAGS = zmq4.Flag(0)
+const UUID_SIZE = 16
+const COMMAND_FRAME = 0
+const ARGS_FRAME = 1
+const PAYLOAD_FRAME = 2
+const METADATA_FRAME = 3
+
+func Listen(handler actions.Handler) {
+	for {
+		message, err := replySocket.RecvMessageBytes(NO_FLAGS)
+		if err != nil {
+			fmt.Println("Error receiving command from client", err)
+			continue
+		}
+
+		command := string(message[COMMAND_FRAME])
+		switch command {
+		case "AddEvent":
+			// v1 - "AddEvent" [AggregateId] {payload}
+			aggregateId, err := uuid.FromBytes(message[ARGS_FRAME])
+			if err != nil {
+				fmt.Println("Wrong format for AggregateId", err)
+				break
+			}
+			fmt.Println("->", command, aggregateId.String())
+			payload := message[PAYLOAD_FRAME]
+			err = handler.AddEvent(data.Event{AggregateId: aggregateId, Payload: payload, Metadata: nil}, actions.NO_EXPECTEDVERSION)
+			if err != nil {
+				replySocket.Send(fmt.Sprintf("Error: %v", err), NO_FLAGS)
+				fmt.Println(err)
+				break
+			}
+			replySocket.Send("Ok", NO_FLAGS)
+		case "AddEvent_v2":
+			// v2 - "AddEvent" 16:AggregateId,4:expectedVersion {payload} {metadata}
+			aggregateId, err := uuid.FromBytes(message[ARGS_FRAME][0:UUID_SIZE])
+			if err != nil {
+				fmt.Println("Wrong format for AggregateId", err)
+				break
+			}
+			expectedVersion := binary.LittleEndian.Uint32(message[ARGS_FRAME][UUID_SIZE:])
+			fmt.Println("->", command, aggregateId.String(), expectedVersion)
+			payload := message[PAYLOAD_FRAME]
+			metadata := message[METADATA_FRAME]
+			err = handler.AddEvent(data.Event{AggregateId: aggregateId, Payload: payload, Metadata: metadata}, expectedVersion)
+			if err != nil {
+				replySocket.Send(fmt.Sprintf("Error: %v", err), NO_FLAGS)
+				fmt.Println(err)
+				break
+			}
+			replySocket.Send("Ok", NO_FLAGS)
+		case "ReadStream", "ReadStream_v2":
+			aggregateId, err := uuid.FromBytes(message[ARGS_FRAME])
+			if err != nil {
+				fmt.Println("Wrong format for AggregateId", err)
+				break
+			}
+			fmt.Println("->", command, aggregateId.String())
+			events, err := handler.RetrieveFor(aggregateId)
+			if err != nil {
+				replySocket.Send(fmt.Sprintf("Error: %v", err), NO_FLAGS)
+				fmt.Println(err)
+				break
+			}
+			if command == "ReadStream_v2" {
+				sendEvents_v2(replySocket, events)
+				break;
+			}
+			sendEvents_v1(replySocket, events)
+		case "ReadAll", "ReadAll_v2":
+			fmt.Println("->", command)
+			events, err := handler.RetrieveAll()
+			if err != nil {
+				replySocket.Send(fmt.Sprintf("Error: %v", err), NO_FLAGS)
+				fmt.Println(err)
+				break
+			}
+			if command == "ReadAll_v2" {
+				sendEvents_v2(replySocket, events)
+				break;
+			}
+			sendEvents_v1(replySocket, events)
+		case "Shutdown":
+			fmt.Println("->", command)
+			return
+		}
+	}
+}
+
+func sendEvent_v1(socket *zmq4.Socket, event *data.Event, isLast bool) {
+	lastFlag := zmq4.SNDMORE
+	if (isLast) {
+		lastFlag = NO_FLAGS
+	}
+	socket.SendBytes(event.Payload.([]byte), lastFlag)
+}
+
+func sendEvents_v1(socket *zmq4.Socket, events []*data.Event) {
+	len := len(events)
+	if (len == 0) {
+		socket.Send("0", NO_FLAGS)
+		return
+	}
+
+	socket.Send(fmt.Sprintf("%v", len), zmq4.SNDMORE)
+
+	i := 0
+	for ; i < len; i++ {
+		sendEvent_v1(socket, events[i], i == len - 1)
+	}
+	fmt.Println("<-", len, "events")
+}
+
+func sendEvent_v2(socket *zmq4.Socket, event *data.Event, isLast bool) {
+	socket.SendBytes(event.Payload.([]byte), zmq4.SNDMORE)
+	lastFlag := zmq4.SNDMORE
+	if (isLast) {
+		lastFlag = NO_FLAGS
+	}
+	socket.SendBytes(event.Metadata.([]byte), lastFlag)
+}
+
+func sendEvents_v2(socket *zmq4.Socket, events []*data.Event) {
+	len := len(events)
+	if (len == 0) {
+		socket.Send("0", NO_FLAGS)
+		return
+	}
+
+	socket.Send(fmt.Sprintf("%v", len), zmq4.SNDMORE)
+
+	i := 0
+	for ; i < len; i++ {
+		sendEvent_v2(socket, events[i], i == len - 1)
+	}
+	fmt.Println("<-", len, "events")
+}