[dba-VB] VB.Net "proxy" progress indicator

John,

I'm not sure I followed all of that, but you might be able to simplify
your life with a "ProxyHelper" class and separate classes for import and
export.  We tend to use objects like that to handle repetitive code for
performing similar actions.  We simply pass the appropriate objects into
the helper class, which handles all the UI stuff like progress meters,
message boxes, etc.  For example, we have a TransferHelper class which
calls into TranferImport, TransferExport, TransferByEmail, etc.    We
declare an instance of that class in the helper and use a structure to
retrieve the results from the specific class, and we use those results
to log the event, notify the user, etc.

Charlotte Foust

-----Original Message-----
From: dba-vb-bounces at databaseadvisors.com
[mailto:dba-vb-bounces at databaseadvisors.com] On Behalf Of jwcolby
Sent: Wednesday, December 26, 2007 8:05 AM
To: dba-vb at databaseadvisors.com
Subject: [dba-VB] VB.Net "proxy" progress indicator

I am trying to figure out how to do something that is probably simple if
I knew what I was doing.

I have a bunch of processes that do similar things.  They need to
visually report the same data.  For example I import CSV or flat files
from a directory of files.  Thus I need to report:

1) The directory being processed
2) The current file name
3) File N of M being processed
4) A "progress bar" showing that something is happening in the current
file
5) The NAME of the process currently running

I also EXPORT CSV files from a table out to a directory.  I need to
report:

1) The directory being exported to
2) The current file name
3) File N of M being exported
4) A "progress bar" showing that something is happening in the current
file
5) The NAME of the process currently running

As you can see, though the direction is different, and the class that
performs the process is different, they both need to report the same
kind of things.

So what I want to do is create a progress form that has controls and
labels for the controls to display this information.  I would like to
make the form not required for the process itself to run, i.e. I can
display the progress if I so desire or not show the progress.  All
progress is also being logged to tables and text files thus the display
is a "nice to have" feature.  

My concept of how to do that is with events, i.e. the class that
performs the process raises a series of events, and if there is a
listener, then the listener displays the information.  For example The
process raises a "Process Name" event and passes out the name of the
process it is running.
It then determines how many files will be required and raises a "Total
Files" event passing out the N (number of files) value.  It has a
counter by which it tracks which file it is currently processing and
raises an M (current file number) event every time it starts a file.  It
raises a "Current File name" event as it generates the file name it is
about to process.  And so forth.

Then a "proxy" progress indicator form can be opened.  This is where my
knowledge breaks down.  Somehow I have to pass in a "something" that can
have its events processed.  The problem is that the "something" changes.
One time it is a CSVExport class, the next it is a CSVImport class, the
next time it is a FlatFileExport class, the next it is a FlatFileImport
class.

Now given my weak knowledge of VB.Net, my first thought is to create a
"clsProxySource" as a base class.  This class has properties for holding
these pieces of data (process name, M, N, FileName etc) and methods
which raise events and pass out these variables.  I then inherit this
clsProxySource" in each of my process classes so that each of those
process classes has the properties and the ability to raise this event.

Next in the proxy display form I dimension a variable mclsProxySource of
type clsProxySource.  I define the event sinks for the events that the
clsProxySource sources.  In the New() I pass in the process class
instance that needs to display a status.  In the new it is coerced back
into a clsProxySource and stored in the mclsProxySource.

Now the process class can raise events and the form (if it exists) sinks
those events and displays the values in the controls on the form.

So... Is that how it is done, and if not how do I go about doing this?
If it is how it is done, the one piece I know for sure that I am missing
id the syntax for coercing the process class back into the
clsProxySource.  

If anyone could help me with this stuff I would be most appreciative.

Thanks,

John W. Colby
Colby Consulting
www.ColbyConsulting.com 

_______________________________________________
dba-VB mailing list
dba-VB at databaseadvisors.com
http://databaseadvisors.com/mailman/listinfo/dba-vb
http://www.databaseadvisors.com