[AccessD] DirWatcher - was RE: Cool stuff - was RE: using a dtsx in .Net

Just an FYI, the dirwatcher com object from the webcast apparently can be
used "simultaneously" from Access.  I created a form with two text controls.
Each text control creates an instance of the referenced com object and
passes in whatever you type in as a directory.  If you pass in an invalid
dir name it errors, else it watches.  I then created two empty directories
and tested by creating new text files in each directory.  The correct events
fired and I was notified of the appearance of a file (and it's name) in the
correct watched directory.  

And of course this does require a completely external "watcher widget" which
has to be registered etc., at least for use in Access.

WARNING... The COM object DELETES the file behind itself so it is NOT
appropriate for use "as is", nor did I expect it to be, but it does function
inside of VBA and it can do so multi-instanced.

The following is the code in the test form that I created:

Option Compare Database
Option Explicit

Dim WithEvents fDirWatcher1 As DropDirMonitor.DirWatcher
Dim WithEvents fDirWatcher2 As DropDirMonitor.DirWatcher

Private Sub fDirWatcher1_ProcessingFile(ByVal FileName As String)
    MsgBox "Watcher 1 fired: " & FileName
End Sub

Private Sub fDirWatcher2_ProcessingFile(ByVal FileName As String)
    MsgBox "watcher 2 fired: " & FileName
End Sub

Private Sub Form_Close()
    Set fDirWatcher1 = Nothing
    Set fDirWatcher2 = Nothing
End Sub

Private Sub Text0_AfterUpdate()
    Set fDirWatcher1 = New DropDirMonitor.DirWatcher
    fDirWatcher1.Init Text0.Value
End Sub

Private Sub Text2_AfterUpdate()
    Set fDirWatcher2 = New DropDirMonitor.DirWatcher
    fDirWatcher2.Init Text2.Value
End Sub

John W. Colby
Colby Consulting
www.ColbyConsulting.com

-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of JWColby
Sent: Saturday, April 21, 2007 3:38 PM
To: 'Access Developers discussion and problem solving'
Subject: Re: [AccessD] Cool stuff - was RE: using a dtsx in .Net

Thanks for that.  I just checked out this solution and while it does
function, it appears to have some serious limitations, specifically that it
can only monitor one directory, and apparently that it can pretty much do
nothing else.  The reason is that VBA is single threaded, and this code is a
tight loop with a DoEvents to allow the appearance of normalcy.  However it
really doesn't allow anything else to function.  I tried to make this a
class so that I could then do two (or more) instances.  The first instance
starts up but the second instance is not allowed to instantiate, with a "the
macro or validation rule prevents..." error thrown in the event of the text
box that tries to set up the second instance.  In essence it appears that
this would work just fine in limited situations where you just want an
application to monitor a directory, do something specific, then go right
back to the monitor loop, however it may completely prevent a broader
application from functioning after the loop is started.

One of the things I am trying to do is to start slowly doing some VB.Net
development.  I have a handful of things that really don't "fit" Access as a
development tool, e.g. running things as services.  I am also doing a lot
more stuff directly out in SQL Server 2005, and I want the ability to run a
powerful programming language that more directly talks to SQL Server, and
also does not require a copy of Access installed in order to operate.
VB.Net will give me that if I can ever get it figured out (I just need the
TIME!).  

The .Net code basically listens for EVENTS from a DotNet DiskWatcher object.
I haven't gotten so far as to determine whether when wrapped as a COM object
it can be used more than once from inside of Access.  The Web Seminar left
out the critical (written) instructions for compiling and registering the
com object, though the instructions are in the video, so I am headed back to
watch that portion of the video again.

John W. Colby
Colby Consulting
www.ColbyConsulting.com