func recv(conn *stompngo.Connection, s int) {
	ltag := tag + "-recv"

	ll.Printf("%stag:%s connsess:%s receiver_starts s:%d\n",
		exampid, ltag, conn.Session(),
		s)

	// Setup Headers ...
	id := stompngo.Uuid() // Use package convenience function for unique ID
	d := sngecomm.Dest()
	ackMode = sngecomm.AckMode() // get ack mode

	pbc := sngecomm.Pbc() // Print byte count

	sc := sngecomm.HandleSubscribe(conn, d, id, ackMode)
	// Receive loop.
	mc := 0
	var md stompngo.MessageData
	for {
		select {
		case md = <-sc: // Read a messagedata struct, with a MESSAGE frame
		case md = <-conn.MessageData: // Read a messagedata struct, with a ERROR/RECEIPT frame
			// Frames RECEIPT or ERROR not expected here
			ll.Fatalf("%stag:%s connsess:%s bad_frame md:%v",
				exampid, ltag, conn.Session(),
				md) // Handle this ......
		}
		//
		mc++
		if md.Error != nil {
			ll.Fatalf("%stag:%s connsess:%s error_read error:%v",
				exampid, ltag, conn.Session(),
				md.Error) // Handle this ......
		}
		ll.Printf("%stag:%s connsess:%s received_message s:%d id:%s mc:%d\n",
			exampid, ltag, conn.Session(),
			s, id, mc)
		if pbc > 0 {
			maxlen := pbc
			if len(md.Message.Body) < maxlen {
				maxlen = len(md.Message.Body)
			}
			ss := string(md.Message.Body[0:maxlen])
			ll.Printf("%stag:%s connsess:%s payload body:%s\n",
				exampid, tag, conn.Session(),
				ss)
		}

		// time.Sleep(3 * time.Second) // A very arbitrary number
		// time.Sleep(500 * time.Millisecond) // A very arbitrary number
		runtime.Gosched()
		time.Sleep(1500 * time.Millisecond) // A very arbitrary number
		runtime.Gosched()
		if ackMode != "auto" {
			sngecomm.HandleAck(conn, md.Message.Headers, id)
			ll.Printf("%stag:%s connsess:%s ack_complete s:%d id:%s mc:%d\n",
				exampid, ltag, conn.Session(),
				s, id, mc)
		}
		runtime.Gosched()
	}
}
Exemple #2
0
// Connect to a STOMP broker, receive some messages, ACK them, and disconnect.
func main() {

	st := time.Now()

	// Standard example connect sequence
	n, conn, e := sngecomm.CommonConnect(exampid, tag, ll)
	if e != nil {
		ll.Fatalf("%stag:%s connsess:%s main_on_connect error:%v",
			exampid, tag, sngecomm.Lcs,
			e.Error()) // Handle this ......
	}

	pbc := sngecomm.Pbc() // Print byte count

	// *NOTE* your application functionaltiy goes here!
	// With Stomp, you must SUBSCRIBE to a destination in order to receive.
	// Subscribe returns a channel of MessageData struct.
	// Here we use a common utility routine to handle the differing subscribe
	// requirements of each protocol level.
	d := senv.Dest()
	id := stompngo.Uuid()
	sc := sngecomm.HandleSubscribe(conn, d, id, "client")
	ll.Printf("%stag:%s connsess:%s main_subscribe_complete\n",
		exampid, tag, conn.Session())
	// Read data from the returned channel
	var md stompngo.MessageData
	for i := 1; i <= senv.Nmsgs(); i++ {

		select {
		case md = <-sc:
		case md = <-conn.MessageData:
			// Frames RECEIPT or ERROR not expected here
			ll.Fatalf("%stag:%s connsess:%s main_channel_frame error:%v",
				exampid, tag, conn.Session(),
				e.Error()) // Handle this ......
		}

		ll.Printf("%stag:%s connsess:%s main_channel_read_complete\n",
			exampid, tag, conn.Session())
		// MessageData has two components:
		// a) a Message struct
		// b) an Error value.  Check the error value as usual
		if md.Error != nil {
			ll.Fatalf("%stag:%s connsess:%s main_channel_read error:%v",
				exampid, tag, conn.Session(),
				e.Error()) // Handle this ......
		}
		//
		ll.Printf("%stag:%s connsess:%s frame_type:%v\n",
			exampid, tag, conn.Session(),
			md.Message.Command)
		if md.Message.Command != stompngo.MESSAGE {
			ll.Fatalf("%stag:%s connsess:%s bad_frame frame:%v",
				exampid, tag, conn.Session(),
				md.Message.Command) // Handle this ......
		}
		wh := md.Message.Headers
		for j := 0; j < len(wh)-1; j += 2 {
			ll.Printf("%stag:%s connsess:%s header:%s:%s\n",
				exampid, tag, conn.Session(),
				wh[j], wh[j+1])
		}
		if pbc > 0 {
			maxlen := pbc
			if len(md.Message.Body) < maxlen {
				maxlen = len(md.Message.Body)
			}
			ss := string(md.Message.Body[0:maxlen])
			ll.Printf("%stag:%s connsess:%s message_payload body:%s\n",
				exampid, tag, conn.Session(),
				ss)

		}
		// ACK the message just received.
		// Agiain we use a utility routine to handle the different requirements
		// of the protocol versions.
		sngecomm.HandleAck(conn, md.Message.Headers, id)
		ll.Printf("%stag:%s connsess:%s  ack_complete\n",
			exampid, tag, conn.Session())
	}
	// It is polite to unsubscribe, although unnecessary if a disconnect follows.
	// Again we use a utility routine to handle the different protocol level
	// requirements.
	sngecomm.HandleUnsubscribe(conn, d, id)
	ll.Printf("%stag:%s connsess:%s stomp_unsubscribe_complete\n",
		exampid, tag, conn.Session())

	// Standard example disconnect sequence
	e = sngecomm.CommonDisconnect(n, conn, exampid, tag, ll)
	if e != nil {
		ll.Fatalf("%stag:%s connsess:%s disconnect error:%v",
			exampid, tag, conn.Session(),
			e.Error()) // Handle this ......
	}

	ll.Printf("%stag:%s connsess:%s main_elapsed:%v\n",
		exampid, tag, conn.Session(),
		time.Now().Sub(st))

}
/*
runReceive receives all messages from a specified queue.
*/
func runReceive(conn *stompngo.Connection, q int, w *sync.WaitGroup) {
	ltag := tag + "-runreceive"

	qns := fmt.Sprintf("%d", q) // queue number
	id := stompngo.Uuid()       // A unique subscription ID
	d := sngecomm.Dest() + "." + qns

	ll.Printf("%stag:%s connsess:%s starts id:%s qns:%s d:%s\n",
		exampid, ltag, conn.Session(),
		id, qns, d)

	// Subscribe (use common helper)
	sc := sngecomm.HandleSubscribe(conn, d, id, sngecomm.AckMode())
	ll.Printf("%stag:%s connsess:%s subscribe_done id:%s qns:%s d:%s\n",
		exampid, ltag, conn.Session(),
		id, qns, d)

	//
	tmr := time.NewTimer(100 * time.Hour)

	pbc := sngecomm.Pbc() // Print byte count

	nmsgs := senv.Nmsgs()

	// Receive loop
	var md stompngo.MessageData
	for mc := 1; mc <= nmsgs; mc++ {
		ll.Printf("%stag:%s connsess:%s chanchek id:%s qns:%s lensc:%d capsc:%d\n",
			exampid, ltag, conn.Session(),
			id, qns, len(sc), cap(sc))
		select {
		case md = <-sc:
		case md = <-conn.MessageData:
			// Frames RECEIPT or ERROR not expected here
			ll.Fatalf("%stag:%s connsess:%s send_error qns:%v md:%v",
				exampid, ltag, conn.Session(),
				qns, md) // Handle this ......
		}

		if md.Error != nil {
			ll.Fatalf("%stag:%s connsess:%s receive_error qns:%v error:%v\n",
				exampid, ltag, conn.Session(),
				qns, md.Error)
		}

		// Process the inbound message .................
		ll.Printf("%stag:%s connsess:%s inbound id:%s qns:%s mc:%d\n",
			exampid, ltag, conn.Session(),
			id, qns, mc)
		// Sanity check the message Command, and the queue and message numbers
		mns := fmt.Sprintf("%d", mc) // string message number
		if md.Message.Command != stompngo.MESSAGE {
			ll.Fatalf("%stag:%s connsess:%s bad_frame qns:%s mc:%d md:%v\n",
				exampid, ltag, conn.Session(),
				qns, mc, md)
		}
		if !md.Message.Headers.ContainsKV("qnum", qns) || !md.Message.Headers.ContainsKV("msgnum", mns) {
			ll.Fatalf("%stag:%s connsess:%s dirty_message qns:%v msgnum:%v md:%v",
				exampid, tag, conn.Session(),
				qns, mns, md) // Handle this ......
		}

		sl := len(md.Message.Body)
		if pbc > 0 {
			sl = pbc
			if len(md.Message.Body) < sl {
				sl = len(md.Message.Body)
			}
		}

		ll.Printf("%stag:%s connsess:%s runReceive_recv_message id:%s body:%s qns:%s msgnum:%s\n",
			exampid, ltag, conn.Session(),
			id, string(md.Message.Body[0:sl]), qns,
			md.Message.Headers.Value("msgnum"))

		// Handle ACKs if needed
		if sngecomm.AckMode() != "auto" {
			ah := stompngo.Headers{}
			sngecomm.HandleAck(conn, ah, id)
		}
		if mc == nmsgs {
			break
		}
		if rw {
			dt := time.Duration(sngecomm.ValueBetween(min, max, rf))
			ll.Printf("%stag:%s connsess:%s recv_stagger dt:%v qns:%s mc:%d\n",
				exampid, ltag, conn.Session(),
				dt, qns, mc)
			tmr.Reset(dt)
			_ = <-tmr.C
			runtime.Gosched()
		}
	}
	// Unsubscribe
	sngecomm.HandleUnsubscribe(conn, d, id)

	ll.Printf("%stag:%s connsess:%s runRecieve_ends id:%s qns:%s\n",
		exampid, ltag, conn.Session(),
		id, qns)
	w.Done()
}
Exemple #4
0
// Connect to a STOMP broker, receive some messages and disconnect.
func main() {

	st := time.Now()

	// Standard example connect sequence
	// Use AMQ port here
	n, conn, e := sngecomm.CommonConnect(exampid, tag, ll)
	if e != nil {
		ll.Fatalf("%stag:%s connsess:%s main_on_connect error:%v",
			exampid, tag, sngecomm.Lcs,
			e.Error()) // Handle this ......
	}

	pbc := sngecomm.Pbc() // Print byte count

	// Setup Headers ...
	id := stompngo.Uuid() // Use package convenience function for unique ID
	d := "jms.queue.exampleQueue"
	sc := sngecomm.HandleSubscribe(conn, d, id, "auto")
	ll.Printf("%stag:%s connsess:%s stomp_subscribe_complete\n",
		exampid, tag, conn.Session())

	//
	var md stompngo.MessageData
	// Read data from the returned channel
	for i := 1; i <= nmsgs; i++ {
		select {
		case md = <-sc:
		case md = <-conn.MessageData:
			// Frames RECEIPT or ERROR not expected here
			ll.Fatalf("%stag:%s connsess:%s bad_frame error:%v",
				exampid, tag, conn.Session(),
				e.Error()) // Handle this ......
		}
		ll.Printf("%stag:%s connsess:%s channel_read_complete\n",
			exampid, tag, conn.Session())
		// MessageData has two components:
		// a) a Message struct
		// b) an Error value.  Check the error value as usual
		if md.Error != nil {
			ll.Fatalf("%stag:%s connsess:%s error_read error:%v",
				exampid, tag, conn.Session(),
				e.Error()) // Handle this ......
		}
		ll.Printf("%stag:%s connsess:%s frame_type cmd:%s\n",
			exampid, tag, conn.Session(),
			md.Message.Command)

		if md.Message.Command != stompngo.MESSAGE {
			ll.Fatalf("%stag:%s connsess:%s error_frame_type error:%v",
				exampid, tag, conn.Session(),
				e.Error()) // Handle this ......
		}
		wh := md.Message.Headers
		for j := 0; j < len(wh)-1; j += 2 {
			ll.Printf("%stag:%s connsess:%s Header:%s:%s\n",
				exampid, tag, conn.Session(),
				wh[j], wh[j+1])
		}
		if pbc > 0 {
			maxlen := pbc
			if len(md.Message.Body) < maxlen {
				maxlen = len(md.Message.Body)
			}
			ss := string(md.Message.Body[0:maxlen])
			ll.Printf("%stag:%s connsess:%s payload body:%s\n",
				exampid, tag, conn.Session(),
				ss)
		}
	}

	//
	sngecomm.HandleUnsubscribe(conn, d, id)
	ll.Printf("%stag:%s connsess:%s unsubscribe_complete\n",
		exampid, tag, conn.Session())

	// Standard example disconnect sequence
	e = sngecomm.CommonDisconnect(n, conn, exampid, tag, ll)
	if e != nil {
		ll.Fatalf("%stag:%s connsess:%s main_disconnect error:%v",
			exampid, tag, conn.Session(),
			e.Error()) // Handle this ......
	}

	ll.Printf("%stag:%s connsess:%s main_elapsed:%v\n",
		exampid, tag, conn.Session(),
		time.Now().Sub(st))

}
func runNextQueue(qn int, conn *stompngo.Connection) {

	qns := fmt.Sprintf("%d", qn) // string number of the queue
	conn.SetLogger(ll)           // stompngo logging
	pbc := sngecomm.Pbc()        // Print byte count
	d := senv.Dest() + qns       // Destination
	id := stompngo.Uuid()        // A unique name/id
	nmsgs := qn                  // int number of messages to get, same as queue number
	am := sngecomm.AckMode()     // ACK mode to use on SUBSCRIBE
	nfa := true                  // Need "final" ACK (possiby reset below)
	wh := stompngo.Headers{}     // Starting SUBSCRIBE headers

	// Sanity check ACK mode
	if conn.Protocol() == stompngo.SPL_10 &&
		am == stompngo.AckModeClientIndividual {
		ll.Fatalf("%stag:%s connsess:%s invalid_ack_mode am:%v proto:%v\n",
			exampid, tag, session,
			am, conn.Protocol()) //
	}
	// Do not do final ACK if running ACKs are issued
	if am == stompngo.AckModeClientIndividual ||
		am == stompngo.AckModeAuto {
		nfa = false
	}

	// Show run parameters
	ll.Printf("%stag:%s connsess:%s run_parms\n\tqns:%v\n\tpbc:%v\n\td:%v\n\tid:%v\n\tnmsgs:%v\n\tam:%v\n\tnfa:%v\n\twh:%v\n",
		exampid, tag, session,
		qns, pbc, d, id, nmsgs, am, nfa, wh)

	// Run SUBSCRIBE
	sc := doSubscribe(conn, d, id, am, wh)
	ll.Printf("%stag:%s connsess:%s stomp_subscribe_complete\n",
		exampid, tag, session)

	var md stompngo.MessageData  // Message data from basic read
	var lmd stompngo.MessageData // Possible save (copy) of received data
	mc := 1                      // Initial message number

	// Loop for the requested number of messages
GetLoop:
	for {
		ll.Printf("%stag:%s connsess:%s start_of_read_loop mc:%v nmsgs:%v\n",
			exampid, tag, session, mc, nmsgs)

		mcs := fmt.Sprintf("%d", mc) // string number message count

		// Get something from the stompngo read routine
		select {
		case md = <-sc:
		case md = <-conn.MessageData:
			//
			if md.Message.Command == stompngo.RECEIPT {
				ll.Printf("%stag:%s connsess:%s have_receipt md:%v\n",
					exampid, tag, session,
					md)
				continue GetLoop
			}
			ll.Fatalf("%stag:%s connsess:%s ERROR_frame hdrs:%v body:%v\n",
				exampid, tag, session,
				md.Message.Headers, string(md.Message.Body)) // Handle this ......
		}

		// Save message data for possible use in the final ACK
		if mc == nmsgs && nfa {
			lmd = md // Save last message
		}

		// Basic loop logging
		ll.Printf("%stag:%s connsess:%s channel_read_complete qn:%d mc:%d\n",
			exampid, tag, session,
			qn, mc)
		ll.Printf("%stag:%s connsess:%s message_number:%v\n",
			exampid, tag, session,
			mc)

		// Check if reader returned any error
		if md.Error != nil {
			ll.Fatalf("%stag:%s connsess:%s error_read error:%v",
				exampid, tag, session,
				md.Error) // Handle this ......
		}

		// Show frame type
		ll.Printf("%stag:%s connsess:%s frame_type cmd:%s\n",
			exampid, tag, session,
			md.Message.Command)

		// Pure sanity check:  this should *never* happen based on logic
		// above.
		if md.Message.Command != stompngo.MESSAGE {
			ll.Fatalf("%stag:%s connsess:%s error_frame_type md:%v",
				exampid, tag, session,
				md) // Handle this ......
		}

		// Show Message Headers
		wh := md.Message.Headers
		for j := 0; j < len(wh)-1; j += 2 {
			ll.Printf("%stag:%s connsess:%s Header:%s:%s\n",
				exampid, tag, session,
				wh[j], wh[j+1])
		}
		// Show (part of) Message Body
		if pbc > 0 {
			maxlen := pbc
			if len(md.Message.Body) < maxlen {
				maxlen = len(md.Message.Body)
			}
			ss := string(md.Message.Body[0:maxlen])
			ll.Printf("%stag:%s connsess:%s payload body:%s\n",
				exampid, tag, session,
				ss)
		}

		// Sanity check this message payload
		wm := wlp + mcs // The left part plus the (string) meassage number]
		bm := string(md.Message.Body)
		if bm != wm {
			ll.Fatalf("%stag:%s connsess:%s error_message_payload\n\tGot %s\n\tWant%s\n",
				exampid, tag, session,
				bm, wm) // Handle this ......
		} else {
			ll.Printf("%stag:%s connsess:%s  matched_body_string\n%s\n%s\n",
				exampid, tag, session,
				bm, wm) // Handle this ......)
		}

		// Run individual ACK if required
		if am == stompngo.AckModeClientIndividual {
			wh := md.Message.Headers // Copy Headers
			if ar {                  // ACK receipt wanted
				wh = wh.Add(stompngo.HK_RECEIPT, "rwanted-"+mcs)
			}
			sngecomm.HandleAck(conn, wh, id)
			ll.Printf("%stag:%s connsess:%s  individual_ack_complete mc:%v headers:%v\n",
				exampid, tag, session,
				mc, md.Message.Headers)

		}

		// Check for end of loop condition
		if mc == nmsgs {
			break
		}

		// Increment loop/message counter
		mc++
	}

	qc := make(chan bool)
	go drainSub(session, sc, qc, qn)
	dd := false

	// Issue the final ACK if needed
	if nfa {
		wh := lmd.Message.Headers // Copy Headers
		if ar {                   // ACK receipt wanted
			wh = wh.Add(stompngo.HK_RECEIPT, "rwanted-fin")
		}
		sngecomm.HandleAck(conn, wh, id)
		ll.Printf("%stag:%s connsess:%s  final_ack_complete\n",
			exampid, tag, session)
		if ar {
			ll.Printf("%stag:%s connsess:%s  ack_receive_wait_for_drain qn:%d\n",
				exampid, tag, session,
				qn)
			<-qc // Wait for drainSub
			ll.Printf("%stag:%s connsess:%s  ack_receive_drain_complete qn:%d\n",
				exampid, tag, session,
				qn)
			dd = true
			getReceipt(conn)
		}
	}

	if !dd {
		ll.Printf("%stag:%s connsess:%s  message_loop_wait_for_drain qn:%d\n",
			exampid, tag, session,
			qn)
		<-qc
		ll.Printf("%stag:%s connsess:%s  message_loop_drain_complete qn:%d\n",
			exampid, tag, session,
			qn)
	}

	// Unsubscribe (may be skipped if requested)
	if unsub {
		sngecomm.HandleUnsubscribe(conn, d, id)
		ll.Printf("%stag:%s connsess:%s stomp_unsubscribe_complete\n",
			exampid, tag, session)
	} else {
		ll.Printf("%stag:%s connsess:%s skipping_unsubscribe\n",
			exampid, tag, session)
	}
}
// Asynchronously process all messages for a given subscription.
func receiveWorker(sc <-chan stompngo.MessageData, qns string, nmsgs int,
	qc chan<- bool, conn *stompngo.Connection, id string) {
	//
	ltag := tag + "-receiveWorker"

	tmr := time.NewTimer(100 * time.Hour)

	pbc := sngecomm.Pbc() // Print byte count

	// Receive loop
	var md stompngo.MessageData
	for i := 1; i <= nmsgs; i++ {

		select {
		case md = <-sc:
		case md = <-conn.MessageData:
			// Frames RECEIPT or ERROR not expected here
			ll.Fatalf("%stag:%s connsess:%s bad_frame qns:%v md:%v",
				exampid, ltag, conn.Session(),
				qns, md) // Handle this ......
		}
		if md.Error != nil {
			ll.Fatalf("%stag:%s connsess:%s recv_error qns:%v error:%v",
				exampid, ltag, conn.Session(),
				qns, md.Error) // Handle this ......
		}

		// Sanity check the queue and message numbers
		mns := fmt.Sprintf("%d", i) // message number
		if !md.Message.Headers.ContainsKV("qnum", qns) || !md.Message.Headers.ContainsKV("msgnum", mns) {
			ll.Fatalf("%stag:%s connsess:%s dirty_message qnum:%v msgnum:%v md:%v",
				exampid, ltag, conn.Session(),
				qns, mns, md) // Handle this ......
		}

		// Process the inbound message .................
		sl := len(md.Message.Body)
		if pbc > 0 {
			sl = pbc
			if len(md.Message.Body) < sl {
				sl = len(md.Message.Body)
			}
		}

		// Handle ACKs if needed
		if sngecomm.AckMode() != "auto" {
			ah := []string{}
			sngecomm.HandleAck(conn, ah, id)
		}
		ll.Printf("%stag:%s connsess:%s recv_message body:%s qns:%s msgnum:%s i:%v\n",
			exampid, ltag, conn.Session(),
			string(md.Message.Body[0:sl]),
			qns,
			md.Message.Headers.Value("msgnum"), i)
		if i == nmsgs {
			break
		}
		if rw {
			runtime.Gosched() // yield for this example
			dt := time.Duration(sngecomm.ValueBetween(min, max, rf))
			ll.Printf("%stag:%s connsess:%s recv_stagger dt:%v qns:%s\n",
				exampid, ltag, conn.Session(),
				dt, qns)
			tmr.Reset(dt)
			_ = <-tmr.C
		}
	}
	//
	qc <- true
}
func receiveMessages(conn *stompngo.Connection, qnum int, nc net.Conn) {
	ltag := tag + "-receivemessages"

	qns := fmt.Sprintf("%d", qnum) // queue number
	d := sngecomm.Dest() + "." + qns
	id := stompngo.Uuid() // A unique subscription ID

	ll.Printf("%stag:%s connsess:%s receiveMessages_start id:%s d:%s qnum:%d nmsgs:%d\n",
		exampid, ltag, conn.Session(),
		id, d, qnum, nmsgs)
	// Subscribe
	sc := sngecomm.HandleSubscribe(conn, d, id, sngecomm.AckMode())

	pbc := sngecomm.Pbc() // Print byte count

	//
	tmr := time.NewTimer(100 * time.Hour)
	var md stompngo.MessageData
	for mc := 1; mc <= nmsgs; mc++ {

		select {
		case md = <-sc:
		case md = <-conn.MessageData:
			// Frames RECEIPT or ERROR not expected here
			ll.Fatalf("%stag:%s connsess:%s send_error qns:%v md:%v",
				exampid, ltag, conn.Session(),
				qns, md) // Handle this ......
		}
		if md.Error != nil {
			ll.Fatalf("%stag:%s connsess:%s receive_error qns:%v error:%v\n",
				exampid, ltag, conn.Session(),
				qns, md.Error)
		}

		if md.Message.Command != stompngo.MESSAGE {
			ll.Fatalf("%stag:%s connsess:%s bad_frame qns:%s mc:%d md:%v\n",
				exampid, ltag, conn.Session(),
				qns, mc, md)
		}

		mcs := fmt.Sprintf("%d", mc) // message number
		if !md.Message.Headers.ContainsKV("qnum", qns) || !md.Message.Headers.ContainsKV("msgnum", mcs) {
			ll.Fatalf("%stag:%s connsess:%s dirty_message qns:%v msgnum:%v md:%v",
				exampid, tag, conn.Session(),
				qns, mcs, md) // Handle this ......
		}

		// Process the inbound message .................
		sl := len(md.Message.Body)
		if pbc > 0 {
			sl = pbc
			if len(md.Message.Body) < sl {
				sl = len(md.Message.Body)
			}
		}
		ll.Printf("%stag:%s connsess:%s receiveMessages_msg d:%s body:%s qnum:%d msgnum:%s\n",
			exampid, ltag, conn.Session(),
			d, string(md.Message.Body[0:sl]), qnum,
			md.Message.Headers.Value("msgnum"))
		if mc == nmsgs {
			break
		}
		// Handle ACKs if needed
		if sngecomm.AckMode() != "auto" {
			ah := []string{}
			sngecomm.HandleAck(conn, ah, id)
		}
		if mc == nmsgs {
			break
		}
		//
		if rw {
			runtime.Gosched() // yield for this example
			dt := time.Duration(sngecomm.ValueBetween(min, max, rf))
			ll.Printf("%stag:%s connsess:%s recv_stagger dt:%v qns:%s mc:%d\n",
				exampid, ltag, conn.Session(),
				dt, qns, mc)
			tmr.Reset(dt)
			_ = <-tmr.C
		}
	}
	ll.Printf("%stag:%s connsess:%s end d:%s qnum:%d nmsgs:%d\n",
		exampid, ltag, conn.Session(),
		d, qnum, nmsgs)

	// Unsubscribe
	sngecomm.HandleUnsubscribe(conn, d, id)
	//
}
// Receive messages from a particular queue
func receiver(qn, mc int) {
	ltag := tag + "-receiver"

	qns := fmt.Sprintf("%d", qn) // string queue number
	pbc := sngecomm.Pbc()
	id := stompngo.Uuid() // A unique subscription ID
	d := sngecomm.Dest() + "." + qns

	ll.Printf("%stag:%s connsess:%s queue_info id:%v d:%v qnum:%v mc:%v\n",
		exampid, ltag, conn.Session(),
		id, d, qn, mc)
	// Subscribe
	sc := sngecomm.HandleSubscribe(conn, d, id, sngecomm.AckMode())
	ll.Printf("%stag:%s connsess:%s subscribe_complete id:%v d:%v qnum:%v mc:%v\n",
		exampid, ltag, conn.Session(),
		id, d, qn, mc)
	//
	tmr := time.NewTimer(100 * time.Hour)
	var md stompngo.MessageData
	// Receive loop
	for i := 1; i <= mc; i++ {
		ll.Printf("%stag:%s connsess:%s recv_ranchek id:%v d:%v qnum:%v mc:%v chlen:%v chcap:%v\n",
			exampid, ltag, conn.Session(),
			id, d, qn, mc, len(sc), cap(sc))

		select {
		case md = <-sc:
		case md = <-conn.MessageData:
			// A RECEIPT or ERROR frame is unexpected here
			ll.Fatalf("%stag:%s connsess:%s bad_frame qnum:%v headers:%v body:%s",
				exampid, tag, conn.Session(),
				qn, md.Message.Headers, md.Message.Body) // Handle this ......
		}
		if md.Error != nil {
			ll.Fatalf("%stag:%s connsess:%s recv_error qnum:%v error:%v",
				exampid, tag, conn.Session(),
				qn, md.Error) // Handle this ......
		}

		// Process the inbound message .................
		ll.Printf("%stag:%s connsess:%s recv_message qnum:%v i:%v\n",
			exampid, tag, conn.Session(),
			qn, i)
		if pbc > 0 {
			maxlen := pbc
			if len(md.Message.Body) < maxlen {
				maxlen = len(md.Message.Body)
			}
			ss := string(md.Message.Body[0:maxlen])
			ll.Printf("%stag:%s connsess:%s payload qnum:%v body:%s\n",
				exampid, tag, conn.Session(),
				qn, ss)

		}

		// Sanity check the message Command, and the queue and message numbers
		mns := fmt.Sprintf("%d", i) // message number
		if md.Message.Command != stompngo.MESSAGE {
			ll.Fatalf("%stag:%s connsess:%s bad_frame qnum:%v command:%v headers:%v body:%v\n",
				exampid, tag, conn.Session(),
				qn, md.Message.Command, md.Message.Headers, string(md.Message.Body)) // Handle this ......

		}
		if !md.Message.Headers.ContainsKV("qnum", qns) || !md.Message.Headers.ContainsKV("msgnum", mns) {
			ll.Fatalf("%stag:%s connsess:%s dirty_message qns:%v msgnum:%v command:%v headers:%v body:%v\n",
				exampid, tag, conn.Session(),
				qns, mns, md.Message.Command, md.Message.Headers, string(md.Message.Body)) // Handle this ......) // Handle this ......
		}

		if i == mc {
			break
		}

		if rw {
			dt := time.Duration(sngecomm.ValueBetween(min, max, rf))
			ll.Printf("%stag:%s connsess:%s recv_stagger id:%v d:%v qnum:%v stagger:%v\n",
				exampid, ltag, conn.Session(),
				id, d, qn, dt)
			tmr.Reset(dt)
			_ = <-tmr.C
			runtime.Gosched()
		}

		// Handle ACKs if needed
		if sngecomm.AckMode() != "auto" {
			sngecomm.HandleAck(conn, md.Message.Headers, id)
		}
	}
	// Unsubscribe
	sngecomm.HandleUnsubscribe(conn, d, id)
	ll.Printf("%stag:%s connsess:%s unsubscribe_complete id:%v d:%v qnum:%v mc:%v\n",
		exampid, ltag, conn.Session(),
		id, d, qn, mc)

	// Receiving is done
	ll.Printf("%stag:%s connsess:%s recv_end id:%v d:%v qnum:%v mc:%v\n",
		exampid, ltag, conn.Session(),
		id, d, qn, mc)

	wgr.Done()
}