IFileEventNotifier

IFileEventNotifier is a service created to give an interface to the System.IO.FileSystemWatcher.

The default implementation is FileEventNotifier.

Interface Members

IFileEventNotifier contains only 2 methods:

• Subscribe(FileWatchInfo)
• Unsubscribe(FileWatchInfo)

The FileWatchInfo to unsubscribe must be the same object as the one used to subscribe. If it's not, an InvalidFileWatchInfoException will be thrown.

FileWatchInfo

FileWatchInfo contains all data regarding a watched file, the class is needed to subscribe and unsubscribe a watch.

It's most important properties are the path, the filter, the changes to report, and the eventhandler to call.

Important

When initializing a new instance of FileWatchInfo:

• A path leading to a directory must always end with '\'
• A path leading to a file must never end with '\'

This is especially necessairy if the path-to-watch is not available on the sytem at the time of FileWatchInfo's initialization, because then FileWatchInfo is not able to know if the path is a file or directory. This could lead to unexpected results.

FileEventNotifier

Features

Watch files/directories

FileEventNotifier is just like FileSystemWatcher able to watch changes on files and/or directories.

Subscribe to unavailable paths

FileEventNotifier supports subsriptions for unavailable paths. The path will be watched as soon as it comes available.

Autorestore on path lost/retrieved

Useful feature for watching files/directories on network shares, removable disks, ramdisks, ...

When such a path is lost, the FileEventNotifier will autorestore the watch as soon as the path is available again.

Events on path lost/retrieved

FileEventNotifier will raise an event if a path is lost or retrieved.

One event per change

Only one event per change is sent.

Example: when a new file is created, a single Created-event will be sent in stead of a the 3 events Created, Renamed, and Changed (which is how some applications create files).

Advanced filtering

FileEventNotifier supports multiple filters. Filters are case sensitive and can contain wildcards.

The following table comes straight from MSDN, and demonstrates the use of wildcards:

No events when filesize is increasing

No events are raised when the filesize is still increasing.

This is especially useful when the user creates a new large file in the watched path. The Created event will only be raised when the file is complete, this makes it save to immediately read tags or parse content from the file.

The feature only works for files.

Internal error handling

All errorhandling is kept internal.

Limitations

NTFS Only

The FAT file system is not supported.

The FileEventNotifier will throw a NotSupportedDriveTypeException if such a path is subscribed,

unless the path is specified by UNC (meaning the path is not watched, and without the subscriber knowing).