Synchronized subscriber in CL

;;; -*- Mode:Lisp; Syntax:ANSI-Common-Lisp; -*-
;;; Synchronized subscriber in Common Lisp
;;; Kamil Shakirov <moc.liamg|08slimak#moc.liamg|08slimak>

(defpackage #:zguide.syncsub
(:nicknames #:syncsub)
(:use #:cl #:zhelpers)
(:export #:main))

(in-package :zguide.syncsub)

(defun main ()
(zmq:with-context (context 1)
;; First, connect our subscriber socket
(zmq:with-socket (subscriber context zmq:sub)
(zmq:connect subscriber "tcp://localhost:5561")
(zmq:setsockopt subscriber zmq:subscribe "")

;; Second, synchronize with publisher
(zmq:with-socket (syncclient context zmq:req)
(zmq:connect syncclient "tcp://localhost:5562")

;; - send a synchronization request
(let ((msg (make-instance 'zmq:msg :data "")))
(zmq:send syncclient msg))

;; - wait for synchronization reply
(let ((msg (make-instance 'zmq:msg)))
(zmq:recv syncclient msg))

;; Third, get our updates and report how many we got
(let ((updates 0))
(let ((msg (make-instance 'zmq:msg)))
(zmq:recv subscriber msg)
(when (string= "END" (zmq:msg-data-as-string msg))
(incf updates)))

(message "Received ~D updates~%" updates)))))