Multiple events triggered by fileSystemWatch er

[Abel Chan]

Hi there,

I was trying to write a simple NT services using .NET 2.0 and
fileSystemWatch er control. The goal is to poll documents from a watch
directory and ftp them to a remote web site.

I created a Windows Services project using VS2005. Drag a fileSystemWatch er
control to the designer and added the following code. Here is what I found
out when I create a new file under the watch directory:
1) Using notepad - OnCreate event triggered 2 times. OnChange event
triggered 3 times.
2) Pipe a new file, for example, dir > c:\[watchdir]\temp.txt - OnCreate
event triggered 1 time. OnChange event triggered 3 times.

If I modify a file under the watch directory, Onchange event triggered 2
times.

I think the OnCreate event should work OK. It should be able to pick up new
file and just fire OnCreate event once. Inside the OnCreate event, I can FTP
the file to the site I want.

However, what if user wants to redrop an updated file with the same filename
to the watch directory? How can I reduce the OnChange event to only fire
once? I looked at the MSDN and it states that multiple events could be
triggered but it doesn't provide a solution.

Could you help? If I can't resolve this, I might need to use another
solution besides fileSystemWatch er control. I don't want to post the same
document 2 to 3 times for no reason.

Thanks.

Abel Chan

// Extracted code
private void InitializeCompo nent()
{
this.fileSystem WatcherFTP = new System.IO.FileS ystemWatcher();

((System.Compon entModel.ISuppo rtInitialize)(t his.fileSystemW atcherFTP)).Beg inInit();
//
// fileSystemWatch erFTP
//
this.fileSystem WatcherFTP.Enab leRaisingEvents = true;
this.fileSystem WatcherFTP.Noti fyFilter =
((System.IO.Not ifyFilters)((Sy stem.IO.NotifyF ilters.FileName |
System.IO.Notif yFilters.LastWr ite)));
this.fileSystem WatcherFTP.Chan ged += new
System.IO.FileS ystemEventHandl er(this.fileSys temWatcherFTP_C hanged);
this.fileSystem WatcherFTP.Crea ted += new
System.IO.FileS ystemEventHandl er(this.fileSys temWatcherFTP_C reate);

//this.fileSystem WatcherFTP.Wait ForChanged(Syst em.IO.WatcherCh angeTypes.Creat ed | System.IO.Watch erChangeTypes.C hanged);

//
// ServiceFTP
//
this.ServiceNam e = "ServiceFTP ";

((System.Compon entModel.ISuppo rtInitialize)(t his.fileSystemW atcherFTP)).End Init();

}

[Luke Zhang [MSFT]]

Hello,

This is a known issue. By design, the framework is passing through the
native OS events, which may be any number of things, depending on the way
the file was changed/Created. A work around is to record last file name
"catched" by the control and exact "catch" time. If a second event has same
filename and similiar time, that event will be ignored.

Regards,

Luke Zhang
Microsoft Online Community Support

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