Files
nats.go/examples/nats-pub/main.go

88 lines
2.0 KiB
Go

// Copyright 2012-2019 The NATS Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this 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.
package main
import (
"flag"
"log"
"os"
"github.com/nats-io/nats.go"
)
// NOTE: Can test with demo servers.
// nats-pub -s demo.nats.io <subject> <msg>
// nats-pub -s demo.nats.io:4443 <subject> <msg> (TLS version)
func usage() {
log.Printf("Usage: nats-pub [-s server] [-creds file] <subject> <msg>\n")
flag.PrintDefaults()
}
func showUsageAndExit(exitcode int) {
usage()
os.Exit(exitcode)
}
func main() {
var urls = flag.String("s", nats.DefaultURL, "The nats server URLs (separated by comma)")
var userCreds = flag.String("creds", "", "User Credentials File")
var showHelp = flag.Bool("h", false, "Show help message")
var reply = flag.String("reply", "", "Sets a specific reply subject")
log.SetFlags(0)
flag.Usage = usage
flag.Parse()
if *showHelp {
showUsageAndExit(0)
}
args := flag.Args()
if len(args) != 2 {
showUsageAndExit(1)
}
// Connect Options.
opts := []nats.Option{nats.Name("NATS Sample Publisher")}
// Use UserCredentials
if *userCreds != "" {
opts = append(opts, nats.UserCredentials(*userCreds))
}
// Connect to NATS
nc, err := nats.Connect(*urls, opts...)
if err != nil {
log.Fatal(err)
}
defer nc.Close()
subj, msg := args[0], []byte(args[1])
if reply != nil && *reply != "" {
nc.PublishRequest(subj, *reply, msg)
} else {
nc.Publish(subj, msg)
}
nc.Flush()
if err := nc.LastError(); err != nil {
log.Fatal(err)
} else {
log.Printf("Published [%s] : '%s'\n", subj, msg)
}
}