CUPS API: subscribe event

[Michael Sweet]

Rytis wrote:
> Uh, it's more complicated than i thought. Anyway, i've rethinked what
> i whant to do so.. what i need is to get notification whenever
> printer completes a job. I would also need id of completed job. Is
> that possible? And how can i achieve that?

OK, to be notified via IPP_GET_NOTIFICATIONS for all printers, use:

     /* Create a subscription for job-completed events and return the 
subscription-id value or 0 on error */
     int
     create_subscription(void)
     {
       http_t *http;
       ipp_t *request, *response;
       ipp_attribute_t *attr;
       int subscription_id;


       http = httpConnectEncrypt(cupsServer(), ippPort(), cupsEncryption());

       request = ippNewRequest(IPP_CREATE_PRINTER_SUBSCRIPTION);

       ippAddString(request, IPP_TAG_OPERATION, IPP_TAG_URI,
                    "printer-uri", NULL, "ipp://localhost/printers");
       ippAddString(request, IPP_TAG_OPERATION, IPP_TAG_NAME,
                    "requesting-user-name", NULL, cupsUser());

       ippAddString(request, IPP_TAG_SUBSCRIPTION, IPP_TAG_KEYWORD,
                    "notify-pull-method", NULL, "ippget");
       ippAddString(request, IPP_TAG_SUBSCRIPTION, IPP_TAG_KEYWORD,
                    "notify-events", NULL, "job-completed");

       response = cupsDoRequest(http, request, "/printers");

       attr = ippFindAttribute(response, "subscription-id", 
IPP_TAG_INTEGER);
       if (attr)
         subscription_id = attr->values[0].integer;
       else
         subscription_id = 0;

       ippDelete(response);
       httpClose(http);

       return (subscription_id);
     }

You can then gather the events using the IPP_GET_NOTIFICATIONS
operation:

     /* Show job-completed events for the given subscription-id and 
return the number of events seen */
     int
     show_events(int subscription_id)
     {
       int num_events = 0;
       http_t *http;
       ipp_t *request, *response;
       ipp_attribute_t *attr;
       int subscription_id;


       http = httpConnectEncrypt(cupsServer(), ippPort(), cupsEncryption());

       request = ippNewRequest(IPP_GET_NOTIFICATIONS);

       ippAddString(request, IPP_TAG_OPERATION, IPP_TAG_URI,
                    "printer-uri", NULL, "ipp://localhost/printers");
       ippAddString(request, IPP_TAG_OPERATION, IPP_TAG_NAME,
                    "requesting-user-name", NULL, cupsUser());
       ippAddInteger(request, IPP_TAG_OPERATION, IPP_TAG_INTEGER,
                     "subscription-id", subscription_id);

       response = cupsDoRequest(http, request, "/printers");

       if (response)
       {
        /*
         * Loop through the response attributes...
         */

         for (attr = response->attrs; attr; attr = attr->next)
         {
          /*
           * Skip everything up to the next event notification...
           */

           if (attr->group_tag != IPP_TAG_EVENT_NOTIFICATION)
             continue;

          /*
           * Bump the event counter and then look at the attributes
           * for this event...
           */

           num_events ++;

           while (attr && attr->group_tag == IPP_TAG_EVENT_NOTIFICATION)
           {
             if (!strcmp(attr->name, "job-id") && attr->value_tag == 
IPP_TAG_INTEGER)
               printf("Job %d has completed!\n", attr->values[0].integer);

             attr = attr->next;
           }

           if (!attr)
             break;
         }

         ippDelete(response);
       }

       httpClose(http);

       return (num_events);
     }

This code is all untested (just typed it into this email), so there
might be mistakes, but hopefully it will show you the basics...

-- 
______________________________________________________________________
Michael Sweet, Easy Software Products           mike at easysw dot com
Internet Printing and Document Software          http://www.easysw.com