ack/ack.go

   1 //
   2 // Copyright © 2011-2016 Guy M. Allard
   3 //
   4 // Licensed under the Apache License, Version 2.0 (the "License");
   5 // you may not use this file except in compliance with the License.
   6 // You may obtain a copy of the License at
   7 //
   8 //     http://www.apache.org/licenses/LICENSE-2.0
   9 //
  10 // Unless required by applicable law or agreed to in writing, software
  11 // distributed under the License is distributed on an "AS IS" BASIS,
  12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13 // See the License for the specific language governing permissions and
  14 // limitations under the License.
  15 //
  16
  17 /*
  18 Receive messages from a STOMP broker, and ACK them.
  19
  20         Examples:
  21
  22                 # ACK messages from a broker with all defaults:
  23                 # Host is "localhost"
  24                 # Port is 61613
  25                 # Login is "guest"
  26                 # Passcode is "guest
  27                 # Virtual Host is "localhost"
  28                 # Protocol is 1.2
  29                 go run ack.go
  30
  31                 # ACK messages from a broker using STOMP protocol level 1.0:
  32                 STOMP_PROTOCOL=1.0 go run ack.go
  33
  34                 # ACK messages from a broker using a custom host and port:
  35                 STOMP_HOST=tjjackson STOMP_PORT=62613 go run ack.go
  36
  37                 # ACK messages from a broker using a custom port and virtual host:
  38                 STOMP_PORT=41613 STOMP_VHOST="/" go run ack.go
  39
  40                 # ACK messages from a broker using a custom login and passcode:
  41                 STOMP_LOGIN="userid" STOMP_PASSCODE="t0ps3cr3t" go run ack.go
  42
  43 */
  44 package main
  45
  46 import (
  47         "github.com/gmallard/stompngo"
  48         "log"
  49         "net"
  50         "os"
  51         // senv methods could be used in general by stompngo clients.
  52         "github.com/gmallard/stompngo/senv"
  53         // sngecomm methods are used specifically for these example clients.
  54         "github.com/gmallard/stompngo_examples/sngecomm"
  55 )
  56
  57 var (
  58         exampid = "ack: "
  59         ll      = log.New(os.Stdout, "EACK ", log.Ldate|log.Lmicroseconds|log.Lshortfile)
  60 )
  61
  62 // Connect to a STOMP broker, receive some messages, ACK them, and disconnect.
  63 func main() {
  64         ll.Printf("%s v1:%v\n", exampid, "starts_...")
  65
  66         // Set up the connection.
  67         h, p := senv.HostAndPort()
  68         hap := net.JoinHostPort(h, p)
  69         n, e := net.Dial("tcp", hap)
  70         if e != nil {
  71                 ll.Fatalf("%s %s\n", exampid, e.Error()) // Handle this ......
  72         }
  73         ll.Printf("%s v1:%v v2:%v\n", exampid, "dial complete ...", hap)
  74         ch := sngecomm.ConnectHeaders()
  75         conn, e := stompngo.Connect(n, ch)
  76         if e != nil {
  77                 ll.Fatalf("%s %s\n", exampid, e.Error()) // Handle this ......
  78         }
  79         ll.Printf("%s v1:%v v2:%v\n", exampid, "stomp connect complete ...", conn.Protocol())
  80
  81         pbc := sngecomm.Pbc() // Print byte count
  82
  83         // *NOTE* your application functionaltiy goes here!
  84         // With Stomp, you must SUBSCRIBE to a destination in order to receive.
  85         // Subscribe returns a channel of MessageData struct.
  86         // Here we use a common utility routine to handle the differing subscribe
  87         // requirements of each protocol level.
  88         d := senv.Dest()
  89         id := stompngo.Uuid()
  90         sc := sngecomm.HandleSubscribe(conn, d, id, "client")
  91         ll.Printf("%s v1:%v\n", exampid, "stomp_subscribe_complete_...")
  92         // Read data from the returned channel
  93         var md stompngo.MessageData
  94         for i := 1; i <= senv.Nmsgs(); i++ {
  95
  96                 select {
  97                 case md = <-sc:
  98                 case md = <-conn.MessageData:
  99                         // Frames RECEIPT or ERROR not expected here
 100                         ll.Fatalf("%s v1:%v\n", exampid, md) // Handle this
 101                 }
 102
 103                 ll.Printf("%s v1:%v\n", exampid, "channel_read_complete_...")
 104                 // MessageData has two components:
 105                 // a) a Message struct
 106                 // b) an Error value.  Check the error value as usual
 107                 if md.Error != nil {
 108                         ll.Fatalf("%s  f4v:%v\n", exampid, md.Error) // Handle this
 109                 }
 110                 //
 111                 ll.Printf("Frame Type: %s\n", md.Message.Command) // Will be MESSAGE or ERROR!
 112                 if md.Message.Command != stompngo.MESSAGE {
 113                         ll.Fatalf("%s  f4v:%v\n", exampid, md) // Handle this ...
 114                 }
 115                 wh := md.Message.Headers
 116                 for j := 0; j < len(wh)-1; j += 2 {
 117                         ll.Printf("Header: %s:%s\n", wh[j], wh[j+1])
 118                 }
 119                 if pbc > 0 {
 120                         maxlen := pbc
 121                         if len(md.Message.Body) < maxlen {
 122                                 maxlen = len(md.Message.Body)
 123                         }
 124                         ss := string(md.Message.Body[0:maxlen])
 125                         ll.Printf("Payload: %s\n", ss) // Data payload
 126                 }
 127                 // ACK the message just received.
 128                 // Agiain we use a utility routine to handle the different requirements
 129                 // of the protocol versions.
 130                 sngecomm.HandleAck(conn, md.Message.Headers, id)
 131                 ll.Printf("%s v1:%v\n", exampid, "ACK_complete_...")
 132         }
 133         // It is polite to unsubscribe, although unnecessary if a disconnect follows.
 134         // Again we use a utility routine to handle the different protocol level
 135         // requirements.
 136         sngecomm.HandleUnsubscribe(conn, d, id)
 137         ll.Printf("%s v1:%v\n", exampid, "stomp_unsubscribe_complete_...")
 138
 139         // Disconnect from the Stomp server
 140         e = conn.Disconnect(stompngo.Headers{})
 141         if e != nil {
 142                 ll.Fatalf("%s %s\n", exampid, e.Error()) // Handle this ......
 143         }
 144         ll.Printf("%s v1:%v\n", exampid, "stomp_disconnect_complete_...")
 145         // Close the network connection
 146         e = n.Close()
 147         if e != nil {
 148                 ll.Fatalf("%s %s\n", exampid, e.Error()) // Handle this ......
 149         }
 150         ll.Printf("%s v1:%v\n", exampid, "network_close_complete_...")
 151
 152         ll.Printf("%s v1:%v\n", exampid, "ends_...")
 153 }