ack/ack.go

   1 //
   2 // Copyright © 2011-2013 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 1.1
  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         "fmt"
  48         "github.com/gmallard/stompngo"
  49         "github.com/gmallard/stompngo_examples/sngecomm"
  50         "log"
  51         "net"
  52 )
  53
  54 var exampid = "ack: "
  55
  56 // Connect to a STOMP broker, receive some messages, ACK them, and disconnect.
  57 func main() {
  58         fmt.Println(exampid + "starts ...")
  59
  60         // Set up the connection.
  61         h, p := sngecomm.HostAndPort()
  62         n, e := net.Dial("tcp", net.JoinHostPort(h, p))
  63         if e != nil {
  64                 log.Fatalln(e) // Handle this ......
  65         }
  66         fmt.Println(exampid + "dial complete ...")
  67         ch := sngecomm.ConnectHeaders()
  68         conn, e := stompngo.Connect(n, ch)
  69         if e != nil {
  70                 log.Fatalln(e) // Handle this ......
  71         }
  72         fmt.Println(exampid+"stomp connect complete ...", conn.Protocol())
  73
  74         // *NOTE* your application functionaltiy goes here!
  75         // With Stomp, you must SUBSCRIBE to a destination in order to receive.
  76         // Subscribe returns a channel of MessageData struct.
  77         // Here we use a common utility routine to handle the differing subscribe
  78         // requirements of each protocol level.
  79         d := sngecomm.Dest()
  80         id := stompngo.Uuid()
  81         r := sngecomm.Subscribe(conn, d, id, "client")
  82         fmt.Println(exampid + "stomp subscribe complete ...")
  83         // Read data from the returned channel
  84         for i := 1; i <= sngecomm.Nmsgs(); i++ {
  85                 m := <-r
  86                 fmt.Println(exampid + "channel read complete ...")
  87                 // MessageData has two components:
  88                 // a) a Message struct
  89                 // b) an Error value.  Check the error value as usual
  90                 if m.Error != nil {
  91                         log.Fatalln(m.Error) // Handle this
  92                 }
  93                 //
  94                 fmt.Printf("Frame Type: %s\n", m.Message.Command) // Will be MESSAGE or ERROR!
  95                 if m.Message.Command != stompngo.MESSAGE {
  96                         log.Fatalln(m) // Handle this ...
  97                 }
  98                 h := m.Message.Headers
  99                 for j := 0; j < len(h)-1; j += 2 {
 100                         fmt.Printf("Header: %s:%s\n", h[j], h[j+1])
 101                 }
 102                 fmt.Printf("Payload: %s\n", string(m.Message.Body)) // Data payload
 103                 // ACK the message just received.
 104                 // Agiain we use a utility routine to handle the different requirements
 105                 // of the protocol versions.
 106                 sngecomm.Ack(conn, m.Message.Headers, id)
 107                 fmt.Println(exampid + "ACK complete ...")
 108         }
 109         // It is polite to unsubscribe, although unnecessary if a disconnect follows.
 110         // Again we use a utility routine to handle the different protocol level
 111         // requirements.
 112         sngecomm.Unsubscribe(conn, d, id)
 113         fmt.Println(exampid + "stomp unsubscribe complete ...")
 114
 115         // Disconnect from the Stomp server
 116         e = conn.Disconnect(stompngo.Headers{})
 117         if e != nil {
 118                 log.Fatalln(e) // Handle this ......
 119         }
 120         fmt.Println(exampid + "stomp disconnect complete ...")
 121         // Close the network connection
 122         e = n.Close()
 123         if e != nil {
 124                 log.Fatalln(e) // Handle this ......
 125         }
 126         fmt.Println(exampid + "network close complete ...")
 127
 128         fmt.Println(exampid + "ends ...")
 129 }