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File Processor

, 8 Jan 2004
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An article on processing a File using the FileSystemWatcher class

Introduction

The purpose of this article is to address the lack of information that is available from the FileSystemWatcher utility class.

Background

The problem with the FileSystemWatcher class is we don't know when exactly has the file copy completed in order to process the file?

Using the code

The Monitor class wraps the FileSystemWatcher's functionality. The FileObject class encapsulates a newly copied file's general information as well as providing a method call that returns an output stream which can be manipulated.

// Monitor Class
// This is the implementation of a FileSystemWatcher class.
// The static ConfigurationInfo class is a technique I use to 
// make global information available to an application.
// The Notifyfilters are important so that the required IO event is fired.
//
private void SystemWatch()
{        
    FileSystemWatcher watcher = new FileSystemWatcher();
    watcher.Path = ConfigurationInfo.ModulePath+
       ConfigurationInfo.MonitorPath;
    watcher.NotifyFilter = NotifyFilters.LastWrite  | 
       NotifyFilters.FileName ; 
    watcher.Filter = "*.*";
    watcher.Created += new FileSystemEventHandler(OnChanged);
    watcher.Changed += new FileSystemEventHandler(OnChanged);
    watcher.EnableRaisingEvents = true;
    while(!bStop)
    {
        oEvent.WaitOne(); 
    }
}

The next tricky bit is knowing when to start processing the file i.e. when has the file copy completed.

Someone else might come up with a better solution but in the RAD environment that I program in development speed and stability are very important. The trick is to user a SystemTimer which has a fairly low resource impact and increment the timer interval every time an IO event is fired. Obviously once the file copy has completed the interval will not be incremented and the timer will timeout.

//
// The FileObject when constructed creates and starts the LogTimer class.
// LogTimer wraps a System timer.
//
private System.Timers.Timer LogTimer = new System.Timers.Timer();
.
.
//
// LogTimer constructor. The AutoReset set to false 
// means that the timer will only fire once.
//
public LogFileTimer(int tTime, string Name)
{
    PollTime = tTime;
    fileName = Name;
    LogTimer.Elapsed += new ElapsedEventHandler(Timeup);
    LogTimer.Interval = PollTime;
    LogTimer.Enabled = true;
    LogTimer.AutoReset = false; 
} 

Points of Interest

The big problem this solution solves is that large files copied into a monitored directory can only be processed once the copy or FTP has completed. I think the solution is neat but probably can be scaled down even further. I used these objects to convert a very large FTP'd flat file into XML.

Conclusion

This is my first article so go easy.

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

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About the Author

RichardRoe
Web Developer
South Africa South Africa
I studied IT in 1987 and have been working ever since in on projects that range from coding animation in pascal and assembler to writing secure internet banking web sites.
 
I live in South Africa and I think because of it's size we're required to do more for less which makes highly skilled in a wide range of skills and technologies.
 
I have the bonus of living in a coastal town so time away from computers is spent around the sea and in sunshine and nature.

Comments and Discussions

 
GeneralSemaphore File Pinmembercosmicb6-Sep-07 14:42 
QuestionLower Case Full Path and Name PinmemberNizhum27-May-07 2:40 
QuestionCan you please tell how to test this program? PinmemberBharat Gadhia11-Aug-06 12:37 
AnswerRe: Can you please tell how to test this program? Pinmembercosmicb6-Sep-07 14:36 
QuestionCan you please tell how to test this program? PinmemberBharat Gadhia11-Aug-06 12:36 
Can you please throw light as to how this proram works or how to test it? It is not clear what one should do when program stops at console.read() line. I have created a file watcher application, where I want to move the created file to another folder after it is obtained from ftp site.
 
Thank you.
 
In life, failures teach you as much as — or perhaps more than — successes.
Thank you very much for the help.

GeneralCorrect Method For New Files Pinmemberrohdek22-Jul-06 15:56 
GeneralAnother approach without using timer or exception PinmemberChitrsen18-Jul-06 1:52 
QuestionRe: Another approach without using timer or exception Pinmembersides_dale14-Apr-07 16:48 
AnswerRe: Another approach without using timer or exception Pinmemberkrishpuma25-May-07 1:00 
QuestionHow to implement via windows services Pinmembervittoriod18-Oct-05 5:14 
GeneralBetter lightweight approach with FileShare exclusive open PinmemberPras Biswas10-Aug-05 5:34 
GeneralRe: Better lightweight approach with FileShare exclusive open Pinmemberrickyroe29-Jan-06 23:44 
GeneralWorks Great PinmemberNikhils3316-May-05 5:44 
GeneralProgram bombs for large files PinmemberSimeon_Shapiro7-May-05 23:44 
GeneralRe: Program bombs for large files Pinmembersdelbos30-May-05 6:01 
GeneralRe: Program bombs for large files Pinmemberrickyroe29-Jan-06 23:46 
GeneralRe: Program bombs for large files Pinmemberrickyroe29-Jan-06 23:49 
GeneralRe: Program bombs for large files PinmemberThe Prisoner18-Sep-06 1:21 
Generalremove when event fires PinmemberTyler Jensen12-Apr-05 6:26 
GeneralRe: remove when event fires Pinmembercosmicb14-Apr-05 1:00 
GeneralWhy both onChanged and onCreated Pinmemberjabailo21-Mar-05 8:08 
GeneralRe: Why both onChanged and onCreated Pinmembercosmicb14-Apr-05 0:55 
Generaldoesn`t detect Copy Pinmemberkadnan27-Oct-04 22:36 
GeneralC#.net (saving a file ) PinsussAnonymous12-May-04 6:42 
GeneralHere's a solution... PinsussDamir Cuca23-Mar-04 15:41 

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