[dba-VB] Background worker threads

Bueno, thanks!

John W. Colby
www.ColbyConsulting.com


Charlotte Foust wrote:
> I'm sorry, John, I missed the contextt of your question.   We don't use
> background workers that way, so I don't have an answer for you.
> 
> Charlotte 
> 
> -----Original Message-----
> From: dba-vb-bounces at databaseadvisors.com
> [mailto:dba-vb-bounces at databaseadvisors.com] On Behalf Of jwcolby
> Sent: Wednesday, April 30, 2008 9:05 AM
> To: Discussion concerning Visual Basic and related programming issues.
> Subject: Re: [dba-VB] Background worker threads
> 
> Charlotte,
> 
> Could you be a little more verbose?
> 
> I have spent about 6 hours now Googling and reading EXACTLY the same
> (though written by different authors) code "the button starts the
> thread, the thread increments the number, the thread raises its event
> and passes a "percent done" to the form where it is used to update a
> progress bar".
> 
> Give me a break!
> 
> To be honest I am astonished that FORTY different people thought that it
> was necessary to publish identical content articles.  None of which
> answers either of my questions.
> 
> I have a class.
> 
> The class has TWO BackgroundWorker objects defined Withevents.
> 
> bgwParseData is running a function that creates a class to load data
> from a SQL server, and once loaded, parse that data.  The basic code WAS
> working before I carved it out into a worker.
> 
> bgwUpdateData is running a method of a class that updates data back to
> SQL Server.  The basic code WAS working before I carved it out into a
> worker.
> 
> So... a single data class, two methods, one reads / parses the data in
> an ADO DataTable, the second writes the datatable back to SQL Server.
> 
> Two threads, bgwParseData generates the data class and calls the
> read/Parse method, then stores the class in a collection.  bgwUpdateData
> watches the collection, pulls the class out and calls the update method.
> 
> Or that is the theory.  I have asked whether it is legal for one
> background worker to write to a collection while a second background
> worker reads that collection.  No answer so far.
> 
> The second issue is how can bgwParseData update THREE different text
> boxes on the main form.  All of the examples show a cute "progress bar".
> 
>   I don't want a progress bar, I want THREE text boxes to display data
> from the process running in the background worker.
> 
> I know that I can create events and raise them, and I DID THAT before I
> started converting to backgroundworkers.  That was easy.  HOWEVER the
> way I read it I can't raise those same events from the BackgroundWorker
> thread because the event sink updates a physical control on the form,
> and that is a no-no from a thread.
> 
> Unfortunately, as always happens with the books, they don't discuss
> anything more complicated than incrementing a number and passing that
> number back to a progress bar on the form.  I have seen that (almost)
> identical code in probably FORTY different articles on using the
> backgroundworker.  All saying EXACTLY the same, useless (to me) thing.
> 
> Sigh.
> 
> John W. Colby
> www.ColbyConsulting.com
> 
> 
> Charlotte Foust wrote:
>> You can create your own events with whatever parameters you want and 
>> raise those.  Just Dim Public Event Whatever(parameter)  Then raise it
> 
>> as needed.
>>
>> Charlotte Foust
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