/
pubsub.go
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/
pubsub.go
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// Copyright 2018 The Mangos Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use file except in compliance with the License.
// You may obtain a copy of the license at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// pubsub implements a publish/subscribe example. server is a listening
// pub socket, and clients are dialing sub sockets.
//
// To use:
//
// $ go build .
// $ url=tcp://127.0.0.1:40899
// $ ./pubsub server $url server & server=$! && sleep 1
// $ ./pubsub client $url client0 & client0=$!
// $ ./pubsub client $url client1 & client1=$!
// $ ./pubsub client $url client2 & client2=$!
// $ sleep 5
// $ kill $server $client0 $client1 $client2
//
package main
import (
"fmt"
"os"
"time"
"nanomsg.org/go-mangos"
"nanomsg.org/go-mangos/protocol/pub"
"nanomsg.org/go-mangos/protocol/sub"
"nanomsg.org/go-mangos/transport/ipc"
"nanomsg.org/go-mangos/transport/tcp"
)
func die(format string, v ...interface{}) {
fmt.Fprintln(os.Stderr, fmt.Sprintf(format, v...))
os.Exit(1)
}
func date() string {
return time.Now().Format(time.ANSIC)
}
func server(url string) {
var sock mangos.Socket
var err error
if sock, err = pub.NewSocket(); err != nil {
die("can't get new pub socket: %s", err)
}
sock.AddTransport(ipc.NewTransport())
sock.AddTransport(tcp.NewTransport())
if err = sock.Listen(url); err != nil {
die("can't listen on pub socket: %s", err.Error())
}
for {
// Could also use sock.RecvMsg to get header
d := date()
fmt.Printf("SERVER: PUBLISHING DATE %s\n", d)
if err = sock.Send([]byte(d)); err != nil {
die("Failed publishing: %s", err.Error())
}
time.Sleep(time.Second)
}
}
func client(url string, name string) {
var sock mangos.Socket
var err error
var msg []byte
if sock, err = sub.NewSocket(); err != nil {
die("can't get new sub socket: %s", err.Error())
}
sock.AddTransport(ipc.NewTransport())
sock.AddTransport(tcp.NewTransport())
if err = sock.Dial(url); err != nil {
die("can't dial on sub socket: %s", err.Error())
}
// Empty byte array effectively subscribes to everything
err = sock.SetOption(mangos.OptionSubscribe, []byte(""))
if err != nil {
die("cannot subscribe: %s", err.Error())
}
for {
if msg, err = sock.Recv(); err != nil {
die("Cannot recv: %s", err.Error())
}
fmt.Printf("CLIENT(%s): RECEIVED %s\n", name, string(msg))
}
}
func main() {
if len(os.Args) > 2 && os.Args[1] == "server" {
server(os.Args[2])
os.Exit(0)
}
if len(os.Args) > 3 && os.Args[1] == "client" {
client(os.Args[2], os.Args[3])
os.Exit(0)
}
fmt.Fprintf(os.Stderr, "Usage: pubsub server|client <URL> <ARG>\n")
os.Exit(1)
}