Comments on Joey's Scribble's: Monitor a Directory for Changes using Java

How can I set up to watch the directory recursivel...

2010-02-28T06:33:08.116-05:00

How can I set up to watch the directory recursively? Where do I need to add the boolean flag?

@Develper Dude - Yes, but the problem is what we c...

2009-10-25T19:23:19.987-04:00

@Develper Dude - Yes, but the problem is what we can do with Watchable cannot be completely achieved with Observable and vice versa. Each is higly specific or highly vague. But by the end of the day, we can complete what we started with the existing APIs but will be better if they much more generic.

To be fair, there other ways of doing something li...

2009-10-23T11:16:16.758-04:00

To be fair, there other ways of doing something like this in general with an Observer/Observable, or better yet with a ChangeListener (the latter is usually more specific and you don't get bombarded with as many events), but the pattern of Watchables/Watchers/WatchService where you register your interest in specific events seems to be more powerful and flexible.

Of course, there are APIs like the EventBus or Spring Messaging, or various PubSub systems that could be used too. But in general, not just with this particular usage/pattern, I have found many different implementations of patterns that are too specific to a particular usage when with a bit of refactoring and thought they could be reused in a broader domain of problems. Given that, I wish devs would keep that in mind when they come up with these solutions so we could reuse them elsewhere.

@Developer Dude - That were by initial thoughts to...

2009-10-19T20:37:02.073-04:00

@Developer Dude - That were by initial thoughts too. Why only NIO ? They could even potentially merge Observable to Watcher and make this as a generic API which can watch a directory, a object or anything it can support. That would be pretty cool.

Why does this have to be only in NIO? Why not mak...

2009-10-19T19:30:30.647-04:00

Why does this have to be only in NIO?

Why not make this a general interface that could be used outside of NIO? I know - I probably could use it elsewhere, but it seems to me that too many nice ideas like this wind up being implemented with too narrow of a focus, and then someone else has to come along and either adapt it to some other use, or reinvent the wheel elsewhere.

My point is that there are other services outside of NIO that could bear watching, that could implement Watchable. I have a number of processes where I would like something like this maybe as an interface/adapter to the EventBus.

From JDK7 API Doc: "Platform dependencies The im...

2009-10-19T05:45:48.854-04:00

From JDK7 API Doc:

"Platform dependencies

The implementation that observes events from the file system is intended to map directly on to the native file event notification facility where available, or to use a primitive mechanism, such as polling, when a native facility is not available. Consequently, many of the details on how events are detected, their timeliness, and whether their ordering is preserved are highly implementation specific. For example, when a file in a watched directory is modified then it may result in a single ENTRY_MODIFY event in some implementations but several events in other implementations. Short-lived files (meaning files that are deleted very quickly after they are created) may not be detected by primitive implementations that periodically poll the file system to detect changes.

If a watched file is not located on a local storage device then it is implementation specific if changes to the file can be detected. In particular, it is not required that changes to files carried out on remote systems be detected."

What does the API do when the FS doesn't support n...

2009-10-18T19:51:55.453-04:00

What does the API do when the FS doesn't support notifications ?