github.com/gdamore/mangos@v1.4.0/examples/pubsub/pubsub.go (about)

     1  // Copyright 2018 The Mangos Authors
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use file except in compliance with the License.
     5  // You may obtain a copy of the license at
     6  //
     7  //    http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  // pubsub implements a publish/subscribe example.  server is a listening
    16  // pub socket, and clients are dialing sub sockets.
    17  //
    18  // To use:
    19  //
    20  //   $ go build .
    21  //   $ url=tcp://127.0.0.1:40899
    22  //   $ ./pubsub server $url server & server=$! && sleep 1
    23  //   $ ./pubsub client $url client0 & client0=$!
    24  //   $ ./pubsub client $url client1 & client1=$!
    25  //   $ ./pubsub client $url client2 & client2=$!
    26  //   $ sleep 5
    27  //   $ kill $server $client0 $client1 $client2
    28  //
    29  package main
    30  
    31  import (
    32  	"fmt"
    33  	"os"
    34  	"time"
    35  
    36  	"nanomsg.org/go-mangos"
    37  	"nanomsg.org/go-mangos/protocol/pub"
    38  	"nanomsg.org/go-mangos/protocol/sub"
    39  	"nanomsg.org/go-mangos/transport/ipc"
    40  	"nanomsg.org/go-mangos/transport/tcp"
    41  )
    42  
    43  func die(format string, v ...interface{}) {
    44  	fmt.Fprintln(os.Stderr, fmt.Sprintf(format, v...))
    45  	os.Exit(1)
    46  }
    47  
    48  func date() string {
    49  	return time.Now().Format(time.ANSIC)
    50  }
    51  
    52  func server(url string) {
    53  	var sock mangos.Socket
    54  	var err error
    55  	if sock, err = pub.NewSocket(); err != nil {
    56  		die("can't get new pub socket: %s", err)
    57  	}
    58  	sock.AddTransport(ipc.NewTransport())
    59  	sock.AddTransport(tcp.NewTransport())
    60  	if err = sock.Listen(url); err != nil {
    61  		die("can't listen on pub socket: %s", err.Error())
    62  	}
    63  	for {
    64  		// Could also use sock.RecvMsg to get header
    65  		d := date()
    66  		fmt.Printf("SERVER: PUBLISHING DATE %s\n", d)
    67  		if err = sock.Send([]byte(d)); err != nil {
    68  			die("Failed publishing: %s", err.Error())
    69  		}
    70  		time.Sleep(time.Second)
    71  	}
    72  }
    73  
    74  func client(url string, name string) {
    75  	var sock mangos.Socket
    76  	var err error
    77  	var msg []byte
    78  
    79  	if sock, err = sub.NewSocket(); err != nil {
    80  		die("can't get new sub socket: %s", err.Error())
    81  	}
    82  	sock.AddTransport(ipc.NewTransport())
    83  	sock.AddTransport(tcp.NewTransport())
    84  	if err = sock.Dial(url); err != nil {
    85  		die("can't dial on sub socket: %s", err.Error())
    86  	}
    87  	// Empty byte array effectively subscribes to everything
    88  	err = sock.SetOption(mangos.OptionSubscribe, []byte(""))
    89  	if err != nil {
    90  		die("cannot subscribe: %s", err.Error())
    91  	}
    92  	for {
    93  		if msg, err = sock.Recv(); err != nil {
    94  			die("Cannot recv: %s", err.Error())
    95  		}
    96  		fmt.Printf("CLIENT(%s): RECEIVED %s\n", name, string(msg))
    97  	}
    98  }
    99  
   100  func main() {
   101  	if len(os.Args) > 2 && os.Args[1] == "server" {
   102  		server(os.Args[2])
   103  		os.Exit(0)
   104  	}
   105  	if len(os.Args) > 3 && os.Args[1] == "client" {
   106  		client(os.Args[2], os.Args[3])
   107  		os.Exit(0)
   108  	}
   109  	fmt.Fprintf(os.Stderr, "Usage: pubsub server|client <URL> <ARG>\n")
   110  	os.Exit(1)
   111  }