src/java.desktop/windows/classes/sun/print/PrintServiceLookupProvider.java

*** 94,108 ****
              // There's no capability for Win98 to refresh printers.
              // See "OpenPrinter" for more info.
              if (osName != null && osName.startsWith("Windows 98")) {
                  return;
              }
!             // start the printer listener thread
              Thread thr = new Thread(null, new PrinterChangeListener(),
                                      "PrinterListener", 0, false);
              thr.setDaemon(true);
              thr.start();
          } /* else condition ought to never happen! */
      }
  
      /* Want the PrintService which is default print service to have
       * equality of reference with the equivalent in list of print services
--- 94,114 ----
              // There's no capability for Win98 to refresh printers.
              // See "OpenPrinter" for more info.
              if (osName != null && osName.startsWith("Windows 98")) {
                  return;
              }
!             // start the local printer listener thread
              Thread thr = new Thread(null, new PrinterChangeListener(),
                                      "PrinterListener", 0, false);
              thr.setDaemon(true);
              thr.start();
+ 
+             // start the remote printer listener thread
+             Thread remThr = new Thread(null, new RemotePrinterChangeListener(),
+                                     "RemotePrinterListener", 0, false);
+             remThr.setDaemon(true);
+             remThr.start();
          } /* else condition ought to never happen! */
      }
  
      /* Want the PrintService which is default print service to have
       * equality of reference with the equivalent in list of print services
*** 314,324 ****
          if (defaultPrintService == null) {
              defaultPrintService = new Win32PrintService(defaultPrinter);
          }
          return defaultPrintService;
      }
- 
      class PrinterChangeListener implements Runnable {
          long chgObj;
          PrinterChangeListener() {
              chgObj = notifyFirstPrinterChange(null);
          }
--- 320,329 ----
*** 341,351 ****
--- 346,422 ----
                  }
              }
          }
      }    
  
+     /* Windows provides *PrinterChangeNotification* functions that provides 
+        information about printer status changes of the local printers but not
+        network printers.
+        Alternatively, Windows provides a way thro' which one can get the
+        network printer status changes by using WMI, RegistryKeyChange combination,
+        which is a slightly complex mechanism. 
+        The Windows WMI offers an async and sync method to read thro' registry 
+        via the WQL query. The async method is considered dangerous as it leaves 
+        open a channel until we close it. But the async method has the advantage of 
+        being notified of a change in registry by calling callback without polling for it.
+        The sync method uses the polling mechanism to notify.
+        RegistryValueChange cannot be used in combination with WMI to get registry
+        value change notification because of an error that may be generated because the
+        scope of the query would be too big to handle(at times).
+        Hence an alternative mechanism is choosen via the EnumPrinters by polling for the
+        count of printer status changes(add\remove) and based on it update the printers
+        list.
+     */
+     class RemotePrinterChangeListener implements Runnable {
+         private static final long DELAY = 1000 * 60 * 4; // 4 min pooling
+         private String[] prevRemotePrinters;
+ 
+         RemotePrinterChangeListener() {
+             prevRemotePrinters = GetRemotePrintersNames();
+         }
+ 
+         boolean doCompare(String[] str1, String[] str2) {
+             if(str1.length != str2.length) {
+                 return true;
+             } else {
+                 for(int i = 0;i < str1.length;i++) {
+                     for(int j = 0;j < str2.length;j++) {
+                         if(!str1[i].equals(str2[j])) {
+                             return true;
+                         }
+                     }
+                 }
+             }
+ 
+             return false;
+         }
+ 
+         @Override
+         public void run() {
+             while(true) {
+                 String[] currentRemotePrinters = GetRemotePrintersNames();
+                 if(doCompare(prevRemotePrinters, currentRemotePrinters)) {
+ 
+                     // updated the printers data
+                     // printers list now contains both local and network printer data
+                     refreshServices();
+ 
+                     // store the current data for next comparison
+                     prevRemotePrinters = currentRemotePrinters;
+                 }
+ 
+                 try {
+                     Thread.sleep(DELAY);
+                 } catch (InterruptedException e) {
+                     break;
+                 }
+             }
+         }
+     }
+ 
      private native String getDefaultPrinterName();
      private native String[] getAllPrinterNames();
      private native long notifyFirstPrinterChange(String printer);
      private native void notifyClosePrinterChange(long chgObj);
      private native int notifyPrinterChange(long chgObj);
+     private native String[] GetRemotePrintersNames();
  }