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CBFS SImulate Download

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Components for BizTalk® and SQL Server® Integration Services that let you securely store and transfer information in your business automation solutions.
#6142
Posted: 05/06/2008 11:01:50
by adam  (Basic support level)
Joined: 03/13/2008
Posts: 18

I am evaluating CBFS for remote file download. I wanted to know how the OS would function if read and write operations were slowed down.

i simulated the download by pausing the thread for a period of time it would take to download the requested bytes at a connection speed.

In the mapper example c#

Code
onReadFile()
......

MAX_KBPS = 256;

float secondsToRead = ((float)BytesToRead / (float)MAX_KBPS);
int millisecondsToRead = (int)(1000 * secondsToRead);

Thread.Sleep(millisecondsToRead);


The following code works fine and i think does a good simulation to see if the OS can handle pauses during reads due to the slow access to data via the internet.

When i access the Virtual drive via Explorer and open an image file XP will load the default image viewer application and this will block all other calls to CBFS while the thread is sleeping. For example i open a 10 MB image file it take a few minutes to download (simulated via thread.sleep) during this time explorer will stop responding . But if i open any other type of file that also takes some time to download (simulated) explorer still functions as normal while the download is being simulated (CBFS does not block for other file events).

Why would CBFS cause explorer to hang when the default image viewer loads an image via a CBFS virtual drive? Is this because Explorer does not open the image viewer application in another thread and thus waits for the image application to display the image before returning back from the function call ?

#6162
Posted: 05/07/2008 07:50:58
by Eugene Mayevski (EldoS Corp.)

Quote
adam wrote:
Why would CBFS cause explorer to hang when the default image viewer loads an image via a CBFS virtual drive? Is this because Explorer does not open the image viewer application in another thread and thus waits for the image application to display the image before returning back from the function call ?


Yes, most likely the way the viewer is started causes Explorer to wait.
Microsoft products behave differently when the drive is remote rather than local. In this case they are more tolerant to delays. With CBFS 2.0 you will be able to map the drive as a network disk and this should solve most "waiting" problems.


Sincerely yours
Eugene Mayevski

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