RE: Monitoring a file for changes from Java?

["Gary L Peskin" <garyp@xxxxxxxxxxxx>]

James -- I would say the latter.

If you look in the javadoc for the AS400File class, it says "AS400File
objects generate the following events:  FileEvent ..."  When you add a
listener via AddFileListener, you are adding a listener to the AS400File
object, not to the iSeries file itself.  Whenever a change is made THROUGH
the AS400File object, your listener will be fired.  But, changes made to the
file from other sources won't fire your listener because those other sources
don't know anything about your listener.  The AS400File object doesn't have
any sort of capability to sit on a file and watch for changes and then fire
your listener.

About all I can think of off the top of my head to accomplish what you want
is to set up some type of journal receiver exit program that would fire your
listener whenever a change is made.  This, of course, requires journalling
the file.

HTH,
Gary


> -----Original Message-----
> From: java400-l-bounces@xxxxxxxxxxxx 
> [mailto:java400-l-bounces@xxxxxxxxxxxx] On Behalf Of James H H Lampert
> Sent: Monday, December 13, 2004 9:42 AM
> To: java400-l@xxxxxxxxxxxx
> Subject: Monitoring a file for changes from Java?
> 
> I note that the Toolbox has a FileListener interface, and the 
> AS400File class has an AddFileListener method.
> 
> I tried implementing the interface from my test class, and 
> while I then received a "FileOpened" event as soon as the 
> test class opened the file, that was about all I got. I was 
> hoping to receive a "FileModified" event when I updated a 
> record from QuestView in another terminal session, but it 
> didn't get ANY events from actions taken elsewhere.
> 
> Am I doing something wrong, or do I just have unrealistically 
> high expectations?
> 
> The test class now looks like:
>   import com.ibm.as400.access.*;
>   class test03 implements FileListener {
>      public static void main (String args[]) {
>          System.out.println("I like spam!");
>          AS400 as400 = new AS400("localhost");
>          System.out.println("CCSID = " + as400.getCcsid());
>          QSYSObjectPathName fileName = new 
> QSYSObjectPathName("AQUESTVIEW", "VIEWCUS", "FILE");
>          System.out.println("Filename = " + fileName.getPath());
>          SequentialFile file = new SequentialFile(as400, 
> fileName.getPath());
>          file.addFileListener(new test03());
>          AS400FileRecordDescription recDes = new 
> AS400FileRecordDescription(as400, fileName.getPath());
>          try {
>              RecordFormat recFmt = recDes.retrieveRecordFormat()[0];
>              System.out.println("Format = " + recFmt.getName());
>              file.setRecordFormat(recFmt);
>              file.open(SequentialFile.READ_ONLY, 1, 
> SequentialFile.COMMIT_LOCK_LEVEL_NONE);
>              Record data = file.readNext();
>              while (data != null) {
>                  System.out.println((String) data.getField("CUNAME"));
>                  data = file.readNext();
>              }
>              System.out.println("Going to sleep");
>              try {Thread.sleep((long)60000);} 
> catch(InterruptedException
> ie) {System.out.println("Interrupted");}
>              System.out.println("Waking up!");
>              as400.disconnectAllServices();
>          } catch (Exception e) {e.printStackTrace();}
>      }
> 
> --
> JHHL
> 
> 
> --
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