[zeromq-dev] Question about the PUBSUB design pattern when server restarts.

[Janak Raja]

Hello Joshua, 

  Thanks for your response. I donot care when subscriber gets the data as 
sequence for my publisher is infinite. Meaning no Start / no End.  

   How do I close this previous queue ?
   Even though I stop/start publisher, does it still maintain a state of the 
previously connected subscriber and their queue ? 
   Any suggestion on how to solve this would be very helpful ? 
 
Thanks,
Janak



________________________________
From: Joshua Foster <jhawk28 at gmail.com>
To: ZeroMQ development list <zeromq-dev at lists.zeromq.org>
Sent: Thu, November 11, 2010 1:19:27 PM
Subject: Re: [zeromq-dev] Question about the PUBSUB design pattern when server 
restarts.

If you want the subscriber to pick up where it last left off, be     sure to set 
the identity. The publisher is probably creating a new     queue with the 
"second" subscriber, but leaving the previous queue     open. The previous queue 
is the one that continues to grow (causing     memory to increase).

Joshua

On 11/11/2010 1:53 PM, Janak Raja wrote: 
Hello, 
>
>
>  I recently came across zeroMQ and wanted to understand on           what will 
>be the behavior for PUBSUB design pattern when PUB           goes down for more 
>than 2 minutes.
>
>
>  I tried wu example with a little modification to send           packets 
>continuously. Please let me know what I am doing wrong           in this.
>
>
>  Do I have to call connect from client side after every           s_recv call 
>? 
>  Currently, I see that if I dont call connect on SUB and           PUB stops 
>and 2 minutes later starts again, memory usage on           pub keeps on 
>increasing ? May be, its because it might be           keeping it in queue for 
>the sub to get the data.
>
>
>  Please advice, 
>
>
>  Here is the Publisher code:
>     //
>//  Weather update server
>//  Binds PUB socket to tcp://*:5556
>//  Publishes random weather updates
>//
>#include "zhelpers.h"
>
>
>int main () {
>    //  Prepare our context and publisher
>    void *context = zmq_init (1);
>    void *publisher = zmq_socket (context, ZMQ_PUB);
>    zmq_bind (publisher, "tcp://*:5556");
>    zmq_bind (publisher, "ipc://weather.ipc");
>
>
>    //  Initialize random number generator
>    srandom ((unsigned) time (NULL));
>    while (1) {
>        //  Get values that will fool the boss
>        int zipcode, temperature, relhumidity;
>        zipcode     = within (100000);
>        temperature = within (215) - 80;
>        relhumidity = within (50) + 10;
>
>
>        //  Send message to all subscribers
>        char update [20];
>        sprintf (update, "%05d %d %d", zipcode,           temperature, 
>relhumidity);
>        s_send (publisher, update);
>    }
>    zmq_close (publisher);
>    zmq_term (context);
>    return 0;
>}
>
>
>
>
>
>
>
>
>Subscriber code:
>  //
>//  Weather update client
>//  Connects SUB socket to tcp://localhost:5556
>//  Collects weather updates and finds avg temp in zipcode
>//
>#include "zhelpers.h"
>
>
>int main (int argc, char *argv[])
>{
>    void *context = zmq_init (1);
>
>
>    //  Socket to talk to server
>    printf ("Collecting updates from weather server...\n");
>    void *subscriber = zmq_socket (context, ZMQ_SUB);
>    zmq_connect (subscriber, "tcp://localhost:5556");
>
>
>    //  Subscribe to zipcode, default is NYC, 10001
>    char *filter = (argc > 1)? argv [1]: "10001 ";
>    zmq_setsockopt (subscriber, ZMQ_SUBSCRIBE, filter,           strlen 
>(filter));
>    while(1)
>    {
>       //  Process 100 updates
>       int update_nbr;
>       long total_temp = 0;
>       for (update_nbr = 0; update_nbr < 100;           update_nbr++) {
>           char *string = s_recv (subscriber);
>           int zipcode, temperature, relhumidity;
>           sscanf (string, "%d %d %d",
>               &zipcode, &temperature,           &relhumidity);
>           total_temp += temperature;
>           free (string);
>       }
>       printf ("Average temperature for zipcode '%s' was           %dF\n",
>           filter, (int) (total_temp / update_nbr));
>    }
>    zmq_close (subscriber);
>    zmq_term (context);
>    return 0;
>}
>
>
>
>
>Thanks,
>Janak
>
> _______________________________________________ zeromq-dev mailing list 
>zeromq-dev at lists.zeromq.org http://lists.zeromq.org/mailman/listinfo/zeromq-dev 
>



      
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