newlispfanclub.alh.net

Posted: **Thu Dec 05, 2013 3:14 am**

I want to send a message via TCP to remote server. This message consists of a few fields, some fields are sting, some are number. My old way is to pack one field and then send it. e.g.

Code: Select all

(define (send-message type content)
  ;; send SOH 
  (unless (net-send (self 4) SOH) (throw-error (string "send soh failed: " (net-error)))) 
  ;; send length 
  (unless (net-send (self 4) (hex-str (+ 10 (length content)) 4)) (throw-error (string "send length failed: " (net-error))))  
  ;; send type 
  (unless (net-send (self 4) type) (throw-error (string "send type failed: " (net-error))))  
  ;; send content
  (unless (net-send (self 4) content) (throw-error (string "send content failed: " (net-error))))                                                                              
  ;; send checksum 
  (let (checksum-value (cal-checksum (total2 (append type content)))) 
    (unless (net-send (self 4) (hex-str checksum-value 2)) (throw-error (string "send checksumfailed: " (net-error)))))                                                        
  ;; send ETX                                                                                                                                                                    
 (unless (net-send (self 4) ETX) (throw-error (string "send etx failed: " (net-error)))))

But I want to pack all fields in one string buffer and send them one time. How to do this?

Posted: **Thu Dec 05, 2013 12:00 pm**

Got it. just use (string ) to contruct it.

Code: Select all

(define (send-message type content)
  (letn ((checksum-value (hex-str (cal-checksum (total2 (append type content))) 2))
	 (str-buffer (string (pack "b" 1) (format "%s%s%s%s" (hex-str (+ 10 (length content)) 4) type content checksum-value) (pack "b" 3))))
	 (let (r (net-send (self 4) str-buffer))
	   (if r
	       (log (format "sent message succeeded, size is: %llu" r))
	     (throw-error (string "send message failed: " (net-error)))))
	))

newlispfanclub.alh.net

pack all fields into one string buffer

pack all fields into one string buffer

Re: pack all fields into one string buffer