What is the best use of FileSystemWatcher?

Question

I want to monitor a folder for new new xml files that are being added. What is the best syntax for this operation. Im a little confused about the whole class in general.

Lalit M · Answer

Best Practices for FileSystemWatcher 1. Use a shared file queue and only add to the queue in the event handlers as stated in here : and to avoid the buffer over-flow limitations and file open limitations. 2. Use two separate FileSystemWatchers to monitor a folder; one for files and one for folders. You need a separate one for folders because a move (cut and paste) operation on a folder will not always generate events for the individual files within the moved folder but only the renamed event for the folder name. Thus you will have to call GetFiles() yourself. 3. To minimize duplicate events do not edit the shared queue but remove duplicates before adding to the queue with a simple string dictionary of order; save the last 5 or 10 file names with the TimeStamp and if the same file name occurs within the last 500 ms than do not add to the queue. This is all needed because of the following limitations I have come across: Issues with FileSystemWatcher: 1. Some File / Directory events result in duplicate events being raised. Example: Edit a file in Notepad and you will get duplicate events. Edit a file in MS Word and you will get multiple events as it uses a temp file in that folder (create change rename delete). For example when a file is moved from one directory to another several OnChanged and some OnCreated and OnDeleted events might be raised. Likewise some applications (for example antivirus software) might cause additional file system events that are detected by FileSystemWatcher. 2. If my process changes the file the FSW calls me. How do I know I was the only one who changed it? 3. Can get buffer over-flow quite easily. 4. Files are not always closed when an event is raised. 5. When moving a watched subfolder within a watched folder the files are not detected BUT new files are detected if a non-watched folder is moved into a watched folder.