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         "os"
  50         "time"
  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         tag     = "ackmain"
  61 )
  62
  63 // Connect to a STOMP broker, receive some messages, ACK them, and disconnect.
  64 func main() {
  65
  66         st := time.Now()
  67
  68         // Standard example connect sequence
  69         n, conn, e := sngecomm.CommonConnect(exampid, tag, ll)
  70         if e != nil {
  71                 ll.Fatalf("%stag:%s connsess:%s main_on_connect error:%v",
  72                         exampid, tag, sngecomm.Lcs,
  73                         e.Error()) // Handle this ......
  74         }
  75
  76         pbc := sngecomm.Pbc() // Print byte count
  77
  78         // *NOTE* your application functionaltiy goes here!
  79         // With Stomp, you must SUBSCRIBE to a destination in order to receive.
  80         // Subscribe returns a channel of MessageData struct.
  81         // Here we use a common utility routine to handle the differing subscribe
  82         // requirements of each protocol level.
  83         d := senv.Dest()
  84         id := stompngo.Uuid()
  85         sc := sngecomm.HandleSubscribe(conn, d, id, "client")
  86         ll.Printf("%stag:%s connsess:%s main_subscribe_complete\n",
  87                 exampid, tag, conn.Session())
  88         // Read data from the returned channel
  89         var md stompngo.MessageData
  90         for i := 1; i <= senv.Nmsgs(); i++ {
  91
  92                 select {
  93                 case md = <-sc:
  94                 case md = <-conn.MessageData:
  95                         // Frames RECEIPT or ERROR not expected here
  96                         ll.Fatalf("%stag:%s connsess:%s main_channel_frame error:%v",
  97                                 exampid, tag, conn.Session(),
  98                                 e.Error()) // Handle this ......
  99                 }
 100
 101                 ll.Printf("%stag:%s connsess:%s main_channel_read_complete\n",
 102                         exampid, tag, conn.Session())
 103                 // MessageData has two components:
 104                 // a) a Message struct
 105                 // b) an Error value.  Check the error value as usual
 106                 if md.Error != nil {
 107                         ll.Fatalf("%stag:%s connsess:%s main_channel_read error:%v",
 108                                 exampid, tag, conn.Session(),
 109                                 e.Error()) // Handle this ......
 110                 }
 111                 //
 112                 ll.Printf("%stag:%s connsess:%s frame_type:%v\n",
 113                         exampid, tag, conn.Session(),
 114                         md.Message.Command)
 115                 if md.Message.Command != stompngo.MESSAGE {
 116                         ll.Fatalf("%stag:%s connsess:%s bad_frame frame:%v",
 117                                 exampid, tag, conn.Session(),
 118                                 md.Message.Command) // Handle this ......
 119                 }
 120                 wh := md.Message.Headers
 121                 for j := 0; j < len(wh)-1; j += 2 {
 122                         ll.Printf("%stag:%s connsess:%s header:%s:%s\n",
 123                                 exampid, tag, conn.Session(),
 124                                 wh[j], wh[j+1])
 125                 }
 126                 if pbc > 0 {
 127                         maxlen := pbc
 128                         if len(md.Message.Body) < maxlen {
 129                                 maxlen = len(md.Message.Body)
 130                         }
 131                         ss := string(md.Message.Body[0:maxlen])
 132                         ll.Printf("%stag:%s connsess:%s message_payload body:%s\n",
 133                                 exampid, tag, conn.Session(),
 134                                 ss)
 135
 136                 }
 137                 // ACK the message just received.
 138                 // Agiain we use a utility routine to handle the different requirements
 139                 // of the protocol versions.
 140                 sngecomm.HandleAck(conn, md.Message.Headers, id)
 141                 ll.Printf("%stag:%s connsess:%s  ack_complete\n",
 142                         exampid, tag, conn.Session())
 143         }
 144         // It is polite to unsubscribe, although unnecessary if a disconnect follows.
 145         // Again we use a utility routine to handle the different protocol level
 146         // requirements.
 147         sngecomm.HandleUnsubscribe(conn, d, id)
 148         ll.Printf("%stag:%s connsess:%s stomp_unsubscribe_complete\n",
 149                 exampid, tag, conn.Session())
 150
 151         // Standard example disconnect sequence
 152         e = sngecomm.CommonDisconnect(n, conn, exampid, tag, ll)
 153         if e != nil {
 154                 ll.Fatalf("%stag:%s connsess:%s disconnect error:%v",
 155                         exampid, tag, conn.Session(),
 156                         e.Error()) // Handle this ......
 157         }
 158
 159         ll.Printf("%stag:%s connsess:%s main_elapsed:%v\n",
 160                 exampid, tag, conn.Session(),
 161                 time.Now().Sub(st))
 162
 163 }